Using Gitea-compatible upload-artifact action

Also improved error reporting for common failure cases.

.github/workflows/main.yml

@@ -16,11 +16,16 @@ jobs:
     env:
       ADDON_NAME: io_scene_psk_psa
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
-          lfs: true
+          persist-credentials: true
       - name: Checkout LFS objects
-        run: git lfs checkout
+        run: |
+          git lfs install --local
+          AUTH=$(git config --local http.${{ github.server_url }}/.extraheader)
+          git config --local --unset http.${{ github.server_url }}/.extraheader
+          git config --local http.${{ github.server_url }}/${{ github.repository }}.git/info/lfs/objects/batch.extraheader "$AUTH"
+          git lfs pull
       - uses: SebRollen/toml-action@v1.2.0
         id: read_manifest
         with:
@@ -38,8 +43,7 @@ jobs:
           sudo apt-get install python3 -y
       - name: Install Requirements
         run: |
-          python3 -m pip install --upgrade pip
-          python3 -m pip install virtualenv
+          sudo apt-get install python3-virtualenv -y
           python3 -m virtualenv venv
           source venv/bin/activate
           pip install pytest-blender
@@ -69,7 +73,7 @@ jobs:
           source venv/bin/activate
           pytest -svv tests --blender-addons-dirs .
       - name: Archive addon
-        uses: actions/upload-artifact@v4
+        uses: https://github.com/christopherHX/gitea-upload-artifact@v4
         with:
           name: ${{ env.ADDON_NAME }}-${{ github.ref_name }}-${{ github.sha }}
           path: |

Dockerfile

@@ -20,9 +20,10 @@ RUN BLENDER_EXECUTABLE=$(blender-downloader $BLENDER_VERSION --extract --remove-
 RUN pip install pytest-cov
 
 # Source the environment variables and install Python dependencies
+# TODO: would be nice to have these installed in the bash script below.
 RUN . /etc/environment && \
     $BLENDER_PYTHON -m ensurepip && \
-    $BLENDER_PYTHON -m pip install pytest pytest-cov psk-psa-py
+    $BLENDER_PYTHON -m pip install pytest pytest-cov psk-psa-py==0.0.4
 
 # Persist BLENDER_EXECUTABLE as an environment variable
 RUN echo $(cat /blender_executable_path) > /tmp/blender_executable_path_env && \

README.md

@@ -13,37 +13,43 @@ For Blender 4.2 and higher, download the latest version from the [Blender Extens
 For Blender 4.1 and lower, see [Legacy Compatibility](#legacy-compatibility).
 
 # Features
-* Full PSK/PSA import and export capabilities.
-* Non-standard file section data (.pskx) is supported for import only (vertex normals, extra UV channels, vertex colors, shape keys).
+* [Bone collections](https://docs.blender.org/manual/en/latest/animation/armatures/bones/bone_collections.html#bone-collections) can be excluded from PSK/PSA export (useful for excluding non-contributing bones such as IK controllers).
+* [Collection Exporters](https://docs.blender.org/manual/en/latest/scene_layout/collections/collections.html#exporters) for reliable, repeatable export workflow.
+* Non-standard model data (.pskx) is supported for import only (vertex normals, extra UV channels, vertex colors, shape keys).
+* Manual re-ordering of material slots on export.
+* Non-standard animation data is supported for import only (scale keys).
 * Fine-grained PSA sequence importing for efficient workflow when working with large PSA files.
 * PSA sequence metadata (e.g., frame rate) is preserved on import, allowing this data to be reused on export.
-* [Bone collections](https://docs.blender.org/manual/en/latest/animation/armatures/bones/bone_collections.html#bone-collections) can be excluded from PSK/PSA export (useful for excluding non-contributing bones such as IK controllers).
 * PSA sequences can be exported directly from actions or delineated using a scene's [timeline markers](https://docs.blender.org/manual/en/latest/animation/markers.html), pose markers, or NLA track strips, allowing direct use of the [NLA](https://docs.blender.org/manual/en/latest/editors/nla/index.html) when creating sequences.
-* Manual re-ordering of material slots.
-* Multiple armature objects can be exported to a single PSK or PSA file, allowing seamless use of [action slots](https://docs.blender.org/manual/en/latest/animation/actions.html#action-slots).
-* Support for exporting instance collections.
+* Compress exported sequences via resampling ratios or frame quotas.
 
 # Usage
-## Exporting a PSK
-1. Select the mesh objects you wish to export.
-2. Navigate to `File` > `Export` > `Unreal PSK (.psk)`.
-3. Enter the file name and click `Export`.
 
-## Importing a PSK/PSKX
+## Import
+
+### Importing a PSK/PSKX
 1. Navigate to `File` > `Import` > `Unreal PSK (.psk/.pskx)`.
 2. Select the PSK file you want to import and click `Import`.
 
-## Exporting a PSA
-1. Select the armature objects you wish to export.
-2. Navigate to `File` > `Export` > `Unreal PSA (.psa)`.
-3. Enter the file name and click `Export`.
-
-## Importing a PSA
+### Importing a PSA
 1. Select an armature that you want import animations for.
 2. Navigate to `File` > `Import` > `Unreal PSA (.psa)`.
 3. Select the PSA file you want to import.
 4. Select the sequences that you want to import and click `Import`.
 
+## Export
+It is highly recommended to use the provided [Collection Exporters](https://docs.blender.org/manual/en/latest/scene_layout/collections/collections.html#exporters) workflow, since it allows for highly reliable, repeatable exports of both PSK and PSA files. However, the traditional export workflow is available as well.
+
+### Exporting a PSK
+1. Select the mesh objects you wish to export.
+2. Navigate to `File` > `Export` > `Unreal PSK (.psk)`.
+3. Enter the file name and click `Export`.
+
+### Exporting a PSA
+1. Select the armature objects you wish to export.
+2. Navigate to `File` > `Export` > `Unreal PSA (.psa)`.
+3. Enter the file name and click `Export`.
+
 > Note that in order to see the imported actions applied to your armature, you must use the [Dope Sheet](https://docs.blender.org/manual/en/latest/editors/dope_sheet/introduction.html) or [Nonlinear Animation](https://docs.blender.org/manual/en/latest/editors/nla/introduction.html) editors.
 
 # FAQ

io_scene_psk_psa/__init__.py

@@ -1,32 +1,40 @@
-from bpy.app.handlers import persistent
-
-from .shared import types as shared_types, helpers as shared_helpers
-from .shared import dfs as shared_dfs, ui as shared_ui
+from .shared import (
+    types as shared_types,
+    helpers as shared_helpers,
+    dfs as shared_dfs,
+    ui as shared_ui,
+    operators as shared_operators,
+)
 from .psk import (
     builder as psk_builder,
     importer as psk_importer,
     properties as psk_properties,
+    ui as psk_ui,
 ) 
-from .psk import ui as psk_ui
 from .psk.export import (
     operators as psk_export_operators,
     properties as psk_export_properties,
     ui as psk_export_ui,
 )
-from .psk.import_ import operators as psk_import_operators
-
+from .psk.import_ import (
+    operators as psk_import_operators,
+)
 from .psa import (
     config as psa_config,
     builder as psa_builder,
     importer as psa_importer,
+    file_handlers as psa_file_handlers,
 )
 from .psa.export import (
     properties as psa_export_properties,
     ui as psa_export_ui,
     operators as psa_export_operators,
 )
-from .psa.import_ import operators as psa_import_operators
-from .psa.import_ import ui as psa_import_ui, properties as psa_import_properties
+from .psa.import_ import (
+    operators as psa_import_operators,
+    ui as psa_import_ui,
+    properties as psa_import_properties,
+)
 
 _needs_reload = 'bpy' in locals()
 
@@ -37,6 +45,7 @@ if _needs_reload:
     importlib.reload(shared_types)
     importlib.reload(shared_dfs)
     importlib.reload(shared_ui)
+    importlib.reload(shared_operators)
 
     importlib.reload(psk_builder)
     importlib.reload(psk_importer)
@@ -56,6 +65,7 @@ if _needs_reload:
     importlib.reload(psa_import_properties)
     importlib.reload(psa_import_operators)
     importlib.reload(psa_import_ui)
+    importlib.reload(psa_file_handlers)
 
 import bpy
 from bpy.props import PointerProperty
@@ -80,6 +90,7 @@ def psa_import_menu_func(self, context):
 _modules = (
     shared_types,
     shared_ui,
+    shared_operators,
     psk_properties,
     psk_ui,
     psk_import_operators,
@@ -91,7 +102,8 @@ _modules = (
     psa_export_ui,
     psa_import_properties,
     psa_import_operators,
-    psa_import_ui
+    psa_import_ui,
+    psa_file_handlers,
 )
 
 def register():
@@ -101,21 +113,21 @@ def register():
     bpy.types.TOPBAR_MT_file_import.append(psk_import_menu_func)
     bpy.types.TOPBAR_MT_file_export.append(psa_export_menu_func)
     bpy.types.TOPBAR_MT_file_import.append(psa_import_menu_func)
-    bpy.types.Material.psk = PointerProperty(type=psk_properties.PSX_PG_material, options={'HIDDEN'})
-    bpy.types.Scene.psx_export = PointerProperty(type=shared_types.PSX_PG_scene_export, options={'HIDDEN'})
-    bpy.types.Scene.psa_import = PointerProperty(type=psa_import_properties.PSA_PG_import, options={'HIDDEN'})
-    bpy.types.Scene.psa_export = PointerProperty(type=psa_export_properties.PSA_PG_export, options={'HIDDEN'})
-    bpy.types.Scene.psk_export = PointerProperty(type=psk_export_properties.PSK_PG_export, options={'HIDDEN'})
-    bpy.types.Action.psa_export = PointerProperty(type=shared_types.PSX_PG_action_export, options={'HIDDEN'})
+    setattr(bpy.types.Material, 'psk', PointerProperty(type=psk_properties.PSX_PG_material, options={'HIDDEN'}))
+    setattr(bpy.types.Scene, 'psx_export', PointerProperty(type=shared_types.PSX_PG_scene_export, options={'HIDDEN'}))
+    setattr(bpy.types.Scene, 'psa_import', PointerProperty(type=psa_import_properties.PSA_PG_import, options={'HIDDEN'}))
+    setattr(bpy.types.Scene, 'psa_export', PointerProperty(type=psa_export_properties.PSA_PG_export, options={'HIDDEN'}))
+    setattr(bpy.types.Scene, 'psk_export', PointerProperty(type=psk_export_properties.PSK_PG_export, options={'HIDDEN'}))
+    setattr(bpy.types.Action, 'psa_export', PointerProperty(type=shared_types.PSX_PG_action_export, options={'HIDDEN'}))
 
 
 def unregister():
-    del bpy.types.Material.psk
-    del bpy.types.Scene.psx_export
-    del bpy.types.Scene.psa_import
-    del bpy.types.Scene.psa_export
-    del bpy.types.Scene.psk_export
-    del bpy.types.Action.psa_export
+    delattr(bpy.types.Material, 'psk')
+    delattr(bpy.types.Scene, 'psx_export')
+    delattr(bpy.types.Scene, 'psa_import')
+    delattr(bpy.types.Scene, 'psa_export')
+    delattr(bpy.types.Scene, 'psk_export')
+    delattr(bpy.types.Action, 'psa_export')
     bpy.types.TOPBAR_MT_file_export.remove(psk_export_menu_func)
     bpy.types.TOPBAR_MT_file_import.remove(psk_import_menu_func)
     bpy.types.TOPBAR_MT_file_export.remove(psa_export_menu_func)
@@ -126,16 +138,3 @@ def unregister():
 
 if __name__ == '__main__':
     register()
-
-
-@persistent
-def load_handler(dummy):
-    # Convert old `psa_sequence_fps` property to new `psa_export.fps` property.
-    # This is only needed for backwards compatibility with files that may have used older versions of the addon.
-    for action in bpy.data.actions:
-        if 'psa_sequence_fps' in action:
-            action.psa_export.fps = action['psa_sequence_fps']
-            del action['psa_sequence_fps']
-
-
-bpy.app.handlers.load_post.append(load_handler)

io_scene_psk_psa/blender_manifest.toml

@@ -1,6 +1,6 @@
 schema_version = "1.0.0"
 id = "io_scene_psk_psa"
-version = "9.0.2"
+version = "9.1.1"
 name = "Unreal PSK/PSA (.psk/.psa)"
 tagline = "Import and export PSK and PSA files used in Unreal Engine"
 maintainer = "Colin Basnett <cmbasnett@gmail.com>"
@@ -14,7 +14,7 @@ license = [
   "SPDX:GPL-3.0-or-later",
 ]
 wheels = [
-  './wheels/psk_psa_py-0.0.1-py3-none-any.whl'
+  './wheels/psk_psa_py-0.0.4-py3-none-any.whl'
 ]
 
 [build]

io_scene_psk_psa/psa/builder.py

@@ -1,16 +1,16 @@
 from bpy.types import Action, AnimData, Context, Object, PoseBone
 
 from psk_psa_py.psa.data import Psa
-from typing import Dict, List, Optional, Tuple
+from typing import Tuple
 from mathutils import Matrix, Quaternion, Vector
 
-from ..shared.helpers import PsxBoneCollection, create_psx_bones, get_coordinate_system_transform
+from ..shared.helpers import PsxBoneCollection, convert_bpy_quaternion_to_psx_quaternion, convert_vector_to_vector3, create_psx_bones, get_coordinate_system_transform
 
 
 class PsaBuildSequence:
     class NlaState:
         def __init__(self):
-            self.action: Optional[Action] = None
+            self.action: Action | None = None
             self.frame_start: int = 0
             self.frame_end: int = 0
 
@@ -22,16 +22,16 @@ class PsaBuildSequence:
         self.compression_ratio: float = 1.0
         self.key_quota: int = 0
         self.fps: float = 30.0
-        self.group: Optional[str] = None
+        self.group: str | None = None
 
 
 class PsaBuildOptions:
     def __init__(self):
-        self.armature_objects: List[Object] = []
-        self.animation_data: Optional[AnimData] = None
-        self.sequences: List[PsaBuildSequence] = []
+        self.armature_objects: list[Object] = []
+        self.animation_data: AnimData | None = None
+        self.sequences: list[PsaBuildSequence] = []
         self.bone_filter_mode: str = 'ALL'
-        self.bone_collection_indices: List[PsxBoneCollection] = []
+        self.bone_collection_indices: list[PsxBoneCollection] = []
         self.sequence_name_prefix: str = ''
         self.sequence_name_suffix: str = ''
         self.scale = 1.0
@@ -39,7 +39,6 @@ class PsaBuildOptions:
         self.export_space = 'WORLD'
         self.forward_axis = 'X'
         self.up_axis = 'Z'
-        self.root_bone_name = 'ROOT'
         self.sequence_source = 'ACTIONS'  # One of ('ACTIONS', 'TIMELINE_MARKERS', 'NLA_STRIPS')
     
     @property
@@ -47,30 +46,79 @@ class PsaBuildOptions:
         return 'DATA' if self.sequence_source == 'ACTIVE_ACTION' else 'OBJECT'
 
 
+class PsaExportBone:
+    def __init__(self,
+                    pose_bone: PoseBone | None,
+                    armature_object: Object | None,
+                    scale: Vector):
+        self.pose_bone = pose_bone
+        self.armature_object = armature_object
+        self.scale = scale
+    
+    @property
+    def is_armature_root_bone(self) -> bool:
+        return self.pose_bone is not None and self.pose_bone.parent is None
+    
+    @property
+    def is_attached_to_armature(self) -> bool:
+        return self.get_attached_armature() is not None
+    
+    def get_attached_armature(self) -> tuple[Object, PoseBone] | None:
+        if not self.is_armature_root_bone:
+            return None
+        assert self.armature_object is not None
+        match self.armature_object.parent_type:
+            case 'BONE':
+                parent_bone_name = self.armature_object.parent_bone
+                assert self.armature_object.parent is not None
+                parent_armature_object = self.armature_object.parent
+                assert parent_armature_object.pose is not None
+                parent_pose_bone = parent_armature_object.pose.bones.get(parent_bone_name)
+                if parent_pose_bone is None:
+                    return None
+                return (parent_armature_object, parent_pose_bone)
+            case _:
+                return None
+    
+    def get_attached_armature_transform(self) -> Matrix:
+        attached_armature, attached_pose_bone = self.get_attached_armature() or (None, None)
+        if attached_armature is None or attached_pose_bone is None:
+            return Matrix.Identity(4)
+        if attached_pose_bone.parent is not None:
+            attached_bone_matrix = attached_pose_bone.parent.matrix.inverted() @ attached_pose_bone.matrix
+        else:
+            attached_bone_matrix = attached_armature.matrix_world @ attached_pose_bone.matrix
+        return attached_bone_matrix
+
 def _get_pose_bone_location_and_rotation(
-        pose_bone: Optional[PoseBone],
-        armature_object: Optional[Object],
+    pose_bone: PoseBone,
+    armature_object: Object,
+    export_bone: PsaExportBone,
     export_space: str,
     scale: Vector,
     coordinate_system_transform: Matrix,
-        has_false_root_bone: bool,
 ) -> Tuple[Vector, Quaternion]:
-    is_false_root_bone = pose_bone is None and armature_object is None
-
-    if is_false_root_bone:
-        pose_bone_matrix = coordinate_system_transform
-    elif pose_bone is not None and pose_bone.parent is not None:
-        pose_bone_matrix = pose_bone.matrix
-        pose_bone_parent_matrix = pose_bone.parent.matrix
-        pose_bone_matrix = pose_bone_parent_matrix.inverted() @ pose_bone_matrix
+    if pose_bone.parent is not None:
+        pose_bone_matrix = pose_bone.parent.matrix.inverted() @ pose_bone.matrix
     else:
         # Root bone
-        if has_false_root_bone:
-            pose_bone_matrix = armature_object.matrix_world @ pose_bone.matrix
-        else:
         # Get the bone's pose matrix and transform it into the export space.
         # In the case of an 'ARMATURE' export space, this will be the inverse of armature object's world matrix.
         # Otherwise, it will be the identity matrix.
+
+        if export_bone.is_attached_to_armature:
+            # Get the world space matrix of both this bone and the bone that we're attached to,
+            # then calculate a matrix relative to the attached bone.
+            world_matrix = armature_object.matrix_world @ pose_bone.matrix
+            assert export_bone.armature_object
+            my_parent = export_bone.armature_object.parent
+            assert my_parent
+            my_parent_bone = export_bone.armature_object.parent_bone
+            assert my_parent.pose
+            parent_pose_bone = my_parent.pose.bones[my_parent_bone]
+            parent_world_matrix = my_parent.matrix_world @ parent_pose_bone.matrix
+            pose_bone_matrix = parent_world_matrix.inverted() @ world_matrix
+        else:
             match export_space:
                 case 'ARMATURE':
                     pose_bone_matrix = pose_bone.matrix
@@ -80,7 +128,6 @@ def _get_pose_bone_location_and_rotation(
                     pose_bone_matrix = Matrix.Identity(4)
                 case _:
                     assert False, f'Invalid export space: {export_space}'
-
             # The root bone is the only bone that should be transformed by the coordinate system transform, since all
             # other bones are relative to their parent bones.
             pose_bone_matrix = coordinate_system_transform @ pose_bone_matrix
@@ -88,16 +135,10 @@ def _get_pose_bone_location_and_rotation(
     location = pose_bone_matrix.to_translation()
     rotation = pose_bone_matrix.to_quaternion().normalized()
 
+    if pose_bone.parent is not None:
         # Don't apply scale to the root bone of armatures if we have a false root.
-    if not has_false_root_bone or (pose_bone is None or pose_bone.parent is not None):
+        # TODO: probably remove this?
         location *= scale
-
-    if has_false_root_bone:
-        is_child_bone = not is_false_root_bone
-    else:
-        is_child_bone = pose_bone.parent is not None
-
-    if is_child_bone:
         rotation.conjugate()
 
     return location, rotation
@@ -120,7 +161,6 @@ def build_psa(context: Context, options: PsaBuildOptions) -> Psa:
     psx_bone_create_result = create_psx_bones(
         armature_objects=armature_objects_for_bones,
         export_space=options.export_space,
-        root_bone_name=options.root_bone_name,
         forward_axis=options.forward_axis,
         up_axis=options.up_axis,
         scale=options.scale,
@@ -132,7 +172,7 @@ def build_psa(context: Context, options: PsaBuildOptions) -> Psa:
     # Build list of PSA bones.
     # Note that the PSA bones are just here to validate the hierarchy.
     # The bind pose information is not used by the engine.
-    psa.bones = [psx_bone for psx_bone, _ in psx_bone_create_result.bones]
+    psa.bones = [bone.psx_bone for bone in psx_bone_create_result.bones]
 
     # No bones are going to be exported.
     if len(psa.bones) == 0:
@@ -144,7 +184,7 @@ def build_psa(context: Context, options: PsaBuildOptions) -> Psa:
         export_sequence.name = export_sequence.name.strip()
 
     # Save each armature object's current action and frame so that we can restore the state once we are done.
-    saved_armature_object_actions = {o: o.animation_data.action for o in options.armature_objects}
+    saved_armature_object_actions = {o: (o.animation_data.action if o.animation_data else None) for o in options.armature_objects}
     saved_frame_current = context.scene.frame_current
 
     # Now build the PSA sequences.
@@ -197,29 +237,20 @@ def build_psa(context: Context, options: PsaBuildOptions) -> Psa:
 
         # Link the action to the animation data and update view layer.
         for armature_object in options.armature_objects:
+            if armature_object.animation_data:
                 armature_object.animation_data.action = export_sequence.nla_state.action
 
+        assert context.view_layer
         context.view_layer.update()
 
         def add_key(location: Vector, rotation: Quaternion):
             key = Psa.Key()
-            key.location.x = location.x
-            key.location.y = location.y
-            key.location.z = location.z
-            key.rotation.x = rotation.x
-            key.rotation.y = rotation.y
-            key.rotation.z = rotation.z
-            key.rotation.w = rotation.w
+            key.location = convert_vector_to_vector3(location)
+            key.rotation = convert_bpy_quaternion_to_psx_quaternion(rotation)
             key.time = 1.0 / psa_sequence.fps
             psa.keys.append(key)
 
-        class PsaExportBone:
-            def __init__(self, pose_bone: Optional[PoseBone], armature_object: Optional[Object], scale: Vector):
-                self.pose_bone = pose_bone
-                self.armature_object = armature_object
-                self.scale = scale
-
-        armature_scales: Dict[Object, Vector] = {}
+        armature_scales: dict[Object, Vector] = {}
 
         # Extract the scale from the world matrix of the evaluated armature object.
         for armature_object in options.armature_objects:
@@ -231,26 +262,27 @@ def build_psa(context: Context, options: PsaBuildOptions) -> Psa:
         # Create a list of export pose bones, in the same order as the bones as they appear in the armature.
         # The object contains the pose bone, the armature object, and a pre-calculated scaling value to apply to the
         # locations.
-        export_bones: List[PsaExportBone] = []
+        export_bones: list[PsaExportBone] = []
 
-        for psx_bone, armature_object in psx_bone_create_result.bones:
-            if armature_object is None:
-                export_bones.append(PsaExportBone(None, None, Vector((1.0, 1.0, 1.0))))
+        for bone in psx_bone_create_result.bones:
+            if bone.armature_object is None:
+                export_bone = PsaExportBone(None, None, Vector((1.0, 1.0, 1.0)))
+                export_bones.append(export_bone)
                 continue
 
-            assert armature_object.pose
-            pose_bone = armature_object.pose.bones[psx_bone.name.decode('windows-1252')]
+            assert bone.armature_object.pose
+            pose_bone = bone.armature_object.pose.bones[bone.psx_bone.name.decode('windows-1252')]
 
-            export_bones.append(PsaExportBone(pose_bone, armature_object, armature_scales[armature_object]))
+            export_bones.append(PsaExportBone(pose_bone, bone.armature_object, armature_scales[bone.armature_object]))
 
         match options.sampling_mode:
             case 'INTERPOLATED':
                 # Used as a store for the last frame's pose bone locations and rotations.
-                last_frame: Optional[int] = None
-                last_frame_bone_poses: List[Tuple[Vector, Quaternion]] = []
+                last_frame: int | None = None
+                last_frame_bone_poses: list[tuple[Vector, Quaternion]] = []
 
-                next_frame: Optional[int] = None
-                next_frame_bone_poses: List[Tuple[Vector, Quaternion]] = []
+                next_frame: int | None = None
+                next_frame_bone_poses: list[tuple[Vector, Quaternion]] = []
 
                 for _ in range(frame_count):
                     if last_frame is None or last_frame != int(frame):
@@ -269,10 +301,10 @@ def build_psa(context: Context, options: PsaBuildOptions) -> Psa:
                                 location, rotation = _get_pose_bone_location_and_rotation(
                                     export_bone.pose_bone,
                                     export_bone.armature_object,
+                                    export_bone,
                                     options.export_space,
                                     export_bone.scale,
-                                    coordinate_system_transform=coordinate_system_transform,
-                                    has_false_root_bone=psx_bone_create_result.has_false_root_bone,
+                                    coordinate_system_transform=coordinate_system_transform
                                 )
                                 last_frame_bone_poses.append((location, rotation))
 
@@ -292,10 +324,10 @@ def build_psa(context: Context, options: PsaBuildOptions) -> Psa:
                                 location, rotation = _get_pose_bone_location_and_rotation(
                                     pose_bone=export_bone.pose_bone,
                                     armature_object=export_bone.armature_object,
+                                    export_bone=export_bone,
                                     export_space=options.export_space,
                                     scale=export_bone.scale,
                                     coordinate_system_transform=coordinate_system_transform,
-                                    has_false_root_bone=psx_bone_create_result.has_false_root_bone,
                                 )
                                 next_frame_bone_poses.append((location, rotation))
 
@@ -319,10 +351,10 @@ def build_psa(context: Context, options: PsaBuildOptions) -> Psa:
                         location, rotation = _get_pose_bone_location_and_rotation(
                             pose_bone=export_bone.pose_bone,
                             armature_object=export_bone.armature_object,
+                            export_bone=export_bone,
                             export_space=options.export_space,
                             scale=export_bone.scale,
                             coordinate_system_transform=coordinate_system_transform,
-                            has_false_root_bone=psx_bone_create_result.has_false_root_bone,
                         )
                         add_key(location, rotation)
 

io_scene_psk_psa/psa/config.py

@@ -1,6 +1,5 @@
 import re
 from configparser import ConfigParser
-from typing import Dict, List
 
 REMOVE_TRACK_LOCATION = (1 << 0)
 REMOVE_TRACK_ROTATION = (1 << 1)
@@ -8,7 +7,7 @@ REMOVE_TRACK_ROTATION = (1 << 1)
 
 class PsaConfig:
     def __init__(self):
-        self.sequence_bone_flags: Dict[str, Dict[int, int]] = dict()
+        self.sequence_bone_flags: dict[str, dict[int, int]] = dict()
 
 
 def _load_config_file(file_path: str) -> ConfigParser:
@@ -48,7 +47,7 @@ def _get_bone_flags_from_value(value: str) -> int:
             return 0
 
 
-def read_psa_config(psa_sequence_names: List[str], file_path: str) -> PsaConfig:
+def read_psa_config(psa_sequence_names: list[str], file_path: str) -> PsaConfig:
     psa_config = PsaConfig()
 
     config = _load_config_file(file_path)

io_scene_psk_psa/psa/export/operators.py

@@ -1,23 +1,27 @@
+from abc import abstractmethod
 from collections import Counter
-from typing import List, Iterable, Dict, Tuple, cast as typing_cast
+from typing import Iterable, Sequence, Tuple, cast as typing_cast
 
 import bpy
 import re
 from bpy.props import StringProperty
-from bpy.types import Context, Action, Object, AnimData, TimelineMarker, Operator, Armature
+from bpy.types import Context, Action, Object, AnimData, TimelineMarker, Operator, Armature, UILayout, Scene, ActionKeyframeStrip
 from bpy_extras.io_utils import ExportHelper
 
 from .properties import (
     PSA_PG_export,
-    PSA_PG_export_action_list_item,
+    PsaExportMixin,
+    PsaExportSequenceMixin,
     filter_sequences,
     get_sequences_from_name_and_frame_range,
 )
 from .ui import PSA_UL_export_sequences
 from ..builder import build_psa, PsaBuildSequence, PsaBuildOptions
 from psk_psa_py.psa.writer import write_psa_to_file
-from ...shared.helpers import populate_bone_collection_list, get_nla_strips_in_frame_range, PsxBoneCollection
+from ...shared.helpers import get_collection_export_operator_from_context, get_collection_from_context, get_psk_input_objects_for_collection, populate_bone_collection_list, get_nla_strips_in_frame_range, PsxBoneCollection
+from ...shared.types import PSX_PG_action_export
 from ...shared.ui import draw_bone_filter_mode
+from ...shared.operators import PSK_OT_bone_collection_list_populate, PSK_OT_bone_collection_list_select_all
 
 
 def get_sequences_propnames_from_source(sequence_source: str) -> Tuple[str, str]:
@@ -47,6 +51,8 @@ def is_action_for_object(obj: Object, action: Action):
     # The nesting here is absolutely bonkers.
     for layer in action.layers:
         for strip in layer.strips:
+            if not isinstance(strip, ActionKeyframeStrip):
+                continue
             for channelbag in strip.channelbags:
                 for fcurve in channelbag.fcurves:
                     match = re.match(r'pose\.bones\[\"([^\"]+)\"](\[\"([^\"]+)\"])?', fcurve.data_path)
@@ -59,18 +65,23 @@ def is_action_for_object(obj: Object, action: Action):
     return False
 
 
-def update_actions_and_timeline_markers(context: Context, armature_objects: Iterable[Object]):
-    pg = getattr(context.scene, 'psa_export')
+def update_actions_and_timeline_markers(context: Context, armature_objects: Sequence[Object], pg: PsaExportMixin):
+    assert context.scene is not None
 
     # Clear actions and markers.
     pg.action_list.clear()
     pg.marker_list.clear()
     pg.active_action_list.clear()
 
-    # Get animation data.
-    # TODO: Not sure how to handle this with multiple armatures.
-    animation_data_object = get_animation_data_object(context)
-    animation_data = animation_data_object.animation_data if animation_data_object else None
+    # TODO: this is cleared in the callback, although this should probably be changed.
+    # pg.nla_strip_list.clear()
+    
+    assert len(armature_objects) >= 0, 'Must have at least one armature object'
+
+    # TODO: for now, use the first armature object's animation data.
+    # animation_data_object = get_animation_data_object(context, pg)
+    armature_object = armature_objects[0]
+    animation_data = armature_object.animation_data if armature_object else None
 
     if animation_data is None:
         return
@@ -83,7 +94,7 @@ def update_actions_and_timeline_markers(context: Context, armature_objects: Iter
 
         for (name, frame_start, frame_end) in get_sequences_from_action(action):
             item = pg.action_list.add()
-            item.action = action
+            item.action_name = action.name
             item.name = name
             item.is_selected = False
             item.is_pose_marker = False
@@ -93,12 +104,10 @@ def update_actions_and_timeline_markers(context: Context, armature_objects: Iter
         # Pose markers are not guaranteed to be in frame-order, so make sure that they are.
         pose_markers = sorted(action.pose_markers, key=lambda x: x.frame)
         for pose_marker_index, pose_marker in enumerate(pose_markers):
-            if pose_marker.name.strip() == '' or pose_marker.name.startswith('#'):
-                continue
             sequences = get_sequences_from_action_pose_markers(action, pose_markers, pose_marker, pose_marker_index)
             for (name, frame_start, frame_end) in sequences:
                 item = pg.action_list.add()
-                item.action = action
+                item.action_name = action.name
                 item.name = name
                 item.is_selected = False
                 item.is_pose_marker = True
@@ -107,7 +116,7 @@ def update_actions_and_timeline_markers(context: Context, armature_objects: Iter
 
     # Populate timeline markers list.
     marker_names = [x.name for x in context.scene.timeline_markers]
-    sequence_frame_ranges = get_timeline_marker_sequence_frame_ranges(animation_data, context, marker_names)
+    sequence_frame_ranges = get_timeline_marker_sequence_frame_ranges(animation_data, context.scene, marker_names)
 
     for marker_name in marker_names:
         if marker_name not in sequence_frame_ranges:
@@ -124,30 +133,32 @@ def update_actions_and_timeline_markers(context: Context, armature_objects: Iter
             item.frame_end = frame_end
 
     # Populate the active action list.
-    for armature_object in context.selected_objects:
-        if armature_object.type != 'ARMATURE':
-            continue
-        action = armature_object.animation_data.action if armature_object.animation_data else None
-        if action is None:
+    for armature_object in armature_objects:
+        active_action = armature_object.animation_data.action if armature_object.animation_data else None
+        if active_action is None:
             continue
+        sequences = get_sequences_from_action(active_action)
+        for (sequence_name, frame_start, frame_end) in sequences:
+            # TODO: for some reason we aren't doing the sequence name parsing here.
             item = pg.active_action_list.add()
-        item.name = action.name
-        item.armature_object = armature_object
-        item.action = action
-        item.frame_start = int(item.action.frame_range[0])
-        item.frame_end = int(item.action.frame_range[1])
+            item.name = sequence_name
+            item.armature_object_name = armature_object.name
+            item.action_name = active_action.name
+            item.frame_start = frame_start
+            item.frame_end = frame_end
             item.is_selected = True
 
 
 def get_sequence_fps(context: Context, fps_source: str, fps_custom: float, actions: Iterable[Action]) -> float:
     match fps_source:
         case 'SCENE':
+            assert context.scene
             return context.scene.render.fps
         case 'CUSTOM':
             return fps_custom
         case 'ACTION_METADATA':
             # Get the minimum value of action metadata FPS values.
-            return min([action.psa_export.fps for action in actions])
+            return min([typing_cast(PSX_PG_action_export, getattr(action, 'psa_export')).fps for action in actions])
         case _:
             assert False, f'Invalid FPS source: {fps_source}'
 
@@ -160,41 +171,25 @@ def get_sequence_compression_ratio(
     match compression_ratio_source:
         case 'ACTION_METADATA':
             # Get the minimum value of action metadata compression ratio values.
-            return min(map(lambda action: action.psa_export.compression_ratio, actions))
+            return min(map(lambda action: typing_cast(PSX_PG_action_export, getattr(action, 'psa_export')).compression_ratio, actions))
         case 'CUSTOM':
             return compression_ratio_custom
         case _:
             assert False, f'Invalid compression ratio source: {compression_ratio_source}'
 
 
-def get_animation_data_object(context: Context) -> Object:
-    pg: PSA_PG_export = getattr(context.scene, 'psa_export')
-
-    active_object = context.view_layer.objects.active
-
-    if active_object is None or active_object.type != 'ARMATURE':
-        raise RuntimeError('Active object must be an Armature')
-
-    if pg.sequence_source != 'ACTIONS' and pg.should_override_animation_data:
-        animation_data_object = pg.animation_data_override
-    else:
-        animation_data_object = active_object
-
-    return animation_data_object
-
-
 def get_timeline_marker_sequence_frame_ranges(
         animation_data: AnimData, 
-        context: Context, 
-        marker_names: List[str],
-        ) -> Dict:
+        scene: Scene,
+        marker_names: list[str],
+        ) -> dict[str, tuple[int, int]]:
     # Timeline markers need to be sorted so that we can determine the sequence start and end positions.
-    sequence_frame_ranges = dict()
-    sorted_timeline_markers = list(sorted(context.scene.timeline_markers, key=lambda x: x.frame))
+    sequence_frame_ranges: dict[str, tuple[int, int]] = dict()
+    sorted_timeline_markers = list(sorted(scene.timeline_markers, key=lambda x: x.frame))
     sorted_timeline_marker_names = [x.name for x in sorted_timeline_markers]
 
     for marker_name in marker_names:
-        marker = context.scene.timeline_markers[marker_name]
+        marker = scene.timeline_markers[marker_name]
         frame_start = marker.frame
         # Determine the final frame of the sequence based on the next marker.
         # If no subsequent marker exists, use the maximum frame_end from all NLA strips.
@@ -247,12 +242,14 @@ def get_sequences_from_action(action: Action):
 
 def get_sequences_from_action_pose_markers(
         action: Action, 
-        pose_markers: List[TimelineMarker], 
+        pose_markers: list[TimelineMarker], 
         pose_marker: TimelineMarker, 
         pose_marker_index: int,
         ):
     frame_start = pose_marker.frame
     sequence_name = pose_marker.name
+    if pose_marker.name.strip() == '' or pose_marker.name.startswith('#'):
+        return
     if pose_marker.name.startswith('!'):
         # If the pose marker name starts with an exclamation mark, only export the first frame.
         frame_end = frame_start
@@ -264,7 +261,7 @@ def get_sequences_from_action_pose_markers(
     yield from get_sequences_from_name_and_frame_range(sequence_name, frame_start, frame_end)
 
 
-def get_visible_sequences(pg: PSA_PG_export, sequences) -> List[PSA_PG_export_action_list_item]:
+def get_visible_sequences(pg: PsaExportMixin, sequences) -> list[PsaExportSequenceMixin]:
     visible_sequences = []
     for i, flag in enumerate(filter_sequences(pg, sequences)):
         if bool(flag & (1 << 30)):
@@ -272,10 +269,11 @@ def get_visible_sequences(pg: PSA_PG_export, sequences) -> List[PSA_PG_export_ac
     return visible_sequences
 
 
-class PSA_OT_export(Operator, ExportHelper):
-    bl_idname = 'psa.export'
+
+class PSA_OT_export_collection(Operator, ExportHelper, PsaExportMixin):
+    bl_idname = 'psa.export_collection'
     bl_label = 'Export'
-    bl_options = {'INTERNAL', 'UNDO'}
+    bl_options = {'INTERNAL'}
     bl_description = 'Export actions to PSA'
     filename_ext = '.psa'
     filter_glob: StringProperty(default='*.psa', options={'HIDDEN'})
@@ -285,39 +283,114 @@ class PSA_OT_export(Operator, ExportHelper):
         maxlen=1024,
         default='')
 
-    def __init__(self, *args, **kwargs):
-        super().__init__(*args, **kwargs)
-        self.armature_objects: List[Object] = []
+    def execute(self, context: Context):
+        # TODO: get the armature objects from the collection export operator
+        collection = get_collection_from_context(context)
+        if collection is None:
+            self.report({'ERROR'}, 'No collection found for export')
+            return {'CANCELLED'}
 
-    @classmethod
-    def poll(cls, context):
         try:
-            cls._check_context(context)
+            import_objects = get_psk_input_objects_for_collection(collection)
         except RuntimeError as e:
-            cls.poll_message_set(str(e))
-            return False
-        return True
+            self.report({'ERROR_INVALID_CONTEXT'}, str(e))
+            return {'CANCELLED'}
 
-    def draw(self, context):
+        options = create_psa_export_options(context, import_objects.armature_objects, self)
+
+        if len(options.sequences) == 0:
+            self.report({'ERROR'}, 'No sequences were selected for export')
+            return {'CANCELLED'}
+
+        try:
+            psa = build_psa(context, options)
+            self.report({'INFO'}, f'PSA export successful')
+        except RuntimeError as e:
+            self.report({'ERROR_INVALID_CONTEXT'}, str(e))
+            return {'CANCELLED'}
+
+        write_psa_to_file(psa, self.filepath)
+
+        return {'FINISHED'}
+
+    def draw(self, context: Context):
         layout = self.layout
-        assert layout
-        pg = getattr(context.scene, 'psa_export')
 
+        assert layout is not None
+
+        flow = layout.grid_flow(row_major=True)
+        flow.use_property_split = True
+        flow.use_property_decorate = False
+
+        # Sequences
+        draw_sequences_panel(layout, self,
+                             PSA_OT_export_collection_sequences_select_all.bl_idname,
+                             PSA_OT_export_collection_sequences_deselect_all.bl_idname,
+                             )
+
+        # Bones
+        bones_header, bones_panel = layout.panel('Bones', default_closed=False)
+        bones_header.label(text='Bones', icon='BONE_DATA')
+        if bones_panel:
+            draw_bone_filter_mode(bones_panel, self, True)
+
+            if self.bone_filter_mode == 'BONE_COLLECTIONS':
+                row = bones_panel.row()
+                rows = max(3, min(len(self.bone_collection_list), 10))
+                row.template_list('PSX_UL_bone_collection_list', '', self, 'bone_collection_list', self, 'bone_collection_list_index', rows=rows)
+                col = row.column(align=True)
+                col.operator(PSK_OT_bone_collection_list_populate.bl_idname, text='', icon='FILE_REFRESH')
+                col.separator()
+                op = col.operator(PSK_OT_bone_collection_list_select_all.bl_idname, text='', icon='CHECKBOX_HLT')
+                op.is_selected = True
+                op = col.operator(PSK_OT_bone_collection_list_select_all.bl_idname, text='', icon='CHECKBOX_DEHLT')
+                op.is_selected = False
+
+        # Transform
+        transform_header, transform_panel = layout.panel('Transform', default_closed=False)
+        transform_header.label(text='Transform', icon='DRIVER_TRANSFORM')
+        if transform_panel:
+            flow = transform_panel.grid_flow(row_major=True)
+            flow.use_property_split = True
+            flow.use_property_decorate = False
+            flow.prop(self, 'export_space')
+            flow.prop(self, 'transform_source')
+
+            flow = transform_panel.grid_flow(row_major=True)
+            flow.use_property_split = True
+            flow.use_property_decorate = False
+
+            match self.transform_source:
+                case 'SCENE':
+                    transform_source = getattr(context.scene, 'psx_export')
+                    flow.enabled = False
+                case 'CUSTOM':
+                    transform_source = self
+                case _:
+                    assert False, f'Invalid transform source: {self.transform_source}'
+        
+            flow.prop(transform_source, 'scale')
+            flow.prop(transform_source, 'forward_axis')
+            flow.prop(transform_source, 'up_axis')
+
+
+def draw_sequences_panel(
+        layout: UILayout, 
+        pg: PsaExportMixin,
+        sequences_select_all_operator_idname: str,
+        sequences_deselect_all_operator_idname: str,
+        ):
     sequences_header, sequences_panel = layout.panel('Sequences', default_closed=False)
     sequences_header.label(text='Sequences', icon='ACTION')
 
     if sequences_panel:
+        sequences_panel.operator(PSA_OT_export_collection_populate_sequences.bl_idname, text='Refresh', icon='FILE_REFRESH')
+
         flow = sequences_panel.grid_flow()
         flow.use_property_split = True
         flow.use_property_decorate = False
         flow.prop(pg, 'sequence_source', text='Source')
 
-            if pg.sequence_source in {'TIMELINE_MARKERS', 'NLA_TRACK_STRIPS'}:
-                # ANIMDATA SOURCE
-                flow.prop(pg, 'should_override_animation_data')
-                if pg.should_override_animation_data:
-                    flow.prop(pg, 'animation_data_override', text=' ')
-
         if pg.sequence_source == 'NLA_TRACK_STRIPS':
             flow = sequences_panel.grid_flow()
             flow.use_property_split = True
@@ -327,8 +400,8 @@ class PSA_OT_export(Operator, ExportHelper):
         # SELECT ALL/NONE
         row = sequences_panel.row(align=True)
         row.label(text='Select')
-            row.operator(PSA_OT_export_actions_select_all.bl_idname, text='All', icon='CHECKBOX_HLT')
-            row.operator(PSA_OT_export_actions_deselect_all.bl_idname, text='None', icon='CHECKBOX_DEHLT')
+        row.operator(sequences_select_all_operator_idname, text='All', icon='CHECKBOX_HLT')
+        row.operator(sequences_deselect_all_operator_idname, text='None', icon='CHECKBOX_DEHLT')
 
         propname, active_propname = get_sequences_propnames_from_source(pg.sequence_source)
         sequences_panel.template_list(PSA_UL_export_sequences.bl_idname, '', pg, propname, pg, active_propname,
@@ -386,6 +459,145 @@ class PSA_OT_export(Operator, ExportHelper):
             if pg.compression_ratio_source == 'CUSTOM':
                 col.prop(pg, 'compression_ratio_custom', text='')
 
+
+def create_psa_export_options(context: Context, armature_objects: Sequence[Object], pg: PsaExportMixin) -> PsaBuildOptions:
+    if len(armature_objects) == 0:
+        raise RuntimeError(f'No armatures')
+
+    animation_data = armature_objects[0].animation_data
+    export_sequences: list[PsaBuildSequence] = []
+
+    # TODO: this needs to be changed so that we iterate over all of the armature objects?
+    # do we need to check for primary key? (data vs. object?)
+
+    def get_export_sequence_group(group_source: str, group_custom: str | None, action: Action | None) -> str | None:
+        match group_source:
+            case 'ACTIONS':
+                if action is None:
+                    return None
+                action_psa_export = typing_cast(PSX_PG_action_export, getattr(action, 'psa_export'))
+                return action_psa_export.group
+            case 'CUSTOM':
+                return group_custom
+            case _:
+                return None
+
+    match pg.sequence_source:
+        case 'ACTIONS':
+            for action_item in filter(lambda x: x.is_selected, pg.action_list):
+                if action_item.action is None:
+                    continue
+                if len(action_item.action.layers) == 0:
+                    continue
+                export_sequence = PsaBuildSequence(context.active_object, animation_data)
+                export_sequence.name = action_item.name
+                export_sequence.group = get_export_sequence_group(pg.group_source, pg.group_custom, action_item.action)
+                export_sequence.nla_state.action = action_item.action
+                export_sequence.nla_state.frame_start = action_item.frame_start
+                export_sequence.nla_state.frame_end = action_item.frame_end
+                export_sequence.fps = get_sequence_fps(context, pg.fps_source, pg.fps_custom, [action_item.action])
+                export_sequence.compression_ratio = get_sequence_compression_ratio(pg.compression_ratio_source, pg.compression_ratio_custom, [action_item.action])
+                export_sequence.key_quota = action_item.action.psa_export.key_quota
+                export_sequences.append(export_sequence)
+        case 'TIMELINE_MARKERS':
+            for marker_item in filter(lambda x: x.is_selected, pg.marker_list):
+                nla_strips_actions: list[Action] = []
+                for nla_strip in get_nla_strips_in_frame_range(animation_data, marker_item.frame_start, marker_item.frame_end):
+                    if nla_strip.action:
+                        nla_strips_actions.append(nla_strip.action)
+                export_sequence = PsaBuildSequence(context.active_object, animation_data)
+                export_sequence.name = marker_item.name
+                export_sequence.group = get_export_sequence_group(pg.group_source, pg.group_custom, next(iter(nla_strips_actions), None))
+                export_sequence.nla_state.frame_start = marker_item.frame_start
+                export_sequence.nla_state.frame_end = marker_item.frame_end
+                export_sequence.fps = get_sequence_fps(context, pg.fps_source, pg.fps_custom, nla_strips_actions)
+                export_sequence.compression_ratio = get_sequence_compression_ratio(pg.compression_ratio_source, pg.compression_ratio_custom, nla_strips_actions)
+                export_sequences.append(export_sequence)
+        case 'NLA_TRACK_STRIPS':
+            for nla_strip_item in filter(lambda x: x.is_selected, pg.nla_strip_list):
+                if nla_strip_item.action is None:
+                    continue
+                export_sequence = PsaBuildSequence(context.active_object, animation_data)
+                export_sequence.name = nla_strip_item.name
+                export_sequence.group = get_export_sequence_group(pg.group_source, pg.group_custom, nla_strip_item.action)
+                export_sequence.nla_state.frame_start = nla_strip_item.frame_start
+                export_sequence.nla_state.frame_end = nla_strip_item.frame_end
+                export_sequence.fps = get_sequence_fps(context, pg.fps_source, pg.fps_custom, [nla_strip_item.action])
+                export_sequence.compression_ratio = get_sequence_compression_ratio(pg.compression_ratio_source, pg.compression_ratio_custom, [nla_strip_item.action])
+                export_sequence.key_quota = nla_strip_item.action.psa_export.key_quota
+                export_sequences.append(export_sequence)
+        case 'ACTIVE_ACTION':
+            for active_action_item in filter(lambda x: x.is_selected, pg.active_action_list):
+                export_sequence = PsaBuildSequence(active_action_item.armature_object, active_action_item.armature_object.animation_data)
+                action = active_action_item.action
+                if action is None:
+                    continue
+                export_sequence.name = action.name
+                export_sequence.group = get_export_sequence_group(pg.group_source, pg.group_custom, action)
+                export_sequence.nla_state.action = action
+                export_sequence.nla_state.frame_start = int(action.frame_range[0])
+                export_sequence.nla_state.frame_end = int(action.frame_range[1])
+                export_sequence.fps = get_sequence_fps(context, pg.fps_source, pg.fps_custom, [action])
+                export_sequence.compression_ratio = get_sequence_compression_ratio(pg.compression_ratio_source, pg.compression_ratio_custom, [action])
+                export_sequence.key_quota = action.psa_export.key_quota
+                export_sequences.append(export_sequence)
+        case _:
+            assert False, f'Invalid sequence source: {pg.sequence_source}'
+
+    options = PsaBuildOptions()
+    options.armature_objects = list(armature_objects)
+    options.animation_data = animation_data
+    options.sequences = export_sequences
+    options.bone_filter_mode = pg.bone_filter_mode
+    options.bone_collection_indices = [PsxBoneCollection(x.armature_object_name, x.armature_data_name, x.index) for x in pg.bone_collection_list if x.is_selected]
+    options.sequence_name_prefix = pg.sequence_name_prefix
+    options.sequence_name_suffix = pg.sequence_name_suffix
+    options.sampling_mode = pg.sampling_mode
+    options.export_space = pg.export_space
+    options.scale = pg.scale
+    options.forward_axis = pg.forward_axis
+    options.up_axis = pg.up_axis
+    options.sequence_source = pg.sequence_source
+
+    return options
+
+
+class PSA_OT_export(Operator, ExportHelper):
+    bl_idname = 'psa.export'
+    bl_label = 'Export'
+    bl_options = {'INTERNAL'}
+    bl_description = 'Export actions to PSA'
+    filename_ext = '.psa'
+    filter_glob: StringProperty(default='*.psa', options={'HIDDEN'})
+    filepath: StringProperty(
+        name='File Path',
+        description='File path used for exporting the PSA file',
+        maxlen=1024,
+        default='')
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        self.armature_objects: list[Object] = []
+
+    @classmethod
+    def poll(cls, context):
+        try:
+            cls._check_context(context)
+        except RuntimeError as e:
+            cls.poll_message_set(str(e))
+            return False
+        return True
+
+    def draw(self, context):
+        layout = self.layout
+        assert layout
+        pg = typing_cast(PSA_PG_export, getattr(context.scene, 'psa_export'))
+
+        # SEQUENCES
+        draw_sequences_panel(layout, pg,
+                             PSA_OT_export_sequences_select_all.bl_idname, 
+                             PSA_OT_export_sequences_deselect_all.bl_idname)
+
         # BONES
         bones_header, bones_panel = layout.panel('Bones', default_closed=False)
         bones_header.label(text='Bones', icon='BONE_DATA')
@@ -405,17 +617,9 @@ class PSA_OT_export(Operator, ExportHelper):
                     rows=rows
                     )
 
-            bones_advanced_header, bones_advanced_panel = layout.panel('Bones Advanced', default_closed=True)
-            bones_advanced_header.label(text='Advanced')
-            if bones_advanced_panel:
-                flow = bones_advanced_panel.grid_flow()
-                flow.use_property_split = True
-                flow.use_property_decorate = False
-                flow.prop(pg, 'root_bone_name', text='Root Bone Name')
-
         # TRANSFORM
         transform_header, transform_panel = layout.panel('Advanced', default_closed=False)
-        transform_header.label(text='Transform')
+        transform_header.label(text='Transform', icon='DRIVER_TRANSFORM')
 
         if transform_panel:
             flow = transform_panel.grid_flow(row_major=True)
@@ -437,8 +641,7 @@ class PSA_OT_export(Operator, ExportHelper):
         if context.scene.is_nla_tweakmode:
             raise RuntimeError('Cannot export PSA while in NLA tweak mode')
 
-
-    def invoke(self, context, _event):
+    def invoke(self, context, event):
         try:
             self._check_context(context)
         except RuntimeError as e:
@@ -447,6 +650,8 @@ class PSA_OT_export(Operator, ExportHelper):
 
         pg: PSA_PG_export = getattr(context.scene, 'psa_export')
 
+        assert context.view_layer is not None
+
         self.armature_objects = [x for x in context.view_layer.objects.selected if x.type == 'ARMATURE']
 
         for armature_object in self.armature_objects:
@@ -455,117 +660,28 @@ class PSA_OT_export(Operator, ExportHelper):
             if armature_object.animation_data is None:
                 armature_object.animation_data_create()
 
-        update_actions_and_timeline_markers(context, self.armature_objects)
+
+        pg = getattr(context.scene, 'psa_export')
+        update_actions_and_timeline_markers(context, self.armature_objects, pg)
         populate_bone_collection_list(
             pg.bone_collection_list,
             self.armature_objects,
             primary_key='DATA' if pg.sequence_source == 'ACTIVE_ACTION' else 'OBJECT',
             )
 
+        if context.window_manager is not None:
             context.window_manager.fileselect_add(self)
 
         return {'RUNNING_MODAL'}
 
     def execute(self, context):
         pg = typing_cast(PSA_PG_export, getattr(context.scene, 'psa_export'))
+        options = create_psa_export_options(context, self.armature_objects, pg)
 
-        # Populate the export sequence list.
-        animation_data_object = get_animation_data_object(context)
-        animation_data = animation_data_object.animation_data
-
-        if animation_data is None:
-            raise RuntimeError(f'No animation data for object \'{animation_data_object.name}\'')
-        
-        if context.active_object is None:
-            raise RuntimeError('No active object')
-
-        export_sequences: List[PsaBuildSequence] = []
-
-        def get_export_sequence_group(group_source: str, group_custom: str | None, action: Action | None) -> str | None:
-            match group_source:
-                case 'ACTIONS':
-                    return action.psa_export.group if action else None
-                case 'CUSTOM':
-                    return group_custom
-                case _:
-                    return None
-
-        match pg.sequence_source:
-            case 'ACTIONS':
-                for action_item in filter(lambda x: x.is_selected, pg.action_list):
-                    if len(action_item.action.layers) == 0:
-                        continue
-                    export_sequence = PsaBuildSequence(context.active_object, animation_data)
-                    export_sequence.name = action_item.name
-                    export_sequence.group = get_export_sequence_group(pg.group_source, pg.group_custom, action_item.action)
-                    export_sequence.nla_state.action = action_item.action
-                    export_sequence.nla_state.frame_start = action_item.frame_start
-                    export_sequence.nla_state.frame_end = action_item.frame_end
-                    export_sequence.fps = get_sequence_fps(context, pg.fps_source, pg.fps_custom, [action_item.action])
-                    export_sequence.compression_ratio = get_sequence_compression_ratio(pg.compression_ratio_source, pg.compression_ratio_custom, [action_item.action])
-                    export_sequence.key_quota = action_item.action.psa_export.key_quota
-                    export_sequences.append(export_sequence)
-            case 'TIMELINE_MARKERS':
-                for marker_item in filter(lambda x: x.is_selected, pg.marker_list):
-                    nla_strips_actions: List[Action] = []
-                    for nla_strip in get_nla_strips_in_frame_range(animation_data, marker_item.frame_start, marker_item.frame_end):
-                        if nla_strip.action:
-                            nla_strips_actions.append(nla_strip.action)
-                    export_sequence = PsaBuildSequence(context.active_object, animation_data)
-                    export_sequence.name = marker_item.name
-                    export_sequence.group = get_export_sequence_group(pg.group_source, pg.group_custom, next(iter(nla_strips_actions), None))
-                    export_sequence.nla_state.frame_start = marker_item.frame_start
-                    export_sequence.nla_state.frame_end = marker_item.frame_end
-                    export_sequence.fps = get_sequence_fps(context, pg.fps_source, pg.fps_custom, nla_strips_actions)
-                    export_sequence.compression_ratio = get_sequence_compression_ratio(pg.compression_ratio_source, pg.compression_ratio_custom, nla_strips_actions)
-                    export_sequences.append(export_sequence)
-            case 'NLA_TRACK_STRIPS':
-                for nla_strip_item in filter(lambda x: x.is_selected, pg.nla_strip_list):
-                    export_sequence = PsaBuildSequence(context.active_object, animation_data)
-                    export_sequence.name = nla_strip_item.name
-                    export_sequence.group = get_export_sequence_group(pg.group_source, pg.group_custom, nla_strip_item.action)
-                    export_sequence.nla_state.frame_start = nla_strip_item.frame_start
-                    export_sequence.nla_state.frame_end = nla_strip_item.frame_end
-                    export_sequence.fps = get_sequence_fps(context, pg.fps_source, pg.fps_custom, [nla_strip_item.action])
-                    export_sequence.compression_ratio = get_sequence_compression_ratio(pg.compression_ratio_source, pg.compression_ratio_custom, [nla_strip_item.action])
-                    export_sequence.key_quota = nla_strip_item.action.psa_export.key_quota
-                    export_sequences.append(export_sequence)
-            case 'ACTIVE_ACTION':
-                for active_action_item in filter(lambda x: x.is_selected, pg.active_action_list):
-                    export_sequence = PsaBuildSequence(active_action_item.armature_object, active_action_item.armature_object.animation_data)
-                    action = active_action_item.action
-                    export_sequence.name = action.name
-                    export_sequence.group = get_export_sequence_group(pg.group_source, pg.group_custom, action)
-                    export_sequence.nla_state.action = action
-                    export_sequence.nla_state.frame_start = int(action.frame_range[0])
-                    export_sequence.nla_state.frame_end = int(action.frame_range[1])
-                    export_sequence.fps = get_sequence_fps(context, pg.fps_source, pg.fps_custom, [action])
-                    export_sequence.compression_ratio = get_sequence_compression_ratio(pg.compression_ratio_source, pg.compression_ratio_custom, [action])
-                    export_sequence.key_quota = action.psa_export.key_quota
-                    export_sequences.append(export_sequence)
-            case _:
-                assert False, f'Invalid sequence source: {pg.sequence_source}'
-
-        if len(export_sequences) == 0:
+        if len(options.sequences) == 0:
             self.report({'ERROR'}, 'No sequences were selected for export')
             return {'CANCELLED'}
 
-        options = PsaBuildOptions()
-        options.armature_objects = self.armature_objects
-        options.animation_data = animation_data
-        options.sequences = export_sequences
-        options.bone_filter_mode = pg.bone_filter_mode
-        options.bone_collection_indices = [PsxBoneCollection(x.armature_object_name, x.armature_data_name, x.index) for x in pg.bone_collection_list if x.is_selected]
-        options.sequence_name_prefix = pg.sequence_name_prefix
-        options.sequence_name_suffix = pg.sequence_name_suffix
-        options.sampling_mode = pg.sampling_mode
-        options.export_space = pg.export_space
-        options.scale = pg.scale
-        options.forward_axis = pg.forward_axis
-        options.up_axis = pg.up_axis
-        options.root_bone_name = pg.root_bone_name
-        options.sequence_source = pg.sequence_source
-
         try:
             psa = build_psa(context, options)
             self.report({'INFO'}, f'PSA export successful')
@@ -578,15 +694,15 @@ class PSA_OT_export(Operator, ExportHelper):
         return {'FINISHED'}
 
 
-class PSA_OT_export_actions_select_all(Operator):
-    bl_idname = 'psa.export_actions_select_all'
-    bl_label = 'Select All'
-    bl_description = 'Select all visible sequences'
-    bl_options = {'INTERNAL'}
+class PsaExportActionsSelectOperator(Operator):
+    @classmethod
+    @abstractmethod
+    def get_psa_export(cls, context: Context) -> PsaExportMixin:
+        pass
 
     @classmethod
-    def get_item_list(cls, context):
-        pg = context.scene.psa_export
+    def get_item_list(cls, context: Context):
+        pg = cls.get_psa_export(context)
         match pg.sequence_source:
             case 'ACTIONS':
                 return pg.action_list
@@ -599,49 +715,40 @@ class PSA_OT_export_actions_select_all(Operator):
             case _:
                 assert False, f'Invalid sequence source: {pg.sequence_source}'
 
-    @classmethod
-    def poll(cls, context):
-        pg = getattr(context.scene, 'psa_export')
-        item_list = cls.get_item_list(context)
-        visible_sequences = get_visible_sequences(pg, item_list)
-        has_unselected_sequences = any(map(lambda item: not item.is_selected, visible_sequences))
-        return has_unselected_sequences
-
+class PsaExportActionsSelectAllOperator(PsaExportActionsSelectOperator):
     def execute(self, context):
-        pg = getattr(context.scene, 'psa_export')
+        pg = self.__class__.get_psa_export(context)
         sequences = self.get_item_list(context)
         for sequence in get_visible_sequences(pg, sequences):
             sequence.is_selected = True
         return {'FINISHED'}
 
 
-class PSA_OT_export_actions_deselect_all(Operator):
-    bl_idname = 'psa.export_sequences_deselect_all'
-    bl_label = 'Deselect All'
-    bl_description = 'Deselect all visible sequences'
+class PSA_OT_export_sequences_select_all(PsaExportActionsSelectAllOperator):
+    bl_idname = 'psa.export_actions_select_all'
+    bl_label = 'Select All'
+    bl_description = 'Select all visible sequences'
     bl_options = {'INTERNAL'}
 
     @classmethod
-    def get_item_list(cls, context):
-        pg = context.scene.psa_export
-        match pg.sequence_source:
-            case 'ACTIONS':
-                return pg.action_list
-            case 'TIMELINE_MARKERS':
-                return pg.marker_list
-            case 'NLA_TRACK_STRIPS':
-                return pg.nla_strip_list
-            case 'ACTIVE_ACTION':
-                return pg.active_action_list
-            case _:
-                return None
+    def get_psa_export(cls, context: Context) -> PsaExportMixin:
+        return typing_cast(PsaExportMixin, getattr(context.scene, 'psa_export'))
+
+
+class PSA_OT_export_collection_sequences_select_all(PsaExportActionsSelectAllOperator):
+    bl_idname = 'psa.export_collection_sequences_select_all'
+    bl_label = 'Select All'
+    bl_description = 'Select all visible sequences'
+    bl_options = {'INTERNAL'}
 
     @classmethod
-    def poll(cls, context):
-        item_list = cls.get_item_list(context)
-        has_selected_items = any(map(lambda item: item.is_selected, item_list))
-        return len(item_list) > 0 and has_selected_items
+    def get_psa_export(cls, context: Context) -> PsaExportMixin:
+        operator = get_collection_export_operator_from_context(context)
+        operator = typing_cast(PsaExportMixin, operator)
+        return operator
 
+
+class PsaExportActionsDeselectAllOperator(PsaExportActionsSelectOperator):
     def execute(self, context):
         pg = getattr(context.scene, 'psa_export')
         item_list = self.get_item_list(context)
@@ -650,6 +757,30 @@ class PSA_OT_export_actions_deselect_all(Operator):
         return {'FINISHED'}
 
 
+class PSA_OT_export_collection_sequences_deselect_all(PsaExportActionsDeselectAllOperator):
+    bl_idname = 'psa.export_collection_sequences_deselect_all'
+    bl_label = 'Deselect All'
+    bl_description = 'Deselect all visible sequences'
+    bl_options = {'INTERNAL'}
+
+    @classmethod
+    def get_psa_export(cls, context: Context) -> PsaExportMixin:
+        operator = get_collection_export_operator_from_context(context)
+        operator = typing_cast(PsaExportMixin, operator)
+        return operator
+
+
+class PSA_OT_export_sequences_deselect_all(PsaExportActionsDeselectAllOperator):
+    bl_idname = 'psa.export_sequences_deselect_all'
+    bl_label = 'Deselect All'
+    bl_description = 'Deselect all visible sequences'
+    bl_options = {'INTERNAL'}
+
+    @classmethod
+    def get_psa_export(cls, context: Context) -> PsaExportMixin:
+        return typing_cast(PsaExportMixin, getattr(context.scene, 'psa_export'))
+
+
 class PSA_OT_export_bone_collections_select_all(Operator):
     bl_idname = 'psa.export_bone_collections_select_all'
     bl_label = 'Select All'
@@ -658,13 +789,13 @@ class PSA_OT_export_bone_collections_select_all(Operator):
 
     @classmethod
     def poll(cls, context):
-        pg = getattr(context.scene, 'psa_export')
+        pg = typing_cast(PSA_PG_export, getattr(context.scene, 'psa_export'))
         item_list = pg.bone_collection_list
         has_unselected_items = any(map(lambda action: not action.is_selected, item_list))
         return len(item_list) > 0 and has_unselected_items
 
     def execute(self, context):
-        pg = getattr(context.scene, 'psa_export')
+        pg = typing_cast(PSA_PG_export, getattr(context.scene, 'psa_export'))
         for item in pg.bone_collection_list:
             item.is_selected = True
         return {'FINISHED'}
@@ -678,24 +809,72 @@ class PSA_OT_export_bone_collections_deselect_all(Operator):
 
     @classmethod
     def poll(cls, context):
-        pg = getattr(context.scene, 'psa_export')
+        pg = typing_cast(PSA_PG_export, getattr(context.scene, 'psa_export'))
         item_list = pg.bone_collection_list
         has_selected_actions = any(map(lambda action: action.is_selected, item_list))
         return len(item_list) > 0 and has_selected_actions
 
     def execute(self, context):
-        pg = getattr(context.scene, 'psa_export')
+        pg = typing_cast(PSA_PG_export, getattr(context.scene, 'psa_export'))
         for action in pg.bone_collection_list:
             action.is_selected = False
         return {'FINISHED'}
 
 
+class PSA_OT_export_collection_populate_sequences(Operator):
+    bl_idname = 'psa.export_collection_populate_sequences'
+    bl_label = 'Populate Sequences'
+    bl_description = 'Populate the sequences list based on the armatures in the collection'
+    bl_options = {'INTERNAL'}
+
+    def execute(self, context: Context):
+        export_operator = get_collection_export_operator_from_context(context)
+        assert export_operator is not None
+        export_operator = typing_cast(PSA_OT_export_collection, export_operator)
+        collection = get_collection_from_context(context)
+        if collection is None:
+            self.report({'ERROR'}, 'No collection found in context')
+            return {'CANCELLED'}
+        
+        try:
+            input_objects = get_psk_input_objects_for_collection(collection)
+        except RuntimeError as e:
+            self.report({'ERROR_INVALID_CONTEXT'}, str(e))
+            return {'CANCELLED'}
+
+        # Keep track of what sequences were selected, then restore the selected status after we have updated the lists.
+        def store_is_selected_for_sequence_list(sequences: Iterable[PsaExportSequenceMixin]) -> dict[int, bool]:
+            return {hash(x): x.is_selected for x in sequences}
+    
+        def restore_is_selected_for_sequence_list(sequence_list: Iterable[PsaExportSequenceMixin], is_selected_map: dict[int, bool]):
+            for sequence in sequence_list:
+                sequence.is_selected = is_selected_map.get(hash(sequence), False)
+
+        action_list_is_selected = store_is_selected_for_sequence_list(export_operator.action_list)
+        markers_list_is_selected = store_is_selected_for_sequence_list(export_operator.marker_list)
+        nla_strip_list_is_selected = store_is_selected_for_sequence_list(export_operator.nla_strip_list)
+        active_action_list_is_selected = store_is_selected_for_sequence_list(export_operator.active_action_list)
+
+        update_actions_and_timeline_markers(context, input_objects.armature_objects, export_operator)
+
+        restore_is_selected_for_sequence_list(export_operator.action_list, action_list_is_selected)
+        restore_is_selected_for_sequence_list(export_operator.marker_list, markers_list_is_selected)
+        restore_is_selected_for_sequence_list(export_operator.nla_strip_list, nla_strip_list_is_selected)
+        restore_is_selected_for_sequence_list(export_operator.active_action_list, active_action_list_is_selected)
+        
+        return {'FINISHED'}
+
+
 _classes = (
     PSA_OT_export,
-    PSA_OT_export_actions_select_all,
-    PSA_OT_export_actions_deselect_all,
+    PSA_OT_export_collection,
+    PSA_OT_export_sequences_select_all,
+    PSA_OT_export_sequences_deselect_all,
+    PSA_OT_export_collection_sequences_select_all,
+    PSA_OT_export_collection_sequences_deselect_all,
     PSA_OT_export_bone_collections_select_all,
     PSA_OT_export_bone_collections_deselect_all,
+    PSA_OT_export_collection_populate_sequences,
 )
 
 from bpy.utils import register_classes_factory

io_scene_psk_psa/psa/export/properties.py

@@ -1,10 +1,10 @@
 import re
 import sys
 from fnmatch import fnmatch
-from typing import List, Optional
+from typing import Sequence
+import bpy
 from bpy.props import (
     BoolProperty,
-    PointerProperty,
     EnumProperty,
     FloatProperty,
     CollectionProperty,
@@ -15,52 +15,69 @@ from bpy.types import PropertyGroup, Object, Action, AnimData, Context
 
 from ...shared.dfs import dfs_view_layer_objects
 from ...shared.helpers import populate_bone_collection_list
-from ...shared.types import TransformMixin, ExportSpaceMixin, PsxBoneExportMixin
+from ...shared.types import TransformMixin, ExportSpaceMixin, PsxBoneExportMixin, TransformSourceMixin
 
 
 def psa_export_property_group_animation_data_override_poll(_context, obj):
     return obj.animation_data is not None
 
 
-class PSA_PG_export_action_list_item(PropertyGroup):
-    action: PointerProperty(type=Action)
-    name: StringProperty()
-    is_selected: BoolProperty(default=True)
-    frame_start: IntProperty(options={'HIDDEN'})
-    frame_end: IntProperty(options={'HIDDEN'})
-    is_pose_marker: BoolProperty(options={'HIDDEN'})
-    group: StringProperty()
+class PsaExportSequenceMixin(PropertyGroup):
+    name: StringProperty(name='Name')
+    is_selected: BoolProperty(name='Selected', default=True)
+    frame_start: IntProperty(name='Start Frame', options={'HIDDEN'})
+    frame_end: IntProperty(name='End Frame', options={'HIDDEN'})
+    group: StringProperty(name='Group')
+    action_name: StringProperty(name='Action Name',default='', options={'HIDDEN'})
+    armature_object_name: StringProperty(name='Armature Object Name',default='', options={'HIDDEN'})
+    marker_index: IntProperty(name='Marker Index',default=-1, options={'HIDDEN'})
+    is_pose_marker: BoolProperty(name='Is Pose Marker',default=False, options={'HIDDEN'})
+
+    @property
+    def action(self) -> Action | None:
+        """Get the action associated with this sequence (if any)."""
+        return bpy.data.actions.get(self.action_name) if self.action_name else None
+
+    @property
+    def armature_object(self) -> Object | None:
+        """Get the armature object associated with this sequence (if any)."""
+        return bpy.data.objects.get(self.armature_object_name) if self.armature_object_name else None
+    
+    @property
+    def is_reversed(self) -> bool:
+        """Check if the sequence is reversed (end frame before start frame)."""
+        return self.frame_end < self.frame_start
+
+    def __hash__(self) -> int:
+        return hash(self.name)
 
 
-class PSA_PG_export_active_action_list_item(PropertyGroup):
-    action: PointerProperty(type=Action)
-    name: StringProperty()
-    armature_object: PointerProperty(type=Object)
-    is_selected: BoolProperty(default=True)
-    frame_start: IntProperty(options={'HIDDEN'})
-    frame_end: IntProperty(options={'HIDDEN'})
-    group: StringProperty()
-
-
-class PSA_PG_export_timeline_markers(PropertyGroup):  # TODO: rename this to singular
-    marker_index: IntProperty()
-    name: StringProperty()
-    is_selected: BoolProperty(default=True)
-    frame_start: IntProperty(options={'HIDDEN'})
-    frame_end: IntProperty(options={'HIDDEN'})
-    group: StringProperty()
-
-
-class PSA_PG_export_nla_strip_list_item(PropertyGroup):
-    name: StringProperty()
-    action: PointerProperty(type=Action)
-    frame_start: FloatProperty()
-    frame_end: FloatProperty()
-    is_selected: BoolProperty(default=True)
-    group: StringProperty()
+class PSA_PG_export_sequence(PsaExportSequenceMixin):
+    pass
 
 
 def get_sequences_from_name_and_frame_range(name: str, frame_start: int, frame_end: int):
+    # Check for loop
+    anims: list[tuple[str, int, int]] = []
+    loop_pattern = r'\@(\d+)\:(.+)'
+    loop_match = re.match(loop_pattern, name)
+    if loop_match:
+        frame_count = max(1, int(loop_match.group(1)))
+        sequence_name = loop_match.group(2)
+        iteration = 0
+        frame = frame_start
+        while frame + frame_count <= frame_end:
+            output_name = sequence_name.format(index=iteration)
+            iteration_frame_start = frame
+            iteration_frame_end = frame + frame_count - 1
+            anims.append((output_name, iteration_frame_start, iteration_frame_end))
+            frame += frame_count
+            iteration += 1
+    else:
+        # If not, just treat it as a single animation, but parse for the reverse pattern as well.
+        anims.append((name, frame_start, frame_end))
+
+    for (name, frame_start, frame_end) in anims:
         reversed_pattern = r'(.+)/(.+)'
         reversed_match = re.match(reversed_pattern, name)
         if reversed_match:
@@ -83,17 +100,15 @@ def nla_track_update_cb(self: 'PSA_PG_export', context: Context) -> None:
         nla_track = animation_data.nla_tracks[self.nla_track_index]
         for nla_strip in nla_track.strips:
             for sequence_name, frame_start, frame_end in get_sequences_from_name_and_frame_range(nla_strip.name, nla_strip.frame_start, nla_strip.frame_end):
-                strip: PSA_PG_export_nla_strip_list_item = self.nla_strip_list.add()
-                strip.action = nla_strip.action
+                strip: PSA_PG_export_sequence = self.nla_strip_list.add()
+                strip.action_name = nla_strip.action
                 strip.name = sequence_name
                 strip.frame_start = frame_start
                 strip.frame_end = frame_end
 
 
-def get_animation_data(pg: 'PSA_PG_export', context: Context) -> Optional[AnimData]:
+def get_animation_data(pg: 'PSA_PG_export', context: Context) -> AnimData | None:
     animation_data_object = context.object
-    if pg.should_override_animation_data:
-        animation_data_object = pg.animation_data_override
     return animation_data_object.animation_data if animation_data_object else None
 
 
@@ -152,19 +167,7 @@ def sequence_source_update_cb(self: 'PSA_PG_export', context: Context) -> None:
         primary_key='DATA' if self.sequence_source == 'ACTIVE_ACTION' else 'OBJECT')
 
 
-class PSA_PG_export(PropertyGroup, TransformMixin, ExportSpaceMixin, PsxBoneExportMixin):
-    should_override_animation_data: BoolProperty(
-        name='Override Animation Data',
-        options=set(),
-        default=False,
-        description='Use the animation data from a different object instead of the selected object',
-        update=animation_data_override_update_cb,
-    )
-    animation_data_override: PointerProperty(
-        type=Object,
-        update=animation_data_override_update_cb,
-        poll=psa_export_property_group_animation_data_override_poll
-    )
+class PsaExportMixin(PropertyGroup, TransformMixin, ExportSpaceMixin, PsxBoneExportMixin, TransformSourceMixin):
     sequence_source: EnumProperty(
         name='Source',
         options=set(),
@@ -194,14 +197,16 @@ class PSA_PG_export(PropertyGroup, TransformMixin, ExportSpaceMixin, PsxBoneExpo
         items=compression_ratio_source_items,
     )
     compression_ratio_custom: FloatProperty(default=1.0, min=0.0, max=1.0, subtype='FACTOR', description='The key sampling ratio of the exported sequence.\n\nA compression ratio of 1.0 will export all frames, while a compression ratio of 0.5 will export half of the frames')
-    action_list: CollectionProperty(type=PSA_PG_export_action_list_item)
+
+    action_list: CollectionProperty(type=PSA_PG_export_sequence)
     action_list_index: IntProperty(default=0)
-    marker_list: CollectionProperty(type=PSA_PG_export_timeline_markers)
+    marker_list: CollectionProperty(type=PSA_PG_export_sequence)
     marker_list_index: IntProperty(default=0)
-    nla_strip_list: CollectionProperty(type=PSA_PG_export_nla_strip_list_item)
+    nla_strip_list: CollectionProperty(type=PSA_PG_export_sequence)
     nla_strip_list_index: IntProperty(default=0)
-    active_action_list: CollectionProperty(type=PSA_PG_export_active_action_list_item)
+    active_action_list: CollectionProperty(type=PSA_PG_export_sequence)
     active_action_list_index: IntProperty(default=0)
+
     sequence_name_prefix: StringProperty(name='Prefix', options=set())
     sequence_name_suffix: StringProperty(name='Suffix', options=set())
     sequence_filter_name: StringProperty(
@@ -250,8 +255,11 @@ class PSA_PG_export(PropertyGroup, TransformMixin, ExportSpaceMixin, PsxBoneExpo
         description='The group to apply to all exported sequences. Only applicable when Group Source is Custom.'
     )
 
+class PSA_PG_export(PsaExportMixin):
+    pass
 
-def filter_sequences(pg: PSA_PG_export, sequences) -> List[int]:
+
+def filter_sequences(pg: PsaExportMixin, sequences: Sequence[PsaExportSequenceMixin]) -> list[int]:
     bitflag_filter_item = 1 << 30
     flt_flags = [bitflag_filter_item] * len(sequences)
 
@@ -268,27 +276,24 @@ def filter_sequences(pg: PSA_PG_export, sequences) -> List[int]:
 
     if not pg.sequence_filter_asset:
         for i, sequence in enumerate(sequences):
-            if hasattr(sequence, 'action') and sequence.action is not None and sequence.action.asset_data is not None:
+            if sequence.action is not None and sequence.action.asset_data is not None:
                 flt_flags[i] &= ~bitflag_filter_item
 
     if not pg.sequence_filter_pose_marker:
         for i, sequence in enumerate(sequences):
-            if hasattr(sequence, 'is_pose_marker') and sequence.is_pose_marker:
+            if sequence.is_pose_marker:
                 flt_flags[i] &= ~bitflag_filter_item
 
     if not pg.sequence_filter_reversed:
         for i, sequence in enumerate(sequences):
-            if sequence.frame_start > sequence.frame_end:
+            if sequence.is_reversed:
                 flt_flags[i] &= ~bitflag_filter_item
 
     return flt_flags
 
 
 _classes = (
-    PSA_PG_export_action_list_item,
-    PSA_PG_export_timeline_markers,
-    PSA_PG_export_nla_strip_list_item,
-    PSA_PG_export_active_action_list_item,
+    PSA_PG_export_sequence,
     PSA_PG_export,
 )
 

io_scene_psk_psa/psa/export/properties.pyi

@@ -0,0 +1,68 @@
+from bpy.types import PropertyGroup, Object, Action
+
+from ...shared.types import BpyCollectionProperty, TransformMixin, ExportSpaceMixin, PsxBoneExportMixin, TransformSourceMixin
+
+class PsaExportSequenceMixin(PropertyGroup):
+    name: str
+    is_selected: bool
+    frame_start: int
+    frame_end: int
+    group: str
+    action_name: str
+    armature_object_name: str
+    marker_index: int
+    is_pose_marker: bool
+
+    @property
+    def action(self) -> Action | None: ...
+
+    @property
+    def armature_object(self) -> Object | None: ...
+
+    @property
+    def is_reversed(self) -> bool: ...
+
+
+class PSA_PG_export_sequence(PsaExportSequenceMixin):
+    """Concrete type for PSA export sequences."""
+    pass
+
+
+class PsaExportMixin(PropertyGroup, TransformMixin, ExportSpaceMixin, PsxBoneExportMixin, TransformSourceMixin):
+    sequence_source: str
+    nla_track: str
+    nla_track_index: int
+    fps_source: str
+    fps_custom: float
+    compression_ratio_source: str
+    compression_ratio_custom: float
+    action_list: BpyCollectionProperty[PSA_PG_export_sequence]
+    action_list_index: int
+    marker_list: BpyCollectionProperty[PSA_PG_export_sequence]
+    marker_list_index: int
+    nla_strip_list: BpyCollectionProperty[PSA_PG_export_sequence]
+    nla_strip_list_index: int
+    active_action_list: BpyCollectionProperty[PSA_PG_export_sequence]
+    active_action_list_index: int
+    sequence_name_prefix: str
+    sequence_name_suffix: str
+    sequence_filter_name: str
+    sequence_use_filter_invert: bool
+    sequence_filter_asset: bool
+    sequence_filter_pose_marker: bool
+    sequence_use_filter_sort_reverse: bool
+    sequence_filter_reversed: bool
+    sampling_mode: str
+    group_source: str
+    group_custom: str
+
+
+class PSA_PG_export(PsaExportMixin):
+    pass
+
+
+def get_sequences_from_name_and_frame_range(name: str, frame_start: int, frame_end: int):
+    pass
+
+def filter_sequences(pg: PsaExportMixin, sequences) -> list[int]:
+    pass

io_scene_psk_psa/psa/export/ui.py

@@ -2,7 +2,7 @@ from typing import cast as typing_cast
 
 from bpy.types import UIList
 
-from .properties import PSA_PG_export_action_list_item, filter_sequences
+from .properties import PsaExportSequenceMixin, filter_sequences
 
 
 class PSA_UL_export_sequences(UIList):
@@ -14,7 +14,7 @@ class PSA_UL_export_sequences(UIList):
         self.use_filter_show = True
 
     def draw_item(self, context, layout, data, item, icon, active_data, active_propname, index):
-        item = typing_cast(PSA_PG_export_action_list_item, item)
+        item = typing_cast(PsaExportSequenceMixin, item)
 
         is_pose_marker = hasattr(item, 'is_pose_marker') and item.is_pose_marker
         layout.prop(item, 'is_selected', icon_only=True, text=item.name)
@@ -24,9 +24,9 @@ class PSA_UL_export_sequences(UIList):
         row = layout.row(align=True)
         row.alignment = 'RIGHT'
 
-        row.label(text=str(abs(item.frame_end - item.frame_start) + 1), icon='FRAME_PREV' if item.frame_end < item.frame_start else 'KEYFRAME')
+        row.label(text=str(abs(item.frame_end - item.frame_start) + 1), icon='FRAME_PREV' if item.is_reversed else 'KEYFRAME')
 
-        if hasattr(item, 'armature_object') and item.armature_object is not None:
+        if item.armature_object is not None:
             row.label(text=item.armature_object.name, icon='ARMATURE_DATA')
 
         # row.label(text=item.action.name, icon='PMARKER' if is_pose_marker else 'ACTION_DATA')

io_scene_psk_psa/psa/file_handlers.py

@@ -0,0 +1,24 @@
+from bpy.types import Context
+from bpy.types import FileHandler
+
+from .import_.operators import PSA_OT_import_drag_and_drop
+from .export.operators import PSA_OT_export_collection
+
+class PSA_FH_file_handler(FileHandler):
+    bl_idname = 'PSA_FH_file_handler'
+    bl_label = 'Unreal PSA'
+    bl_import_operator = PSA_OT_import_drag_and_drop.bl_idname
+    bl_export_operator = PSA_OT_export_collection.bl_idname
+    bl_file_extensions = '.psa'
+
+    @classmethod
+    def poll_drop(cls, context: Context) -> bool:
+        return context.area is not None and context.area.type == 'VIEW_3D'
+
+
+_classes = (
+    PSA_FH_file_handler,
+)
+
+from bpy.utils import register_classes_factory
+register, unregister = register_classes_factory(_classes)

io_scene_psk_psa/psa/import_/operators.py

@@ -3,7 +3,7 @@ from pathlib import Path
 from typing import Iterable
 
 from bpy.props import CollectionProperty, StringProperty
-from bpy.types import Context, Event, FileHandler, Object, Operator, OperatorFileListElement
+from bpy.types import Context, Event, Object, Operator, OperatorFileListElement
 from bpy_extras.io_utils import ImportHelper
 
 from .properties import PsaImportMixin, get_visible_sequences
@@ -110,7 +110,7 @@ def load_psa_file(context, filepath: str):
     try:
         # Read the file and populate the action list.
         p = os.path.abspath(filepath)
-        psa_reader = PsaReader(p)
+        psa_reader = PsaReader.from_path(p)
         for sequence in psa_reader.sequences.values():
             item = pg.sequence_list.add()
             item.action_name = sequence.name.decode('windows-1252')
@@ -142,7 +142,7 @@ class PSA_OT_import_drag_and_drop(Operator, PsaImportMixin):
 
         for file in self.files:
             psa_path = str(os.path.join(self.directory, file.name))
-            psa_reader = PsaReader(psa_path)
+            psa_reader = PsaReader.from_path(psa_path)
             sequence_names = list(psa_reader.sequences.keys())
             options = psa_import_options_from_property_group(self, sequence_names)
 
@@ -188,6 +188,7 @@ def psa_import_options_from_property_group(pg: PsaImportMixin, sequence_names: I
     options.should_overwrite = pg.should_overwrite
     options.should_write_metadata = pg.should_write_metadata
     options.should_write_keyframes = pg.should_write_keyframes
+    options.should_write_scale_keys = pg.should_write_scale_keys
     options.should_convert_to_samples = pg.should_convert_to_samples
     options.bone_mapping = BoneMapping(
         is_case_sensitive=pg.bone_mapping_is_case_sensitive,
@@ -215,7 +216,7 @@ def _import_psa(context,
             except Exception as e:
                 warnings.append(f'Failed to read PSA config file: {e}')
 
-    psa_reader = PsaReader(filepath)
+    psa_reader = PsaReader.from_path(filepath)
 
     result = import_psa(context, psa_reader, armature_object, options)
     result.warnings.extend(warnings)
@@ -242,7 +243,7 @@ class PSA_OT_import_all(Operator, PsaImportMixin):
 
     def execute(self, context):
         sequence_names = []
-        with PsaReader(self.filepath) as psa_reader:
+        with PsaReader.from_path(self.filepath) as psa_reader:
             sequence_names.extend(psa_reader.sequences.keys())
 
         options = PsaImportOptions(
@@ -376,6 +377,7 @@ class PSA_OT_import(Operator, ImportHelper, PsaImportMixin):
             col.use_property_decorate = False
             col.prop(self, 'should_write_keyframes')
             col.prop(self, 'should_write_metadata')
+            col.prop(self, 'should_write_scale_keys')
 
             if self.should_write_keyframes:
                 col = col.column(heading='Keyframes')
@@ -426,6 +428,7 @@ def draw_psa_import_options_no_panels(layout, pg: PsaImportMixin):
     col.use_property_decorate = False
     col.prop(pg, 'should_write_keyframes')
     col.prop(pg, 'should_write_metadata')
+    col.prop(pg, 'should_write_scale_keys')
 
     if pg.should_write_keyframes:
         col = col.column(heading='Keyframes')
@@ -452,18 +455,6 @@ def draw_psa_import_options_no_panels(layout, pg: PsaImportMixin):
     col.prop(pg, 'should_use_config_file')
 
 
-class PSA_FH_import(FileHandler):  # TODO: rename and add handling for PSA export.
-    bl_idname = 'PSA_FH_import'
-    bl_label = 'File handler for Unreal PSA import'
-    bl_import_operator = PSA_OT_import_drag_and_drop.bl_idname
-    # bl_export_operator = 'psa_export.export'
-    bl_file_extensions = '.psa'
-
-    @classmethod
-    def poll_drop(cls, context: Context) -> bool:
-        return context.area is not None and context.area.type == 'VIEW_3D'
-
-
 _classes = (
     PSA_OT_import_sequences_select_all,
     PSA_OT_import_sequences_deselect_all,
@@ -471,7 +462,6 @@ _classes = (
     PSA_OT_import,
     PSA_OT_import_all,
     PSA_OT_import_drag_and_drop,
-    PSA_FH_import,
 )
 
 from bpy.utils import register_classes_factory

io_scene_psk_psa/psa/import_/properties.py

@@ -1,6 +1,5 @@
 import re
 from fnmatch import fnmatch
-from typing import List
 
 from bpy.props import (
     BoolProperty,
@@ -67,6 +66,7 @@ class PsaImportMixin:
     should_write_metadata: BoolProperty(default=True, name='Metadata', options=set(),
                                         description='Additional data will be written to the custom properties of the '
                                                     'Action (e.g., frame rate)')
+    should_write_scale_keys: BoolProperty(default=True, name='Scale Keys', options=set())
     sequence_filter_name: StringProperty(default='', options={'TEXTEDIT_UPDATE'})
     sequence_filter_is_selected: BoolProperty(default=False, options=set(), name='Only Show Selected',
                                               description='Only show selected sequences')
@@ -133,7 +133,7 @@ class PSA_PG_import(PropertyGroup):
     select_text: PointerProperty(type=Text)
 
 
-def filter_sequences(pg: PSA_PG_import, sequences) -> List[int]:
+def filter_sequences(pg: PSA_PG_import, sequences) -> list[int]:
     bitflag_filter_item = 1 << 30
     flt_flags = [bitflag_filter_item] * len(sequences)
 
@@ -167,7 +167,7 @@ def filter_sequences(pg: PSA_PG_import, sequences) -> List[int]:
     return flt_flags
 
 
-def get_visible_sequences(pg: PSA_PG_import, sequences) -> List[PSA_PG_import_action_list_item]:
+def get_visible_sequences(pg: PSA_PG_import, sequences) -> list[PSA_PG_import_action_list_item]:
     bitflag_filter_item = 1 << 30
     visible_sequences = []
     for i, flag in enumerate(filter_sequences(pg, sequences)):

io_scene_psk_psa/psa/import_/properties.pyi

@@ -0,0 +1,60 @@
+from bpy.types import PropertyGroup, Text
+
+from ...shared.types import BpyCollectionProperty
+
+
+class PSA_PG_import_action_list_item:
+    action_name: str
+    is_selected: bool
+
+
+class PSA_PG_bone:
+    bone_name: str
+
+
+class PSA_PG_data(PropertyGroup):
+    bones: BpyCollectionProperty[PSA_PG_bone]
+    sequence_count: int
+
+class PsaImportMixin:
+    should_use_fake_user: bool
+    should_use_config_file: bool
+    should_stash: bool
+    should_use_action_name_prefix: bool
+    action_name_prefix: str
+    should_overwrite: bool
+    should_write_keyframes: bool
+    should_write_metadata: bool
+    should_write_scale_keys: bool
+    sequence_filter_name: str
+    sequence_filter_is_selected: bool
+    sequence_use_filter_invert: bool
+    sequence_use_filter_regex: bool
+    should_convert_to_samples: bool
+    bone_mapping_is_case_sensitive: bool
+    bone_mapping_should_ignore_trailing_whitespace: bool
+    fps_source: str
+    fps_custom: float
+    compression_ratio_source: str
+    compression_ratio_custom: float
+    translation_scale: float
+    
+class PSA_PG_import:
+    psa_error: str
+    psa: PSA_PG_data
+    sequence_list: BpyCollectionProperty[PSA_PG_import_action_list_item]
+    sequence_list_index: int
+    sequence_filter_name: str
+    sequence_filter_is_selected: bool
+    sequence_use_filter_invert: bool
+    sequence_use_filter_regex: bool
+    select_text: Text | None
+
+
+
+def filter_sequences(pg: PSA_PG_import, sequences) -> list[int]:
+    pass
+
+
+def get_visible_sequences(pg: PSA_PG_import, sequences) -> list[PSA_PG_import_action_list_item]:
+    pass

io_scene_psk_psa/psa/import_/ui.py

@@ -22,9 +22,9 @@ class PSA_UL_sequences_mixin(UIList):
         sub_row.prop(pg, 'sequence_use_filter_regex', text='', icon='SORTBYEXT')
         sub_row.prop(pg, 'sequence_filter_is_selected', text='', icon='CHECKBOX_HLT')
 
-    def filter_items(self, context, data, property_):
+    def filter_items(self, context, data, property):
         pg = getattr(context.scene, 'psa_import')
-        sequences = getattr(data, property_)
+        sequences = getattr(data, property)
         flt_flags = filter_sequences(pg, sequences)
         flt_neworder = bpy.types.UI_UL_list.sort_items_by_name(sequences, 'action_name')
         return flt_flags, flt_neworder

io_scene_psk_psa/psa/importer.py

@@ -1,4 +1,4 @@
-from typing import Sequence, Iterable, List, Optional, cast as typing_cast
+from typing import Sequence, Iterable, cast as typing_cast
 
 import bpy
 import numpy as np
@@ -7,6 +7,8 @@ from bpy.types import Armature, Context, FCurve, Object, Bone, PoseBone
 from mathutils import Vector, Quaternion
 from bpy_extras import anim_utils
 
+from ..shared.types import PSX_PG_action_export
+
 from .config import PsaConfig, REMOVE_TRACK_LOCATION, REMOVE_TRACK_ROTATION
 from psk_psa_py.psa.reader import PsaReader
 from psk_psa_py.shared.data import PsxBone
@@ -30,7 +32,7 @@ class PsaImportOptions(object):
                  fps_custom: float = 30.0,
                  fps_source: str = 'SEQUENCE',
                  psa_config: PsaConfig = PsaConfig(),
-                 sequence_names: Optional[List[str]] = None,
+                 sequence_names: list[str] | None = None,
                  should_convert_to_samples: bool = False,
                  should_overwrite: bool = False,
                  should_stash: bool = False,
@@ -38,6 +40,7 @@ class PsaImportOptions(object):
                  should_use_fake_user: bool = False,
                  should_write_keyframes: bool = True,
                  should_write_metadata: bool = True,
+                 should_write_scale_keys: bool = True,
                  translation_scale: float = 1.0
                  ):
         self.action_name_prefix = action_name_prefix
@@ -53,25 +56,26 @@ class PsaImportOptions(object):
         self.should_use_fake_user = should_use_fake_user
         self.should_write_keyframes = should_write_keyframes
         self.should_write_metadata = should_write_metadata
+        self.should_write_scale_keys = should_write_scale_keys
         self.translation_scale = translation_scale
 
 
 class ImportBone(object):
     def __init__(self, psa_bone: PsxBone):
         self.psa_bone: PsxBone = psa_bone
-        self.parent: Optional[ImportBone] = None
-        self.armature_bone: Optional[Bone] = None
-        self.pose_bone: Optional[PoseBone] = None
+        self.parent: ImportBone | None = None
+        self.armature_bone: Bone | None = None
+        self.pose_bone: PoseBone | None = None
         self.original_location: Vector = Vector()
         self.original_rotation: Quaternion = Quaternion()
         self.post_rotation: Quaternion = Quaternion()
-        self.fcurves: List[FCurve] = []
+        self.fcurves: list[FCurve] = []
 
 
 def _calculate_fcurve_data(import_bone: ImportBone, key_data: Sequence[float]):
     # Convert world-space transforms to local-space transforms.
     key_rotation = Quaternion(key_data[0:4])
-    key_location = Vector(key_data[4:])
+    key_location = Vector(key_data[4:7])
     q = import_bone.post_rotation.copy()
     q.rotate(import_bone.original_rotation)
     rotation = q
@@ -83,15 +87,16 @@ def _calculate_fcurve_data(import_bone: ImportBone, key_data: Sequence[float]):
     rotation.rotate(q.conjugated())
     location = key_location - import_bone.original_location
     location.rotate(import_bone.post_rotation.conjugated())
-    return rotation.w, rotation.x, rotation.y, rotation.z, location.x, location.y, location.z
+    scale = Vector(key_data[7:10])
+    return rotation.w, rotation.x, rotation.y, rotation.z, location.x, location.y, location.z, scale.x, scale.y, scale.z
 
 
 class PsaImportResult:
     def __init__(self):
-        self.warnings: List[str] = []
+        self.warnings: list[str] = []
 
 
-def _get_armature_bone_index_for_psa_bone(psa_bone_name: str, armature_bone_names: List[str], bone_mapping: BoneMapping) -> Optional[int]:
+def _get_armature_bone_index_for_psa_bone(psa_bone_name: str, armature_bone_names: list[str], bone_mapping: BoneMapping) -> int | None:
     """
     @param psa_bone_name: The name of the PSA bone.
     @param armature_bone_names: The names of the bones in the armature.
@@ -167,6 +172,34 @@ def _resample_sequence_data_matrix(sequence_data_matrix: np.ndarray, frame_step:
     return resampled_sequence_data_matrix
 
 
+def _read_sequence_data_matrix(psa_reader: PsaReader, sequence_name: str) -> np.ndarray:
+    """
+    Reads and returns the data matrix for the given sequence.
+    The order of the data in the third axis is Qw, Qx, Qy, Qz, Lx, Ly, Lz, Sx, Sy, Sz
+    
+    @param sequence_name: The name of the sequence.
+    @return: An FxBx10 matrix where F is the number of frames, B is the number of bones.
+    """
+    sequence = psa_reader.sequences[sequence_name]
+    keys = psa_reader.read_sequence_keys(sequence_name)
+    bone_count = len(psa_reader.bones)
+    matrix_size = sequence.frame_count, bone_count, 10
+    matrix = np.ones(matrix_size)
+    keys_iter = iter(keys)
+    # Populate rotation and location data.
+    for frame_index in range(sequence.frame_count):
+        for bone_index in range(bone_count):
+            matrix[frame_index, bone_index, :7] = list(next(keys_iter).data)
+    # Populate scale data, if it exists.
+    scale_keys = psa_reader.read_sequence_scale_keys(sequence_name)
+    if len(scale_keys) > 0:
+        scale_keys_iter = iter(scale_keys)
+        for frame_index in range(sequence.frame_count):
+            for bone_index in range(bone_count):
+                matrix[frame_index, bone_index, 7:] = list(next(scale_keys_iter).data)
+    return matrix
+
+
 def import_psa(context: Context, psa_reader: PsaReader, armature_object: Object, options: PsaImportOptions) -> PsaImportResult:
 
     assert context.window_manager
@@ -309,8 +342,10 @@ def import_psa(context: Context, psa_reader: PsaReader, armature_object: Object,
                 pose_bone = import_bone.pose_bone
                 rotation_data_path = pose_bone.path_from_id('rotation_quaternion')
                 location_data_path = pose_bone.path_from_id('location')
+                scale_data_path = pose_bone.path_from_id('scale')
                 add_rotation_fcurves = (bone_track_flags & REMOVE_TRACK_ROTATION) == 0
                 add_location_fcurves = (bone_track_flags & REMOVE_TRACK_LOCATION) == 0
+                add_scale_fcurves = psa_reader.has_scale_keys and options.should_write_scale_keys
                 import_bone.fcurves = [
                     channelbag.fcurves.ensure(rotation_data_path, index=0, group_name=pose_bone.name) if add_rotation_fcurves else None,  # Qw
                     channelbag.fcurves.ensure(rotation_data_path, index=1, group_name=pose_bone.name) if add_rotation_fcurves else None,  # Qx
@@ -319,14 +354,17 @@ def import_psa(context: Context, psa_reader: PsaReader, armature_object: Object,
                     channelbag.fcurves.ensure(location_data_path, index=0, group_name=pose_bone.name) if add_location_fcurves else None,  # Lx
                     channelbag.fcurves.ensure(location_data_path, index=1, group_name=pose_bone.name) if add_location_fcurves else None,  # Ly
                     channelbag.fcurves.ensure(location_data_path, index=2, group_name=pose_bone.name) if add_location_fcurves else None,  # Lz
+                    channelbag.fcurves.ensure(scale_data_path,    index=0, group_name=pose_bone.name) if add_scale_fcurves    else None,  # Sx
+                    channelbag.fcurves.ensure(scale_data_path,    index=1, group_name=pose_bone.name) if add_scale_fcurves    else None,  # Sy
+                    channelbag.fcurves.ensure(scale_data_path,    index=2, group_name=pose_bone.name) if add_scale_fcurves    else None,  # Sz
                 ]
 
             # Read the sequence data matrix from the PSA.
-            sequence_data_matrix = psa_reader.read_sequence_data_matrix(sequence_name)
+            sequence_data_matrix = _read_sequence_data_matrix(psa_reader, sequence_name)
 
             if options.translation_scale != 1.0:
                 # Scale the translation data.
-                sequence_data_matrix[:, :, 4:] *= options.translation_scale
+                sequence_data_matrix[:, :, 4:7] *= options.translation_scale
 
             # Convert the sequence's data from world-space to local-space.
             for bone_index, import_bone in enumerate(import_bones):
@@ -364,12 +402,13 @@ def import_psa(context: Context, psa_reader: PsaReader, armature_object: Object,
 
             if options.should_convert_to_samples:
                 # Bake the curve to samples.
-                for fcurve in action.fcurves:
+                for fcurve in channelbag.fcurves:
                     fcurve.convert_to_samples(start=0, end=sequence.frame_count)
 
         # Write meta-data.
         if options.should_write_metadata:
-            action.psa_export.fps = target_fps
+            pg = typing_cast(PSX_PG_action_export, getattr(action, 'psa_export'))
+            pg.fps = target_fps
 
         action.use_fake_user = options.should_use_fake_user
 

io_scene_psk_psa/psk/builder.py

@@ -1,137 +1,84 @@
 import bmesh
 import bpy
 import numpy as np
-from bpy.types import Armature, Collection, Context, Depsgraph, Object, ArmatureModifier, Mesh
-from mathutils import Matrix
-from typing import Dict, Iterable, List, Optional, Set, cast as typing_cast
-from psk_psa_py.shared.data import Vector3
+from bpy.types import Armature, Context, Object, Mesh
+from mathutils import Matrix, Quaternion
+from typing import Iterable, cast as typing_cast
+from psk_psa_py.shared.data import PsxBone, Vector3
 from psk_psa_py.psk.data import Psk
 from .properties import triangle_type_and_bit_flags_to_poly_flags
-from ..shared.dfs import DfsObject, dfs_collection_objects, dfs_view_layer_objects
 from ..shared.helpers import (
+    ObjectNode,
+    ObjectTree,
+    PskInputObjects,
     PsxBoneCollection,
+    convert_bpy_quaternion_to_psx_quaternion,
     convert_string_to_cp1252_bytes,
     create_psx_bones,
-    get_armatures_for_mesh_objects,
+    get_armature_for_mesh_object,
     get_coordinate_system_transform,
+    get_materials_for_mesh_objects,
 )
 
 
-class PskInputObjects(object):
-    def __init__(self):
-        self.mesh_dfs_objects: List[DfsObject] = []
-        self.armature_objects: Set[Object] = set()
-
-
 class PskBuildOptions(object):
     def __init__(self):
         self.bone_filter_mode = 'ALL'
-        self.bone_collection_indices: List[PsxBoneCollection] = []
+        self.bone_collection_indices: list[PsxBoneCollection] = []
         self.object_eval_state = 'EVALUATED'
         self.material_order_mode = 'AUTOMATIC'
-        self.material_name_list: List[str] = []
+        self.material_name_list: list[str] = []
         self.scale = 1.0
         self.export_space = 'WORLD'
         self.forward_axis = 'X'
         self.up_axis = 'Z'
-        self.root_bone_name = 'ROOT'
-
-
-def get_materials_for_mesh_objects(depsgraph: Depsgraph, mesh_objects: Iterable[Object]):
-    yielded_materials = set()
-    for mesh_object in mesh_objects:
-        evaluated_mesh_object = mesh_object.evaluated_get(depsgraph)
-        for i, material_slot in enumerate(evaluated_mesh_object.material_slots):
-            material = material_slot.material
-            if material is None:
-                raise RuntimeError(f'Material slots cannot be empty. ({mesh_object.name}, index {i})')
-            if material not in yielded_materials:
-                yielded_materials.add(material)
-                yield material
-
-
-def get_mesh_objects_for_collection(collection: Collection) -> Iterable[DfsObject]:
-    return filter(lambda x: x.obj.type == 'MESH', dfs_collection_objects(collection))
-
-
-def get_mesh_objects_for_context(context: Context) -> Iterable[DfsObject]:
-    if context.view_layer is None:
-        return
-    for dfs_object in dfs_view_layer_objects(context.view_layer):
-        if dfs_object.obj.type == 'MESH' and dfs_object.is_selected:
-            yield dfs_object
-
-
-def get_armature_for_mesh_object(mesh_object: Object) -> Optional[Object]:
-    if mesh_object.type != 'MESH':
-        return None
-    # Get the first armature modifier with a non-empty armature object.
-    for modifier in filter(lambda x: x.type == 'ARMATURE', mesh_object.modifiers):
-            armature_modifier = typing_cast(ArmatureModifier, modifier)
-            if armature_modifier.object is not None:
-                return armature_modifier.object
-    return None
-
-
-def _get_psk_input_objects(mesh_dfs_objects: Iterable[DfsObject]) -> PskInputObjects:
-    mesh_dfs_objects = list(mesh_dfs_objects)
-    if len(mesh_dfs_objects) == 0:
-        raise RuntimeError('At least one mesh must be selected')
-    input_objects = PskInputObjects()
-    input_objects.mesh_dfs_objects = mesh_dfs_objects
-    input_objects.armature_objects |= set(get_armatures_for_mesh_objects(map(lambda x: x.obj, mesh_dfs_objects)))
-    return input_objects
-
-
-def get_psk_input_objects_for_context(context: Context) -> PskInputObjects:
-    mesh_objects = list(get_mesh_objects_for_context(context))
-    return _get_psk_input_objects(mesh_objects)
-
-
-def get_psk_input_objects_for_collection(collection: Collection) -> PskInputObjects:
-    mesh_objects = get_mesh_objects_for_collection(collection)
-    return _get_psk_input_objects(mesh_objects)
 
 
 class PskBuildResult(object):
     def __init__(self, psk: Psk, warnings: list[str]):
         self.psk: Psk = psk
-        self.warnings: List[str] = warnings
+        self.warnings: list[str] = warnings
 
 
-def _get_mesh_export_space_matrix(armature_object: Optional[Object], export_space: str) -> Matrix:
-    if armature_object is None:
+def _get_mesh_export_space_matrix(node: ObjectNode | None, export_space: str) -> Matrix:
+    if node is None:
         return Matrix.Identity(4)
     
+    armature_object = node.object
+    root_armature_object = node.root.object
+
     def get_object_space_matrix(obj: Object) -> Matrix:
         translation, rotation, _ = obj.matrix_world.decompose()
         # We neutralize the scale here because the scale is already applied to the mesh objects implicitly.
         return Matrix.Translation(translation) @ rotation.to_matrix().to_4x4()
 
+    armature_space_matrix = get_object_space_matrix(armature_object)
+    root_armature_space_matrix = get_object_space_matrix(root_armature_object)
+    relative_matrix = root_armature_space_matrix @ armature_space_matrix.inverted()
+
     match export_space:
         case 'WORLD':
             return Matrix.Identity(4)
         case 'ARMATURE':
-            return get_object_space_matrix(armature_object).inverted()
+            return (armature_space_matrix @ relative_matrix).inverted()
         case 'ROOT':
-            armature_data = typing_cast(Armature, armature_object.data)
-            armature_space_matrix = get_object_space_matrix(armature_object) @ armature_data.bones[0].matrix_local
-            return armature_space_matrix.inverted()
+            root_armature_data = typing_cast(Armature, root_armature_object.data)
+            if len(root_armature_data.bones) == 0:
+                raise RuntimeError(f'Armature {root_armature_data.name} has no bones')
+            return (armature_space_matrix @ relative_matrix @ root_armature_data.bones[0].matrix_local).inverted()
         case _:
             assert False, f'Invalid export space: {export_space}'
 
 
-def _get_material_name_indices(obj: Object, material_names: List[str]) -> Iterable[int]:
+def _get_material_name_indices(obj: Object, material_names: list[str]) -> Iterable[int]:
     """
     Returns the index of the material in the list of material names.
-    If the material is not found, the index 0 is returned.
+    If the material is not found or the slot is empty, the index of 'None' is returned.
     """
     for material_slot in obj.material_slots:
-        if material_slot.material is None:
-            yield 0
-        else:
         try:
-                yield material_names.index(material_slot.material.name)
+            material_name = material_slot.material.name if material_slot.material is not None else 'None'
+            yield material_names.index(material_name)
         except ValueError:
             yield 0
 
@@ -141,6 +88,7 @@ def build_psk(context: Context, input_objects: PskInputObjects, options: PskBuil
     assert context.window_manager
 
     armature_objects = list(input_objects.armature_objects)
+    armature_object_tree = ObjectTree(input_objects.armature_objects)    
 
     warnings: list[str] = []
     psk = Psk()
@@ -151,23 +99,49 @@ def build_psk(context: Context, input_objects: PskInputObjects, options: PskBuil
         forward_axis=options.forward_axis,
         up_axis=options.up_axis,
         scale=options.scale,
-        root_bone_name=options.root_bone_name,
         bone_filter_mode=options.bone_filter_mode,
         bone_collection_indices=options.bone_collection_indices
     )
 
-    psk.bones = [psx_bone for psx_bone, _ in psx_bone_create_result.bones]
+    psk.bones = [bone.psx_bone for bone in psx_bone_create_result.bones]
+
+    if len(psk.bones) == 0:
+        # Add a default root bone if there are no bones to export.
+        # This is necessary because Unreal Engine requires at least one bone in the PSK file.
+        psx_bone = PsxBone()
+        psx_bone.name = b'ROOT'
+        psx_bone.rotation = convert_bpy_quaternion_to_psx_quaternion(Quaternion())
+        psk.bones.append(psx_bone)
 
     # Materials
+    mesh_objects = [dfs_object.obj for dfs_object in input_objects.mesh_dfs_objects]
+    
     match options.material_order_mode:
         case 'AUTOMATIC':
-            mesh_objects = [dfs_object.obj for dfs_object in input_objects.mesh_dfs_objects]
             materials = list(get_materials_for_mesh_objects(context.evaluated_depsgraph_get(), mesh_objects))
         case 'MANUAL':
             # The material name list may contain materials that are not on the mesh objects.
             # Therefore, we can take the material_name_list as gospel and simply use it as a lookup table.
             # If a look-up fails, replace it with an empty material.
             materials = [bpy.data.materials.get(x, None) for x in options.material_name_list]
+            
+            # Check if any mesh needs a None material (has no slots or empty slots)
+            needs_none_material = False
+            for mesh_object in mesh_objects:
+                evaluated_mesh_object = mesh_object.evaluated_get(context.evaluated_depsgraph_get())
+                if len(evaluated_mesh_object.material_slots) == 0:
+                    needs_none_material = True
+                    break
+                for material_slot in evaluated_mesh_object.material_slots:
+                    if material_slot.material is None:
+                        needs_none_material = True
+                        break
+                if needs_none_material:
+                    break
+            
+            # Append None at the end if needed and not already present
+            if needs_none_material and None not in materials:
+                materials.append(None)
         case _:
             assert False, f'Invalid material order mode: {options.material_order_mode}'
 
@@ -180,11 +154,7 @@ def build_psk(context: Context, input_objects: PskInputObjects, options: PskBuil
                                                                                 material.psk.mesh_triangle_bit_flags)
         psk.materials.append(psk_material)
 
-    # TODO: This wasn't left in a good state. We should detect if we need to add a "default" material.
-    #  This can be done by checking if there is an empty material slot on any of the mesh objects, or if there are
-    #  no material slots on any of the mesh objects.
-    #  If so, it should be added to the end of the list of materials, and its index should mapped to a None value in the
-    #  material indices list.
+    # Ensure at least one material exists
     if len(psk.materials) == 0:
         # Add a default material if no materials are present.
         psk_material = Psk.Material()
@@ -192,30 +162,32 @@ def build_psk(context: Context, input_objects: PskInputObjects, options: PskBuil
         psk.materials.append(psk_material)
 
     context.window_manager.progress_begin(0, len(input_objects.mesh_dfs_objects))
-
     coordinate_system_matrix = get_coordinate_system_transform(options.forward_axis, options.up_axis)
+    root_armature_object = next(iter(armature_object_tree), None)
 
     # Calculate the export spaces for the armature objects.
     # This is used later to transform the mesh object geometry into the export space.
-    armature_mesh_export_space_matrices: Dict[Optional[Object], Matrix] = {None: Matrix.Identity(4)}
+    armature_mesh_export_space_matrices: dict[Object | None, Matrix] = {None: Matrix.Identity(4)}
+
     if options.export_space == 'ARMATURE':
-        # For meshes without an armature modifier, we need to set the export space to the armature object.
-        armature_mesh_export_space_matrices[None] = _get_mesh_export_space_matrix(next(iter(input_objects.armature_objects), None), options.export_space)
-    for armature_object in armature_objects:
-        armature_mesh_export_space_matrices[armature_object] = _get_mesh_export_space_matrix(armature_object, options.export_space)
+        # For meshes without an armature modifier, we need to set the export space to the first armature object.
+        armature_mesh_export_space_matrices[None] = _get_mesh_export_space_matrix(root_armature_object, options.export_space)
     
-    scale_matrix = Matrix.Scale(options.scale, 4)
-
-    original_armature_object_pose_positions = {a: a.data.pose_position for a in armature_objects}
+    # TODO: also handle the case of multiple roots; dont' just assume we have one!
+    for armature_node in iter(armature_object_tree):
+        armature_mesh_export_space_matrices[armature_node.object] = _get_mesh_export_space_matrix(armature_node, options.export_space)
     
     # Temporarily force the armature into the rest position.
-    # We will undo this later.
+    # The original pose position setting will be restored at the end.
+    original_armature_object_pose_positions = {a: a.data.pose_position for a in armature_objects}
     for armature_object in armature_objects:
         armature_data = typing_cast(Armature, armature_object.data)
         armature_data.pose_position = 'REST'
 
     material_names = [m.name if m is not None else 'None' for m in materials]
 
+    scale_matrix = Matrix.Scale(options.scale, 4)
+
     for object_index, input_mesh_object in enumerate(input_objects.mesh_dfs_objects):
         obj, matrix_world = input_mesh_object.obj, input_mesh_object.matrix_world
         armature_object = get_armature_for_mesh_object(obj)
@@ -225,8 +197,12 @@ def build_psk(context: Context, input_objects: PskInputObjects, options: PskBuil
         material_indices = list(_get_material_name_indices(obj, material_names))
 
         if len(material_indices) == 0:
-            # Add a default material if no materials are present.
-            material_indices = [0]
+            # If the mesh has no material slots, map to the 'None' material index
+            try:
+                none_material_index = material_names.index('None')
+            except ValueError:
+                none_material_index = 0
+            material_indices = [none_material_index]
 
         # Store the reference to the evaluated object and data so that we can clean them up later.
         evaluated_mesh_object = None
@@ -286,7 +262,7 @@ def build_psk(context: Context, input_objects: PskInputObjects, options: PskBuil
             case _:
                 assert False, f'Invalid export space: {options.export_space}'
 
-        vertex_transform_matrix = scale_matrix @ coordinate_system_matrix @ mesh_export_space_matrix
+        vertex_transform_matrix = scale_matrix @ coordinate_system_matrix.inverted() @ mesh_export_space_matrix
         point_transform_matrix = vertex_transform_matrix @ mesh_object.matrix_world
 
         # Vertices
@@ -319,6 +295,7 @@ def build_psk(context: Context, input_objects: PskInputObjects, options: PskBuil
             for loop_index, loop in enumerate(mesh_data.loops):
                 wedges.append(Psk.Wedge(point_index=loop.vertex_index + vertex_offset, u=0.0, v=0.0))
 
+
         # Assign material indices to the wedges.
         for triangle in mesh_data.loop_triangles:
             for loop_index in triangle.loops:
@@ -341,18 +318,17 @@ def build_psk(context: Context, input_objects: PskInputObjects, options: PskBuil
         poly_groups, groups = mesh_data.calc_smooth_groups(use_bitflags=True)
         psk_face_start_index = len(psk.faces)
         for f in mesh_data.loop_triangles:
-            face = Psk.Face()
-            face.material_index = material_indices[f.material_index]
-            face.wedge_indices[0] = loop_wedge_indices[f.loops[2]]
-            face.wedge_indices[1] = loop_wedge_indices[f.loops[1]]
-            face.wedge_indices[2] = loop_wedge_indices[f.loops[0]]
-            face.smoothing_groups = poly_groups[f.polygon_index]
+            face = Psk.Face(
+                wedge_indices=(loop_wedge_indices[f.loops[2]], loop_wedge_indices[f.loops[1]], loop_wedge_indices[f.loops[0]]),
+                material_index=material_indices[f.material_index],
+                smoothing_groups=poly_groups[f.polygon_index],
+            )
             psk.faces.append(face)
 
         if should_flip_normals:
             # Invert the normals of the faces.
             for face in psk.faces[psk_face_start_index:]:
-                face.wedge_indices[0], face.wedge_indices[2] = face.wedge_indices[2], face.wedge_indices[0]
+                face.wedge_indices = (face.wedge_indices[2], face.wedge_indices[1], face.wedge_indices[0])
 
         # Weights
         if armature_object is not None:
@@ -363,7 +339,7 @@ def build_psk(context: Context, input_objects: PskInputObjects, options: PskBuil
 
             bone_names = psx_bone_create_result.armature_object_bone_names[armature_object]
             vertex_group_names = [x.name for x in mesh_object.vertex_groups]
-            vertex_group_bone_indices: Dict[int, int] = dict()
+            vertex_group_bone_indices: dict[int, int] = dict()
             for vertex_group_index, vertex_group_name in enumerate(vertex_group_names):
                 try:
                     vertex_group_bone_indices[vertex_group_index] = bone_names.index(vertex_group_name) + bone_index_offset

io_scene_psk_psa/psk/export/operators.py

@@ -1,22 +1,21 @@
 from pathlib import Path
-from typing import Iterable, List
+from typing import Iterable, cast as typing_cast
 
 import bpy
-from bpy.props import BoolProperty, StringProperty
+from bpy.props import StringProperty
 from bpy.types import Context, Depsgraph, Material, Object, Operator, Scene
 from bpy_extras.io_utils import ExportHelper
 
-from .properties import PskExportMixin
+from .properties import PSK_PG_export, PskExportMixin
 from ..builder import (
     PskBuildOptions,
     build_psk,
     get_materials_for_mesh_objects,
-    get_psk_input_objects_for_collection,
-    get_psk_input_objects_for_context,
 )
 from psk_psa_py.psk.writer import write_psk_to_path
-from ...shared.helpers import PsxBoneCollection, get_collection_export_operator_from_context, populate_bone_collection_list
+from ...shared.helpers import PsxBoneCollection, get_collection_export_operator_from_context, get_psk_input_objects_for_collection, populate_bone_collection_list, get_psk_input_objects_for_context
 from ...shared.ui import draw_bone_filter_mode
+from ...shared.operators import PSK_OT_bone_collection_list_populate, PSK_OT_bone_collection_list_select_all
 
 
 def populate_material_name_list(depsgraph: Depsgraph, mesh_objects: Iterable[Object], material_list):
@@ -30,55 +29,10 @@ def populate_material_name_list(depsgraph: Depsgraph, mesh_objects: Iterable[Obj
     material_list.clear()
     for index, material in enumerate(materials):
         m = material_list.add()
-        m.material_name = material.name
+        m.material_name = material.name if material is not None else 'None'
         m.index = index
 
 
-
-class PSK_OT_bone_collection_list_populate(Operator):
-    bl_idname = 'psk.bone_collection_list_populate'
-    bl_label = 'Populate Bone Collection List'
-    bl_description = 'Populate the bone collection list from the armature that will be used in this collection export'
-    bl_options = {'INTERNAL'}
-
-    def execute(self, context):
-        export_operator = get_collection_export_operator_from_context(context)
-        if export_operator is None:
-            self.report({'ERROR_INVALID_CONTEXT'}, 'No valid export operator found in context')
-            return {'CANCELLED'}
-        if context.collection is None:
-            self.report({'ERROR_INVALID_CONTEXT'}, 'No active collection')
-            return {'CANCELLED'}
-        try:
-            input_objects = get_psk_input_objects_for_collection(context.collection)
-        except RuntimeError as e:
-            self.report({'ERROR_INVALID_CONTEXT'}, str(e))
-            return {'CANCELLED'}
-        if not input_objects.armature_objects:
-            self.report({'ERROR_INVALID_CONTEXT'}, 'No armature modifiers found on mesh objects')
-            return {'CANCELLED'}
-        populate_bone_collection_list(export_operator.bone_collection_list, input_objects.armature_objects)
-        return {'FINISHED'}
-
-
-class PSK_OT_bone_collection_list_select_all(Operator):
-    bl_idname = 'psk.bone_collection_list_select_all'
-    bl_label = 'Select All'
-    bl_description = 'Select all bone collections'
-    bl_options = {'INTERNAL'}
-
-    is_selected: BoolProperty(default=True)
-
-    def execute(self, context):
-        export_operator = get_collection_export_operator_from_context(context)
-        if export_operator is None:
-            self.report({'ERROR_INVALID_CONTEXT'}, 'No valid export operator found in context')
-            return {'CANCELLED'}
-        for item in export_operator.bone_collection_list:
-            item.is_selected = self.is_selected
-        return {'FINISHED'}
-
-
 class PSK_OT_populate_material_name_list(Operator):
     bl_idname = 'psk.export_populate_material_name_list'
     bl_label = 'Populate Material Name List'
@@ -90,6 +44,7 @@ class PSK_OT_populate_material_name_list(Operator):
         if export_operator is None:
             self.report({'ERROR_INVALID_CONTEXT'}, 'No valid export operator found in context')
             return {'CANCELLED'}
+        export_operator = typing_cast(PskExportMixin, export_operator)
         depsgraph = context.evaluated_depsgraph_get()
         assert context.collection
         input_objects = get_psk_input_objects_for_collection(context.collection)
@@ -124,6 +79,7 @@ class PSK_OT_material_list_name_add(Operator):
         if export_operator is None:
             self.report({'ERROR_INVALID_CONTEXT'}, 'No valid export operator found in context')
             return {'CANCELLED'}
+        export_operator = typing_cast(PskExportMixin, export_operator)
         m = export_operator.material_name_list.add()
         m.material_name = self.name
         m.index = len(export_operator.material_name_list) - 1
@@ -139,11 +95,11 @@ class PSK_OT_material_list_move_up(Operator):
 
     @classmethod
     def poll(cls, context):
-        pg = getattr(context.scene, 'psk_export')
+        pg = typing_cast(PSK_PG_export, getattr(context.scene, 'psk_export'))
         return pg.material_name_list_index > 0
 
     def execute(self, context):
-        pg = getattr(context.scene, 'psk_export')
+        pg = typing_cast(PSK_PG_export, getattr(context.scene, 'psk_export'))
         pg.material_name_list.move(pg.material_name_list_index, pg.material_name_list_index - 1)
         pg.material_name_list_index -= 1
         return {'FINISHED'}
@@ -157,11 +113,11 @@ class PSK_OT_material_list_move_down(Operator):
 
     @classmethod
     def poll(cls, context):
-        pg = getattr(context.scene, 'psk_export')
+        pg = typing_cast(PSK_PG_export, getattr(context.scene, 'psk_export'))
         return pg.material_name_list_index < len(pg.material_name_list) - 1
 
     def execute(self, context):
-        pg = getattr(context.scene, 'psk_export')
+        pg = typing_cast(PSK_PG_export, getattr(context.scene, 'psk_export'))
         pg.material_name_list.move(pg.material_name_list_index, pg.material_name_list_index + 1)
         pg.material_name_list_index += 1
         return {'FINISHED'}
@@ -178,6 +134,7 @@ class PSK_OT_material_list_name_move_up(Operator):
         export_operator = get_collection_export_operator_from_context(context)
         if export_operator is None:
             return False
+        export_operator = typing_cast(PskExportMixin, export_operator)
         return export_operator.material_name_list_index > 0
 
     def execute(self, context):
@@ -185,6 +142,7 @@ class PSK_OT_material_list_name_move_up(Operator):
         if export_operator is None:
             self.report({'ERROR_INVALID_CONTEXT'}, 'No valid export operator found in context')
             return {'CANCELLED'}
+        export_operator = typing_cast(PskExportMixin, export_operator)
         export_operator.material_name_list.move(export_operator.material_name_list_index, export_operator.material_name_list_index - 1)
         export_operator.material_name_list_index -= 1
         return {'FINISHED'}
@@ -201,6 +159,7 @@ class PSK_OT_material_list_name_move_down(Operator):
         export_operator = get_collection_export_operator_from_context(context)
         if export_operator is None:
             return False
+        export_operator = typing_cast(PskExportMixin, export_operator)
         return export_operator.material_name_list_index < len(export_operator.material_name_list) - 1
 
     def execute(self, context):
@@ -208,24 +167,38 @@ class PSK_OT_material_list_name_move_down(Operator):
         if export_operator is None:
             self.report({'ERROR_INVALID_CONTEXT'}, 'No valid export operator found in context')
             return {'CANCELLED'}
+        export_operator = typing_cast(PskExportMixin, export_operator)
         export_operator.material_name_list.move(export_operator.material_name_list_index, export_operator.material_name_list_index + 1)
         export_operator.material_name_list_index += 1
         return {'FINISHED'}
 
 
-def get_sorted_materials_by_names(materials: Iterable[Material], material_names: List[str]) -> List[Material]:
+def get_sorted_materials_by_names(materials: Iterable[Material | None], material_names: list[str]) -> list[Material | None]:
     """
     Sorts the materials by the order of the material names list. Any materials not in the list will be appended to the
-    end of the list in the order they are found.
+    end of the list in the order they are found. None materials (representing empty material slots) are always
+    appended at the very end.
 
-    @param materials: A list of materials to sort
+    @param materials: A list of materials to sort (can include None)
     @param material_names: A list of material names to sort by
-    @return: A sorted list of materials
+    @return: A sorted list of materials (with None at the end if present)
     """
+    materials = list(materials)
+    has_none = None in materials
+    materials = [m for m in materials if m is not None]
+    
     materials_in_collection = [m for m in materials if m.name in material_names]
     materials_not_in_collection = [m for m in materials if m.name not in material_names]
     materials_in_collection = sorted(materials_in_collection, key=lambda x: material_names.index(x.name))
-    return materials_in_collection + materials_not_in_collection
+    
+    result: list[Material | None] = []
+    result.extend(materials_in_collection)
+    result.extend(materials_not_in_collection)
+    
+    if has_none:
+        result.append(None)
+    
+    return result
 
 
 def get_psk_build_options_from_property_group(scene: Scene, pg: PskExportMixin) -> PskBuildOptions:
@@ -234,7 +207,6 @@ def get_psk_build_options_from_property_group(scene: Scene, pg: PskExportMixin)
     options.export_space = pg.export_space
     options.bone_filter_mode = pg.bone_filter_mode
     options.bone_collection_indices = [PsxBoneCollection(x.armature_object_name, x.armature_data_name, x.index) for x in pg.bone_collection_list if x.is_selected]
-    options.root_bone_name = pg.root_bone_name
     options.material_order_mode = pg.material_order_mode
     options.material_name_list = [x.material_name for x in pg.material_name_list]
     
@@ -291,6 +263,9 @@ class PSK_OT_export_collection(Operator, ExportHelper, PskExportMixin):
                 self.report({'WARNING'}, f'PSK export successful with {len(result.warnings)} warnings')
             else:
                 self.report({'INFO'}, f'PSK export successful')
+        except IOError as e:
+            self.report({'ERROR'}, f'Failed to write PSK file ({filepath}): {e}')
+            return {'CANCELLED'}
         except RuntimeError as e:
             self.report({'ERROR_INVALID_CONTEXT'}, str(e))
             return {'CANCELLED'}
@@ -333,14 +308,6 @@ class PSK_OT_export_collection(Operator, ExportHelper, PskExportMixin):
                 op = col.operator(PSK_OT_bone_collection_list_select_all.bl_idname, text='', icon='CHECKBOX_DEHLT')
                 op.is_selected = False
 
-            advanced_bones_header, advanced_bones_panel = bones_panel.panel('Advanced', default_closed=True)
-            advanced_bones_header.label(text='Advanced')
-            if advanced_bones_panel:
-                flow = advanced_bones_panel.grid_flow(row_major=True)
-                flow.use_property_split = True
-                flow.use_property_decorate = False
-                flow.prop(self, 'root_bone_name')
-
         # Materials
         materials_header, materials_panel = layout.panel('Materials', default_closed=False)
         materials_header.label(text='Materials', icon='MATERIAL')
@@ -411,7 +378,7 @@ class PSK_OT_export(Operator, ExportHelper):
             self.report({'ERROR_INVALID_CONTEXT'}, str(e))
             return {'CANCELLED'}
 
-        pg = getattr(context.scene, 'psk_export')
+        pg = typing_cast(PSK_PG_export, getattr(context.scene, 'psk_export'))
 
         populate_bone_collection_list(pg.bone_collection_list, input_objects.armature_objects)
 
@@ -433,7 +400,7 @@ class PSK_OT_export(Operator, ExportHelper):
 
         assert layout
 
-        pg = getattr(context.scene, 'psk_export')
+        pg = typing_cast(PSK_PG_export, getattr(context.scene, 'psk_export'))
 
         # Mesh
         mesh_header, mesh_panel = layout.panel('Mesh', default_closed=False)
@@ -453,13 +420,6 @@ class PSK_OT_export(Operator, ExportHelper):
                 row = bones_panel.row()
                 rows = max(3, min(len(pg.bone_collection_list), 10))
                 row.template_list('PSX_UL_bone_collection_list', '', pg, 'bone_collection_list', pg, 'bone_collection_list_index', rows=rows)
-            bones_advanced_header, bones_advanced_panel = bones_panel.panel('Advanced', default_closed=True)
-            bones_advanced_header.label(text='Advanced')
-            if bones_advanced_panel:
-                flow = bones_advanced_panel.grid_flow(row_major=True)
-                flow.use_property_split = True
-                flow.use_property_decorate = False
-                flow.prop(pg, 'root_bone_name')
 
         # Materials
         materials_header, materials_panel = layout.panel('Materials', default_closed=False)
@@ -531,6 +491,9 @@ class PSK_OT_export(Operator, ExportHelper):
                 self.report({'WARNING'}, f'PSK export successful with {len(result.warnings)} warnings')
             else:
                 self.report({'INFO'}, f'PSK export successful')
+        except IOError as e:
+            self.report({'ERROR'}, f'Failed to write PSK file ({self.filepath}): {e}')
+            return {'CANCELLED'}
         except RuntimeError as e:
             self.report({'ERROR_INVALID_CONTEXT'}, str(e))
             return {'CANCELLED'}
@@ -543,8 +506,6 @@ _classes = (
     PSK_OT_material_list_move_down,
     PSK_OT_export,
     PSK_OT_export_collection,
-    PSK_OT_bone_collection_list_populate,
-    PSK_OT_bone_collection_list_select_all,
     PSK_OT_populate_material_name_list,
     PSK_OT_material_list_name_move_up,
     PSK_OT_material_list_name_move_down,

io_scene_psk_psa/psk/export/properties.py

@@ -3,12 +3,11 @@ from bpy.props import (
     CollectionProperty,
     EnumProperty,
     IntProperty,
-    PointerProperty,
     StringProperty,
 )
-from bpy.types import Material, PropertyGroup
+from bpy.types import PropertyGroup
 
-from ...shared.types import ExportSpaceMixin, TransformMixin, PsxBoneExportMixin
+from ...shared.types import ExportSpaceMixin, TransformMixin, PsxBoneExportMixin, TransformSourceMixin
 
 object_eval_state_items = (
     ('EVALUATED', 'Evaluated', 'Use data from fully evaluated object'),
@@ -20,22 +19,13 @@ material_order_mode_items = (
     ('MANUAL', 'Manual', 'Manually arrange the materials'),
 )
 
-transform_source_items = (
-    ('SCENE', 'Scene', 'Use the scene transform settings'),
-    ('CUSTOM', 'Custom', 'Use custom transform settings'),
-)
-
-class PSK_PG_material_list_item(PropertyGroup):
-    material: PointerProperty(type=Material)
-    index: IntProperty()
-
 
 class PSK_PG_material_name_list_item(PropertyGroup):
     material_name: StringProperty()
     index: IntProperty()
 
 
-class PskExportMixin(ExportSpaceMixin, TransformMixin, PsxBoneExportMixin):
+class PskExportMixin(ExportSpaceMixin, TransformMixin, PsxBoneExportMixin, TransformSourceMixin):
     object_eval_state: EnumProperty(
         items=object_eval_state_items,
         name='Object Evaluation State',
@@ -54,11 +44,6 @@ class PskExportMixin(ExportSpaceMixin, TransformMixin, PsxBoneExportMixin):
         default=False,
         description='Export VTXNORMS section.'
     )
-    transform_source: EnumProperty(
-        items=transform_source_items,
-        name='Transform Source',
-        default='SCENE'
-    )
 
 
 class PSK_PG_export(PropertyGroup, PskExportMixin):
@@ -66,7 +51,6 @@ class PSK_PG_export(PropertyGroup, PskExportMixin):
 
 
 _classes = (
-    PSK_PG_material_list_item,
     PSK_PG_material_name_list_item,
     PSK_PG_export,
 )

io_scene_psk_psa/psk/export/properties.pyi

@@ -0,0 +1,18 @@
+from ...shared.types import BpyCollectionProperty, ExportSpaceMixin, TransformMixin, PsxBoneExportMixin, TransformSourceMixin
+
+
+class PSK_PG_material_name_list_item:
+    material_name: str
+    index: int
+
+
+class PskExportMixin(ExportSpaceMixin, TransformMixin, PsxBoneExportMixin, TransformSourceMixin):
+    object_eval_state: str
+    material_order_mode: str
+    material_name_list: BpyCollectionProperty[PSK_PG_material_name_list_item]
+    material_name_list_index: int
+    should_export_vertex_normals: bool
+
+
+class PSK_PG_export(PskExportMixin):
+    pass

io_scene_psk_psa/psk/export/ui.py

@@ -1,13 +1,43 @@
 import bpy
 from bpy.types import UIList
+from typing import cast as typing_cast
+
+from .properties import PSK_PG_material_name_list_item
 
 
 class PSK_UL_material_names(UIList):
-    def draw_item(self, context, layout, data, item, icon, active_data, active_propname, index):
+    def draw_item(
+        self,
+        context,
+        layout,
+        data,
+        item,
+        icon,
+        active_data,
+        active_property,
+        index,
+        flt_flag
+    ):
         row = layout.row()
+        item = typing_cast(PSK_PG_material_name_list_item, item)
         material = bpy.data.materials.get(item.material_name, None)
-        icon_value = layout.icon(material) if material else 0
-        row.prop(item, 'material_name', text='', emboss=False, icon_value=icon_value, icon='BLANK1' if icon_value == 0 else 'NONE')
+
+        # If the material is not found by name and the name is not 'None', show a not found icon
+        if item.material_name == 'None':
+            icon = 'NODE_MATERIAL'
+        else:
+            icon = 'NOT_FOUND' if material is None else 'NONE'
+
+        row.prop(item, 'material_name', text='', emboss=False,
+                 icon_value=layout.icon(material) if material else 0,
+                 icon=icon)
+
+        # Add right-aligned "Not Found" label if material is not found
+        if item.material_name != 'None' and material is None:
+            label_row = row.row()
+            label_row.alignment = 'RIGHT'
+            label_row.enabled = False
+            label_row.label(text='Not Found')
 
 
 _classes = (

io_scene_psk_psa/psk/import_/operators.py

@@ -163,7 +163,7 @@ class PSK_OT_import_drag_and_drop(Operator, PskImportMixin):
 
 
 # TODO: move to another file
-class PSK_FH_import(FileHandler):
+class PSK_FH_file_handler(FileHandler):
     bl_idname = 'PSK_FH_import'
     bl_label = 'Unreal PSK'
     bl_import_operator = PSK_OT_import_drag_and_drop.bl_idname
@@ -178,7 +178,7 @@ class PSK_FH_import(FileHandler):
 _classes = (
     PSK_OT_import,
     PSK_OT_import_drag_and_drop,
-    PSK_FH_import,
+    PSK_FH_file_handler,
 )
 
 from bpy.utils import register_classes_factory

io_scene_psk_psa/psk/importer.py

@@ -4,7 +4,7 @@ import numpy as np
 
 from bpy.types import Context, Object, VertexGroup, ArmatureModifier, FloatColorAttribute
 from mathutils import Matrix, Quaternion, Vector
-from typing import List, Optional, cast as typing_cast
+from typing import cast as typing_cast
 
 from psk_psa_py.psk.data import Psk
 from psk_psa_py.shared.data import PsxBone
@@ -25,7 +25,7 @@ class PskImportOptions:
         self.bone_length = 1.0
         self.should_import_materials = True
         self.scale = 1.0
-        self.bdk_repository_id = None
+        self.bdk_repository_id: str | None = None
 
 
 class ImportBone:
@@ -35,12 +35,11 @@ class ImportBone:
     def __init__(self, index: int, psk_bone: PsxBone):
         self.index: int = index
         self.psk_bone: PsxBone = psk_bone
-        self.parent: Optional[ImportBone] = None
+        self.parent: ImportBone | None = None
         self.local_rotation: Quaternion = Quaternion()
         self.local_translation: Vector = Vector()
         self.world_rotation_matrix: Matrix = Matrix()
         self.world_matrix: Matrix = Matrix()
-        self.vertex_group = None
         self.original_rotation: Quaternion = Quaternion()
         self.original_location: Vector = Vector()
         self.post_rotation: Quaternion = Quaternion()
@@ -48,9 +47,9 @@ class ImportBone:
 
 class PskImportResult:
     def __init__(self):
-        self.warnings: List[str] = []
-        self.armature_object: Optional[Object] = None
-        self.mesh_object: Optional[Object] = None
+        self.warnings: list[str] = []
+        self.armature_object: Object | None = None
+        self.mesh_object: Object | None = None
 
     @property
     def root_object(self) -> Object:
@@ -83,7 +82,7 @@ def import_psk(psk: Psk, context: Context, name: str, options: PskImportOptions)
 
         bpy.ops.object.mode_set(mode='EDIT')
 
-        import_bones = []
+        import_bones: list[ImportBone] = []
 
         for bone_index, psk_bone in enumerate(psk.bones):
             import_bone = ImportBone(bone_index, psk_bone)
@@ -107,10 +106,16 @@ def import_psk(psk: Psk, context: Context, name: str, options: PskImportOptions)
             bone.world_rotation_matrix = bone.local_rotation.conjugated().to_matrix()
             bone.world_rotation_matrix.rotate(parent.world_rotation_matrix)
 
+        # Create all the bones up-front.
+        # This allows us to set up the parent-child relationships properly even if the parent bone comes after the child bone in the PSK file.
         for import_bone in import_bones:
             bone_name = import_bone.psk_bone.name.decode('utf-8')
             edit_bone = armature_data.edit_bones.new(bone_name)
 
+        for import_bone in import_bones:
+            bone_name = import_bone.psk_bone.name.decode('utf-8')
+            edit_bone = armature_data.edit_bones[bone_name]
+
             if import_bone.parent is not None:
                 edit_bone.parent = armature_data.edit_bones[import_bone.psk_bone.parent_index]
             else:
@@ -257,7 +262,7 @@ def import_psk(psk: Psk, context: Context, name: str, options: PskImportOptions)
         # Weights
         # Get a list of all bones that have weights associated with them.
         vertex_group_bone_indices = set(map(lambda weight: weight.bone_index, psk.weights))
-        vertex_groups: List[Optional[VertexGroup]] = [None] * len(psk.bones)
+        vertex_groups: list[VertexGroup | None] = [None] * len(psk.bones)
         for bone_index, psk_bone in map(lambda x: (x, psk.bones[x]), vertex_group_bone_indices):
             vertex_groups[bone_index] = mesh_object.vertex_groups.new(name=psk_bone.name.decode('windows-1252'))
 

io_scene_psk_psa/psk/properties.pyi

@@ -0,0 +1,23 @@
+class PSX_PG_material:
+    mesh_triangle_type: str
+    mesh_triangle_bit_flags: set[str]
+
+
+class PskImportMixin:
+    should_import_vertex_colors: bool
+    vertex_color_space: str
+    should_import_vertex_normals: bool
+    should_import_extra_uvs: bool
+    components: str
+    should_import_mesh: bool
+    should_import_materials: bool
+    should_import_armature: bool
+    bone_length: float
+    should_import_shape_keys: bool
+    scale: float
+    bdk_repository_id: str
+
+
+def triangle_type_and_bit_flags_to_poly_flags(mesh_triangle_type: str, mesh_triangle_bit_flags: set[str]) -> int: ...
+
+def poly_flags_to_triangle_type_and_bit_flags(poly_flags: int) -> tuple[str, set[str]]: ...

io_scene_psk_psa/shared/dfs.py

@@ -5,7 +5,7 @@ These functions are used to iterate over objects in a collection or view layer i
 instances. This is useful for exporters that need to traverse the object hierarchy in a predictable order.
 """
 
-from typing import Optional, Set, Iterable, List
+from typing import Iterable
 
 from bpy.types import Collection, Object, ViewLayer, LayerCollection
 from mathutils import Matrix
@@ -15,7 +15,7 @@ class DfsObject:
     """
     Represents an object in a depth-first search.
     """
-    def __init__(self, obj: Object, instance_objects: List[Object], matrix_world: Matrix):
+    def __init__(self, obj: Object, instance_objects: list[Object], matrix_world: Matrix):
         self.obj = obj
         self.instance_objects = instance_objects
         self.matrix_world = matrix_world
@@ -85,9 +85,9 @@ def dfs_collection_objects(collection: Collection, visible_only: bool = False) -
 
 def _dfs_collection_objects_recursive(
         collection: Collection,
-        instance_objects: Optional[List[Object]] = None,
+        instance_objects: list[Object] | None = None,
         matrix_world: Matrix = Matrix.Identity(4),
-        visited: Optional[Set[Object]]=None
+        visited: set[Object] | None = None
 ) -> Iterable[DfsObject]:
     """
     Depth-first search of objects in a collection, including recursing into instances.

io_scene_psk_psa/shared/helpers.py

@@ -1,9 +1,11 @@
 import bpy
 from collections import Counter
-from typing import List, Iterable, Optional, Dict, Tuple, cast as typing_cast
-from bpy.types import Armature, AnimData, Collection, Context, Object, ArmatureModifier, SpaceProperties
+from typing import Iterable, cast as typing_cast
+from bpy.types import Armature, AnimData, Collection, Context, Object, ArmatureModifier, SpaceProperties, PropertyGroup, Material
 from mathutils import Matrix, Vector, Quaternion as BpyQuaternion
-from psk_psa_py.shared.data import PsxBone, Vector3, Quaternion
+from psk_psa_py.shared.data import PsxBone, Quaternion, Vector3
+
+from ..shared.types import BpyCollectionProperty, PSX_PG_bone_collection_list_item
 
 
 def rgb_to_srgb(c: float) -> float:
@@ -23,7 +25,11 @@ def get_nla_strips_in_frame_range(animation_data: AnimData, frame_min: float, fr
                 yield strip
 
 
-def populate_bone_collection_list(bone_collection_list, armature_objects: Iterable[Object], primary_key: str = 'OBJECT'):
+def populate_bone_collection_list(
+        bone_collection_list: BpyCollectionProperty[PSX_PG_bone_collection_list_item], 
+        armature_objects: Iterable[Object],
+        primary_key: str = 'OBJECT'
+        ):
     """
     Updates the bone collection list.
 
@@ -63,37 +69,40 @@ def populate_bone_collection_list(bone_collection_list, armature_objects: Iterab
     unique_armature_data = set()
 
     for armature_object in armature_objects:
-        armature = typing_cast(Armature, armature_object.data)
+        armature_data = typing_cast(Armature, armature_object.data)
 
-        if armature is None:
+        if armature_data is None:
             continue
 
-        if primary_key == 'DATA' and armature_object.data in unique_armature_data:
+        if primary_key == 'DATA':
+            if armature_data in unique_armature_data:
                 # Skip this armature since we have already added an entry for it and we are using the data as the key.
                 continue
+            unique_armature_data.add(armature_data)
         
-        unique_armature_data.add(armature_object.data)
+        unassigned_bone_count = sum(map(lambda bone: 1 if len(bone.collections) == 0 else 0, armature_data.bones))
 
+        if unassigned_bone_count > 0:
             item = bone_collection_list.add()
             item.armature_object_name = armature_object.name
-        item.armature_data_name = armature_object.data.name if armature_object.data else ''
-        item.name = 'Unassigned' # TODO: localize
+            item.armature_data_name = armature_data.name if armature_data else ''
+            item.name = 'Unassigned'
             item.index = -1
             # Count the number of bones without an assigned bone collection
-        item.count = sum(map(lambda bone: 1 if len(bone.collections) == 0 else 0, armature.bones))
+            item.count = unassigned_bone_count
             item.is_selected = unassigned_collection_is_selected
 
-        for bone_collection_index, bone_collection in enumerate(armature.collections_all):
+        for bone_collection_index, bone_collection in enumerate(armature_data.collections_all):
             item = bone_collection_list.add()
             item.armature_object_name = armature_object.name
-            item.armature_data_name = armature_object.data.name if armature_object.data else ''
+            item.armature_data_name = armature_data.name if armature_data else ''
             item.name = bone_collection.name
             item.index = bone_collection_index
             item.count = len(bone_collection.bones)
             item.is_selected = bone_collection.name in selected_assigned_collection_names if has_selected_collections else True
 
 
-def get_export_bone_names(armature_object: Object, bone_filter_mode: str, bone_collection_indices: Iterable[int]) -> List[str]:
+def get_export_bone_names(armature_object: Object, bone_filter_mode: str, bone_collection_indices: Iterable[int]) -> list[str]:
     """
     Returns a sorted list of bone indices that should be exported for the given bone filter mode and bone collections.
 
@@ -146,32 +155,8 @@ def get_export_bone_names(armature_object: Object, bone_filter_mode: str, bone_c
     # We use the bone names for the return values because the bone name is a more universal way of referencing them.
     # For example, users of this function may modify bone lists, which would invalidate the indices and require an
     # index mapping scheme to resolve it. Using strings is more comfy and results in less code downstream.
-    instigator_bone_names = [bones[x[1]].name if x[1] is not None else None for x in bone_indices]
     bone_names = [bones[x[0]].name for x in bone_indices]
 
-    # Ensure that the hierarchy we are sending back has a single root bone.
-    # TODO: This is only relevant if we are exporting a single armature; how should we reorganize this call?
-    bone_indices = [x[0] for x in bone_indices]
-    root_bones = [bones[bone_index] for bone_index in bone_indices if bones[bone_index].parent is None]
-    if len(root_bones) > 1:
-        # There is more than one root bone.
-        # Print out why each root bone was included by linking it to one of the explicitly included bones.
-        root_bone_names = [bone.name for bone in root_bones]
-        for root_bone_name in root_bone_names:
-            bone_name = root_bone_name
-            while True:
-                # Traverse the instigator chain until the end to find the true instigator bone.
-                # TODO: in future, it would be preferential to have a readout of *all* instigator bones.
-                instigator_bone_name = instigator_bone_names[bone_names.index(bone_name)]
-                if instigator_bone_name is None:
-                    print(f'Root bone "{root_bone_name}" was included because {bone_name} was marked for export')
-                    break
-                bone_name = instigator_bone_name
-
-        raise RuntimeError('Exported bone hierarchy must have a single root bone.\n'
-                           f'The bone hierarchy marked for export has {len(root_bones)} root bones: {root_bone_names}.\n'
-                           f'Additional debugging information has been written to the console.')
-
     return bone_names
 
 
@@ -186,121 +171,95 @@ def convert_string_to_cp1252_bytes(string: str) -> bytes:
         raise RuntimeError(f'The string "{string}" contains characters that cannot be encoded in the Windows-1252 codepage') from e
 
 
-# TODO: Perhaps export space should just be a transform matrix, since the below is not actually used unless we're using WORLD space.
 def create_psx_bones_from_blender_bones(
-        bones: List[bpy.types.Bone],
-        export_space: str = 'WORLD',
-        armature_object_matrix_world: Matrix = Matrix.Identity(4),
-        scale = 1.0,
-        forward_axis: str = 'X',
-        up_axis: str = 'Z',
-        root_bone: Optional = None,
-) -> List[PsxBone]:
+        bones: list[bpy.types.Bone],
+        armature_object_matrix_world: Matrix,
+) -> list[PsxBone]:
+    """
+    Creates PSX bones from the given Blender bones.
     
-    scale_matrix = Matrix.Scale(scale, 4)
+    The bones are in world space based on the armature object's world matrix.
+    """
+    # Apply the scale of the armature object to the bone location.
+    _, _, armature_object_scale = armature_object_matrix_world.decompose()
 
-    coordinate_system_transform = get_coordinate_system_transform(forward_axis, up_axis)
-    coordinate_system_default_rotation = coordinate_system_transform.to_quaternion()
-
-    psx_bones = []
+    psx_bones: list[PsxBone] = []
     for bone in bones:
         psx_bone = PsxBone()
         psx_bone.name = convert_string_to_cp1252_bytes(bone.name)
 
+        if bone.parent is not None:
             try:
                 parent_index = bones.index(bone.parent)
                 psx_bone.parent_index = parent_index
                 psx_bones[parent_index].children_count += 1
             except ValueError:
-            psx_bone.parent_index = 0
+                pass
 
         if bone.parent is not None:
+            # Child bone.
             rotation = bone.matrix.to_quaternion().conjugated()
             inverse_parent_rotation = bone.parent.matrix.to_quaternion().inverted()
             parent_head = inverse_parent_rotation @ bone.parent.head
             parent_tail = inverse_parent_rotation @ bone.parent.tail
             location = (parent_tail - parent_head) + bone.head
-        elif bone.parent is None and root_bone is not None:
-            # This is a special case for the root bone when export
-            # Because the root bone and child bones are in different spaces, we need to treat the root bone of this
-            # armature as though it were a child bone.
-            bone_rotation = bone.matrix.to_quaternion().conjugated()
-            local_rotation = armature_object_matrix_world.to_3x3().to_quaternion().conjugated()
-            rotation = bone_rotation @ local_rotation
-            translation, _, scale = armature_object_matrix_world.decompose()
-            # Invert the scale of the armature object matrix.
-            inverse_scale_matrix = Matrix.Identity(4)
-            inverse_scale_matrix[0][0] = 1.0 / scale.x
-            inverse_scale_matrix[1][1] = 1.0 / scale.y
-            inverse_scale_matrix[2][2] = 1.0 / scale.z
-
-            translation = translation @ inverse_scale_matrix
-            location = translation + bone.head
         else:
-            def get_armature_local_matrix():
-                match export_space:
-                    case 'WORLD':
-                        return armature_object_matrix_world
-                    case 'ARMATURE':
-                        return Matrix.Identity(4)
-                    case 'ROOT':
-                        return bone.matrix.inverted()
-                    case _:
-                        assert False, f'Invalid export space: {export_space}'
-
-            armature_local_matrix = get_armature_local_matrix()
-            location = armature_local_matrix @ bone.head
-            location = coordinate_system_transform @ location
+            location = armature_object_matrix_world @ bone.head
             bone_rotation = bone.matrix.to_quaternion().conjugated()
-            local_rotation = armature_local_matrix.to_3x3().to_quaternion().conjugated()
-            rotation = bone_rotation @ local_rotation
+            rotation = bone_rotation @ armature_object_matrix_world.to_3x3().to_quaternion()
             rotation.conjugate()
-            rotation = coordinate_system_default_rotation @ rotation
 
-        location = scale_matrix @ location
-
-        # If the armature object has been scaled, we need to scale the bone's location to match.
-        _, _, armature_object_scale = armature_object_matrix_world.decompose()
         location.x *= armature_object_scale.x
         location.y *= armature_object_scale.y
         location.z *= armature_object_scale.z
 
-        psx_bone.location.x = location.x
-        psx_bone.location.y = location.y
-        psx_bone.location.z = location.z
-
-        psx_bone.rotation.w = rotation.w
-        psx_bone.rotation.x = rotation.x
-        psx_bone.rotation.y = rotation.y
-        psx_bone.rotation.z = rotation.z
+        # Copy the calculated location and rotation to the bone.
+        psx_bone.location = convert_vector_to_vector3(location)
+        psx_bone.rotation = convert_bpy_quaternion_to_psx_quaternion(rotation)
 
         psx_bones.append(psx_bone)
 
     return psx_bones
 
 
+class PsxBoneResult:
+    def __init__(self, psx_bone: PsxBone, armature_object: Object | None) -> None:
+        self.psx_bone: PsxBone = psx_bone
+        self.armature_object: Object | None = armature_object
+
+
 class PsxBoneCreateResult:
     def __init__(self,
-                 bones: List[Tuple[PsxBone, Optional[Object]]],  # List of tuples of (psx_bone, armature_object)
-                 armature_object_root_bone_indices: Dict[Object, int],
-                 armature_object_bone_names: Dict[Object, List[str]],
+                 bones: list[PsxBoneResult],  # List of tuples of (psx_bone, armature_object)
+                 armature_object_root_bone_indices: dict[Object, int],
+                 armature_object_bone_names: dict[Object, list[str]],
                  ):
         self.bones = bones
         self.armature_object_root_bone_indices = armature_object_root_bone_indices
         self.armature_object_bone_names = armature_object_bone_names
 
-    @property
-    def has_false_root_bone(self) -> bool:
-        return len(self.bones) > 0 and self.bones[0][1] is None
+
+def convert_vector_to_vector3(vector: Vector) -> Vector3:
+    """
+    Convert a Blender mathutils.Vector to a psk_psa_py Vector3.
+    """
+    vector3 = Vector3()
+    vector3.x = vector.x
+    vector3.y = vector.y
+    vector3.z = vector.z
+    return vector3
 
 
-def convert_bpy_quaternion_to_psx_quaternion(other: BpyQuaternion) -> Quaternion:
-    quaternion = Quaternion()
-    quaternion.x = other.x
-    quaternion.y = other.y
-    quaternion.z = other.z
-    quaternion.w = other.w
-    return quaternion
+def convert_bpy_quaternion_to_psx_quaternion(quaternion: BpyQuaternion) -> Quaternion:
+    """
+    Convert a Blender mathutils.Quaternion to a psk_psa_py Quaternion.
+    """
+    psx_quaternion = Quaternion()
+    psx_quaternion.x = quaternion.x
+    psx_quaternion.y = quaternion.y
+    psx_quaternion.z = quaternion.z
+    psx_quaternion.w = quaternion.w
+    return psx_quaternion
 
 
 class PsxBoneCollection:
@@ -313,15 +272,71 @@ class PsxBoneCollection:
         self.index = index
 
 
+class ObjectNode:
+    def __init__(self, obj: Object):
+        self.object = obj
+        self.parent: ObjectNode | None = None
+        self.children: list[ObjectNode] = []
+    
+    @property
+    def root(self):
+        """
+        Gets the root in the object hierarchy. This can return itself if this node has no parent.
+        """
+        n = self
+        while n.parent is not None:
+            n = n.parent
+        return n
+
+
+class ObjectTree:
+    '''
+    A tree of the armature objects based on their hierarchy.
+    '''
+    def __init__(self, objects: Iterable[Object]):
+        self.root_nodes: list[ObjectNode] = []
+        object_node_map: dict[Object, ObjectNode] = {x: ObjectNode(x) for x in objects}
+        
+        for obj, object_node in object_node_map.items():
+            if obj.parent in object_node_map:
+                parent_node = object_node_map[obj.parent]
+                object_node.parent = parent_node
+                parent_node.children.append(object_node)
+            else:
+                self.root_nodes.append(object_node)
+
+    def __iter__(self):
+        """
+        An depth-first iterator over the armature tree.
+        """
+        node_stack = [] + self.root_nodes
+        while node_stack:
+            node = node_stack.pop()
+            yield node
+            node_stack = node.children + node_stack
+    
+    def objects_iterator(self):
+        for node in self:
+            yield node.object
+    
+    def dump(self):
+        # Print out the hierarchy of armature objects for debugging using the root nodes, with indentation to show parent-child relationships.
+        for root_node in self.root_nodes:
+            def print_object_node(node: ObjectNode, indent: int = 0):
+                print(' ' * indent + f'- {node.object.name}')
+                for child_node in node.children:
+                    print_object_node(child_node, indent + 2)
+            print_object_node(root_node)
+
+
 def create_psx_bones(
-        armature_objects: List[Object],
+        armature_objects: list[Object],
         export_space: str = 'WORLD',
-        root_bone_name: str = 'ROOT',
         forward_axis: str = 'X',
         up_axis: str = 'Z',
         scale: float = 1.0,
         bone_filter_mode: str = 'ALL',
-        bone_collection_indices: Optional[List[PsxBoneCollection]] = None,
+        bone_collection_indices: list[PsxBoneCollection] | None = None,
         bone_collection_primary_key: str = 'OBJECT',
 ) -> PsxBoneCreateResult:
     """
@@ -332,15 +347,19 @@ def create_psx_bones(
     if bone_collection_indices is None:
         bone_collection_indices = []
 
-    bones: List[Tuple[PsxBone, Optional[Object]]] = []
+    armature_tree = ObjectTree(armature_objects)
 
-    if export_space != 'WORLD' and len(armature_objects) >= 2:
-        armature_object_names = [armature_object.name for armature_object in armature_objects]
-        raise RuntimeError(f'When exporting multiple armatures, the Export Space must be World.\n' \
-            f'The following armatures are attempting to be exported: {armature_object_names}')
+    if len(armature_tree.root_nodes) >= 2:
+        root_bone_names = []
+        for root_node in armature_tree.root_nodes:
+            root_bone_names.append(root_node.object.name)
+        raise RuntimeError(
+            f'Multiple root armature objects were found: {root_bone_names}.\n'
+            'Only one root armature object is allowed.\n'
+            'To use multiple armature objects, parent them to one another in a hierarchy using Bone parenting.'
+        )
 
-    coordinate_system_matrix = get_coordinate_system_transform(forward_axis, up_axis)
-    coordinate_system_default_rotation = coordinate_system_matrix.to_quaternion()
+    # TODO: confirm this to be working with non-bone parented armature hierarchies.
 
     total_bone_count = 0
     for armature_object in filter(lambda x: x.data is not None, armature_objects):
@@ -348,9 +367,9 @@ def create_psx_bones(
         total_bone_count += len(armature_data.bones)
 
     # Store the bone names to be exported for each armature object.
-    armature_object_bone_names: Dict[Object, List[str]] = dict()
+    armature_object_bone_names: dict[Object, list[str]] = dict()
     for armature_object in  armature_objects:
-        armature_bone_collection_indices: List[int] = []
+        armature_bone_collection_indices: list[int] = []
         match bone_collection_primary_key:
             case 'OBJECT':
                 armature_bone_collection_indices.extend([x.index for x in bone_collection_indices if x.armature_object_name == armature_object.name])
@@ -363,50 +382,66 @@ def create_psx_bones(
 
     # Store the index of the root bone for each armature object.
     # We will need this later to correctly assign vertex weights.
-    armature_object_root_bone_indices: Dict[Optional[Object], int] = dict()
-
-    if len(armature_objects) == 0 or total_bone_count == 0:
-        # If the mesh has no armature object or no bones, simply assign it a dummy bone at the root to satisfy the
-        # requirement that a PSK file must have at least one bone.
-        psx_bone = PsxBone()
-        psx_bone.name = convert_string_to_cp1252_bytes(root_bone_name)
-        psx_bone.flags = 0
-        psx_bone.children_count = 0
-        psx_bone.parent_index = 0
-        psx_bone.location = Vector3.zero()
-        psx_bone.rotation = convert_bpy_quaternion_to_psx_quaternion(coordinate_system_default_rotation)
-        bones.append((psx_bone, None))
-
-        armature_object_root_bone_indices[None] = 0
-    else:
-        # If we have multiple armature objects, create a root bone at the world origin.
-        if len(armature_objects) > 1:
-            psx_bone = PsxBone()
-            psx_bone.name = convert_string_to_cp1252_bytes(root_bone_name)
-            psx_bone.flags = 0
-            psx_bone.children_count = total_bone_count
-            psx_bone.parent_index = 0
-            psx_bone.location = Vector3.zero()
-            psx_bone.rotation = convert_bpy_quaternion_to_psx_quaternion(coordinate_system_default_rotation)
-            bones.append((psx_bone, None))
-
-            armature_object_root_bone_indices[None] = 0
-
-        root_bone = bones[0][0] if len(bones) > 0 else None
+    armature_object_root_bone_indices: dict[Object | None, int] = dict()
+    bones: list[PsxBoneResult] = []
 
+    # Iterate through all the armature objects.
     for armature_object in armature_objects:
         bone_names = armature_object_bone_names[armature_object]
         armature_data = typing_cast(Armature, armature_object.data)
         armature_bones = [armature_data.bones[bone_name] for bone_name in bone_names]
 
+        # Ensure that we don't have multiple root bones in this armature.
+        root_bone_count = sum(1 for bone in armature_bones if bone.parent is None)
+        if root_bone_count > 1:
+            raise RuntimeError(f'Armature object \'{armature_object.name}\' has multiple root bones. '
+                               f'Only one root bone is allowed per armature.'
+                               )
+
         armature_psx_bones = create_psx_bones_from_blender_bones(
             bones=armature_bones,
-                export_space=export_space,
             armature_object_matrix_world=armature_object.matrix_world,
-                scale=scale,
-                forward_axis=forward_axis,
-                up_axis=up_axis,
-                root_bone=root_bone,
+        )
+
+        if len(armature_psx_bones) == 0:
+            continue
+
+        # We have the bones in world space. If we are attaching this armature to a parent bone, we need to convert
+        # the root bone to be relative to the target parent bone.
+        if armature_object.parent in armature_objects:
+            match armature_object.parent_type:
+                case 'BONE':
+                    # Parent to a bone in the parent armature object.
+                    # We just need to get the world-space location of each of the bones and get the relative pose, then
+                    # assign that location and rotation to the root bone.
+                    parent_bone_name = armature_object.parent_bone
+
+                    if parent_bone_name == '':
+                        raise RuntimeError(f'Armature object \'{armature_object.name}\' is parented to a bone but no parent bone name is specified.')
+
+                    parent_armature_data = typing_cast(Armature, armature_object.parent.data)
+                    if parent_armature_data is None:
+                        raise RuntimeError(f'Parent object \'{armature_object.parent.name}\' is not an armature.')
+                    try:
+                        parent_bone = parent_armature_data.bones[parent_bone_name]
+                    except KeyError:
+                        raise RuntimeError(f'Bone \'{parent_bone_name}\' could not be found in armature \'{armature_object.parent.name}\'.')    
+                    
+                    parent_bone_world_matrix = armature_object.parent.matrix_world @ parent_bone.matrix_local.to_4x4()
+                    parent_bone_world_location, parent_bone_world_rotation, _ = parent_bone_world_matrix.decompose()
+
+                    # Convert the root bone location to be relative to the parent bone.
+                    root_bone = armature_psx_bones[0]
+                    root_bone_location = Vector((root_bone.location.x, root_bone.location.y, root_bone.location.z))
+                    relative_location = parent_bone_world_rotation.inverted() @ (root_bone_location - parent_bone_world_location)
+                    root_bone.location = convert_vector_to_vector3(relative_location)
+                    # Convert the root bone rotation to be relative to the parent bone.
+                    root_bone_rotation = BpyQuaternion((root_bone.rotation.w, root_bone.rotation.x, root_bone.rotation.y, root_bone.rotation.z))
+                    relative_rotation = parent_bone_world_rotation.inverted() @ root_bone_rotation
+                    root_bone.rotation = convert_bpy_quaternion_to_psx_quaternion(relative_rotation)
+                case _:
+                    raise RuntimeError(f'Unhandled parent type ({armature_object.parent_type}) for object {armature_object.name}.\n'
+                                        f'Parent type must be \'Bone\'.'
                                         )
 
         # If we are appending these bones to an existing list of bones, we need to adjust the parent indices for
@@ -418,19 +453,109 @@ def create_psx_bones(
 
         armature_object_root_bone_indices[armature_object] = len(bones)
 
-            bones.extend((psx_bone, armature_object) for psx_bone in armature_psx_bones)
+        bones.extend(PsxBoneResult(psx_bone, armature_object) for psx_bone in armature_psx_bones)
+
+    # Check that we have any bones to export at this point. If not, we can skip the rest of the processing.
+    if len(bones) == 0:
+        return PsxBoneCreateResult(
+            bones=[],
+            armature_object_root_bone_indices=armature_object_root_bone_indices,
+            armature_object_bone_names=armature_object_bone_names,
+        )
+
+    # Check if any of the armatures are parented to one another.
+    # If so, adjust the hierarchy as though they are part of the same armature object.
+    # This will let us re-use rig components without destructively joining them.
+    for armature_object in armature_objects:
+        if armature_object.parent not in armature_objects:
+            continue
+
+        # This armature object is parented to another armature object that we are exporting.
+        # First fetch the root bone indices for the two armature objects.
+        root_bone_index = armature_object_root_bone_indices.get(armature_object, None)
+        parent_root_bone_index = armature_object_root_bone_indices.get(armature_object.parent, None)
+
+        if root_bone_index is None or parent_root_bone_index is None:
+            raise RuntimeError(f'Could not find root bone index for armature object \'{armature_object.name}\' or its parent \'{armature_object.parent.name}\'.\n'
+                               'This likely means that one of the armatures does not have any bones that are being exported, which is not allowed when using armature parenting between multiple armatures.'
+                               )
+
+        match armature_object.parent_type:
+            case 'OBJECT':
+                # Parent this armature's root bone to the root bone of the parent object.
+                bones[root_bone_index].psx_bone.parent_index = parent_root_bone_index
+            case 'BONE':
+                # Parent this armature's root bone to the specified bone in the parent.
+                new_parent_index = None
+                for bone_index, bone in enumerate(bones):
+                    if bone.psx_bone.name == convert_string_to_cp1252_bytes(armature_object.parent_bone) and bone.armature_object == armature_object.parent:
+                        new_parent_index = bone_index
+                        break
+                if new_parent_index == None:
+                    raise RuntimeError(f'Bone \'{armature_object.parent_bone}\' could not be found in armature \'{armature_object.parent.name}\'.')
+                bones[root_bone_index].psx_bone.parent_index = new_parent_index
+            case _:
+                raise RuntimeError(f'Unhandled parent type ({armature_object.parent_type}) for object {armature_object.name}.\n'
+                                    f'Parent type must be \'Object\' or \'Bone\'.'
+                                    )
+
+    match export_space:
+        case 'WORLD':
+            # No action needed, bones are already in world space.
+            pass
+        case 'ARMATURE':
+            # The bone is in world-space. We need to convert it to armature (object) space.
+            # Get this from matrix_local.
+            root_bone, root_bone_armature_object = bones[0].psx_bone, bones[0].armature_object
+            if root_bone_armature_object is None:
+                raise RuntimeError('Cannot export to Armature space when multiple armatures are being exported.')
+        
+            armature_data = typing_cast(Armature, root_bone_armature_object.data)
+            matrix_local = armature_data.bones[root_bone.name.decode('windows-1252')].matrix_local
+            location, rotation, _ = matrix_local.decompose()
+            root_bone.location = convert_vector_to_vector3(location)
+            root_bone.rotation = convert_bpy_quaternion_to_psx_quaternion(rotation)
+        case 'ROOT':
+            # Zero out the root bone transforms.
+            root_bone = bones[0].psx_bone
+            root_bone.location = Vector3.zero()
+            root_bone.rotation = Quaternion.identity()
+        case _:
+            assert False, f'Invalid export space: {export_space}'
 
     # Check if there are bone name conflicts between armatures.
-    bone_name_counts = Counter(bone[0].name.decode('windows-1252').upper() for bone in bones)
+    bone_name_counts = Counter(bone.psx_bone.name.decode('windows-1252').upper() for bone in bones)
     for bone_name, count in bone_name_counts.items():
         if count > 1:
-            error_message = f'Found {count} bones with the name "{bone_name}". '
+            raise RuntimeError(
+                f'Found {count} bones with the name "{bone_name}". '
                 f'Bone names must be unique when compared case-insensitively.'
+            )
     
-            if len(armature_objects) > 1 and bone_name == root_bone_name.upper():
-                error_message += f' This is the name of the automatically generated root bone. Consider changing this '
-                f''
-                raise RuntimeError(error_message)
+    # Apply the scale to the bone locations.
+    for bone in bones:
+        bone.psx_bone.location.x *= scale
+        bone.psx_bone.location.y *= scale
+        bone.psx_bone.location.z *= scale
+    
+    coordinate_system_matrix = get_coordinate_system_transform(forward_axis, up_axis)
+    coordinate_system_default_rotation = coordinate_system_matrix.to_quaternion()
+
+    # Apply the coordinate system transform to the root bone.
+    root_psx_bone = bones[0].psx_bone
+    # Get transform matrix from root bone location and rotation.
+    root_bone_location = Vector((root_psx_bone.location.x, root_psx_bone.location.y, root_psx_bone.location.z))
+    root_bone_rotation = BpyQuaternion((root_psx_bone.rotation.w, root_psx_bone.rotation.x, root_psx_bone.rotation.y, root_psx_bone.rotation.z))
+    root_bone_matrix = (
+        Matrix.Translation(root_bone_location) @
+        root_bone_rotation.to_matrix().to_4x4()
+    )
+    root_bone_matrix = coordinate_system_default_rotation.inverted().to_matrix().to_4x4() @ root_bone_matrix
+    location, rotation, _ = root_bone_matrix.decompose()
+    root_psx_bone.location = convert_vector_to_vector3(location)
+    root_psx_bone.rotation = convert_bpy_quaternion_to_psx_quaternion(rotation)
+
+    convert_bpy_quaternion_to_psx_quaternion(coordinate_system_default_rotation)
 
     return PsxBoneCreateResult(
         bones=bones,
@@ -482,7 +607,7 @@ def get_armatures_for_mesh_objects(mesh_objects: Iterable[Object]):
     yield from armature_objects
 
 
-def get_collection_from_context(context: Context) -> Optional[Collection]:
+def get_collection_from_context(context: Context) -> Collection | None:
     if context.space_data is None or context.space_data.type != 'PROPERTIES':
         return None
     space_data = typing_cast(SpaceProperties, context.space_data)
@@ -492,7 +617,7 @@ def get_collection_from_context(context: Context) -> Optional[Collection]:
         return context.collection
 
 
-def get_collection_export_operator_from_context(context: Context) -> Optional[object]:
+def get_collection_export_operator_from_context(context: Context) -> PropertyGroup | None:
     collection = get_collection_from_context(context)
     if collection is None or collection.active_exporter_index is None:
         return None
@@ -500,3 +625,86 @@ def get_collection_export_operator_from_context(context: Context) -> Optional[ob
         return None
     exporter = collection.exporters[collection.active_exporter_index]
     return exporter.export_properties
+
+
+from ..shared.dfs import DfsObject, dfs_collection_objects, dfs_view_layer_objects
+from typing import Set
+from bpy.types import Depsgraph
+
+
+class PskInputObjects(object):
+    def __init__(self):
+        self.mesh_dfs_objects: list[DfsObject] = []
+        self.armature_objects: list[Object] = []
+
+
+def get_materials_for_mesh_objects(depsgraph: Depsgraph, mesh_objects: Iterable[Object]):
+    '''
+    Yields unique materials used by the given mesh objects.
+    If any mesh has no material slots or any empty material slots, None is yielded at the end.
+    '''
+    yielded_materials: Set[Material] = set()
+    has_none_material = False
+    for mesh_object in mesh_objects:
+        evaluated_mesh_object = mesh_object.evaluated_get(depsgraph)
+        # Check if mesh has no material slots or any empty material slots
+        if len(evaluated_mesh_object.material_slots) == 0:
+            has_none_material = True
+        else:
+            for material_slot in evaluated_mesh_object.material_slots:
+                material = material_slot.material
+                if material is None:
+                    has_none_material = True
+                else:
+                    if material not in yielded_materials:
+                        yielded_materials.add(material)
+                        yield material
+    # Yield None at the end if any mesh had no material slots or empty material slots
+    if has_none_material:
+        yield None
+
+
+def get_mesh_objects_for_collection(collection: Collection) -> Iterable[DfsObject]:
+    return filter(lambda x: x.obj.type == 'MESH', dfs_collection_objects(collection))
+
+
+def get_mesh_objects_for_context(context: Context) -> Iterable[DfsObject]:
+    if context.view_layer is None:
+        return
+    for dfs_object in dfs_view_layer_objects(context.view_layer):
+        if dfs_object.obj.type == 'MESH' and dfs_object.is_selected:
+            yield dfs_object
+
+
+def get_armature_for_mesh_object(mesh_object: Object) -> Object | None:
+    if mesh_object.type != 'MESH':
+        return None
+    # Get the first armature modifier with a non-empty armature object.
+    for modifier in filter(lambda x: x.type == 'ARMATURE', mesh_object.modifiers):
+            armature_modifier = typing_cast(ArmatureModifier, modifier)
+            if armature_modifier.object is not None:
+                return armature_modifier.object
+    return None
+
+
+def _get_psk_input_objects(mesh_dfs_objects: Iterable[DfsObject]) -> PskInputObjects:
+    mesh_dfs_objects = list(mesh_dfs_objects)
+    if len(mesh_dfs_objects) == 0:
+        raise RuntimeError('No mesh objects were found to export.')
+    input_objects = PskInputObjects()
+    input_objects.mesh_dfs_objects = mesh_dfs_objects
+    # Get the armature objects used on all the meshes being exported.
+    armature_objects = get_armatures_for_mesh_objects(map(lambda x: x.obj, mesh_dfs_objects))
+    # Sort them in hierarchy order.
+    input_objects.armature_objects = list(ObjectTree(armature_objects).objects_iterator())
+    return input_objects
+
+
+def get_psk_input_objects_for_context(context: Context) -> PskInputObjects:
+    mesh_objects = list(get_mesh_objects_for_context(context))
+    return _get_psk_input_objects(mesh_objects)
+
+
+def get_psk_input_objects_for_collection(collection: Collection) -> PskInputObjects:
+    mesh_objects = get_mesh_objects_for_collection(collection)
+    return _get_psk_input_objects(mesh_objects)

io_scene_psk_psa/shared/operators.py

@@ -0,0 +1,72 @@
+from bpy.types import Operator
+from bpy.props import BoolProperty
+
+from .types import PsxBoneExportMixin
+from typing import cast as typing_cast
+
+from .helpers import get_collection_export_operator_from_context, get_psk_input_objects_for_collection, populate_bone_collection_list
+
+
+
+class PSK_OT_bone_collection_list_populate(Operator):
+    bl_idname = 'psk.bone_collection_list_populate'
+    bl_label = 'Populate Bone Collection List'
+    bl_description = 'Populate the bone collection list from the armature that will be used in this collection export'
+    bl_options = {'INTERNAL'}
+
+    def execute(self, context):
+        export_operator = get_collection_export_operator_from_context(context)
+        if export_operator is None:
+            self.report({'ERROR_INVALID_CONTEXT'}, 'No valid export operator found in context')
+            return {'CANCELLED'}
+        if context.collection is None:
+            self.report({'ERROR_INVALID_CONTEXT'}, 'No active collection')
+            return {'CANCELLED'}
+        try:
+            input_objects = get_psk_input_objects_for_collection(context.collection)
+        except RuntimeError as e:
+            self.report({'ERROR_INVALID_CONTEXT'}, str(e))
+            return {'CANCELLED'}
+        if not input_objects.armature_objects:
+            self.report({'ERROR_INVALID_CONTEXT'}, 'No armature modifiers found on mesh objects')
+            return {'CANCELLED'}
+        export_operator = typing_cast(PsxBoneExportMixin, export_operator)
+
+        # Save and restore the selected status of the bones collections.
+        selected_status: dict[int, bool] = dict()
+        for bone_collection in export_operator.bone_collection_list:
+            selected_status[hash(bone_collection)] = bone_collection.is_selected
+
+        populate_bone_collection_list(export_operator.bone_collection_list, input_objects.armature_objects)
+
+        for bone_collection in export_operator.bone_collection_list:
+            bone_collection.is_selected = selected_status.get(hash(bone_collection), False)
+
+        return {'FINISHED'}
+
+
+class PSK_OT_bone_collection_list_select_all(Operator):
+    bl_idname = 'psk.bone_collection_list_select_all'
+    bl_label = 'Select All'
+    bl_description = 'Select all bone collections'
+    bl_options = {'INTERNAL'}
+
+    is_selected: BoolProperty(default=True)
+
+    def execute(self, context):
+        export_operator = get_collection_export_operator_from_context(context)
+        if export_operator is None:
+            self.report({'ERROR_INVALID_CONTEXT'}, 'No valid export operator found in context')
+            return {'CANCELLED'}
+        export_operator = typing_cast(PsxBoneExportMixin, export_operator)
+        for item in export_operator.bone_collection_list:
+            item.is_selected = self.is_selected
+        return {'FINISHED'}
+
+
+_classes = (
+    PSK_OT_bone_collection_list_populate,
+    PSK_OT_bone_collection_list_select_all,
+)
+from bpy.utils import register_classes_factory
+register, unregister = register_classes_factory(_classes)

io_scene_psk_psa/shared/semver.py

@@ -1,54 +0,0 @@
-from typing import Tuple
-
-class SemanticVersion(object):
-    def __init__(self, version: Tuple[int, int, int]):
-        self.major, self.minor, self.patch = version
-
-    def __iter__(self):
-        yield self.major
-        yield self.minor
-        yield self.patch
-
-    @staticmethod
-    def compare(lhs: 'SemanticVersion', rhs: 'SemanticVersion') -> int:
-        """
-        Compares two semantic versions.
-
-        Returns:
-            -1 if lhs < rhs
-             0 if lhs == rhs
-             1 if lhs > rhs
-        """
-        for l, r in zip(lhs, rhs):
-            if l < r:
-                return -1
-            if l > r:
-                return 1
-        return 0
-
-    def __str__(self):
-        return f'{self.major}.{self.minor}.{self.patch}'
-
-    def __repr__(self):
-        return str(self)
-
-    def __eq__(self, other):
-        return self.compare(self, other) == 0
-
-    def __ne__(self, other):
-        return not self == other
-
-    def __lt__(self, other):
-        return self.compare(self, other) == -1
-
-    def __le__(self, other):
-        return self.compare(self, other) <= 0
-
-    def __gt__(self, other):
-        return self.compare(self, other) == 1
-
-    def __ge__(self, other):
-        return self.compare(self, other) >= 0
-
-    def __hash__(self):
-        return hash((self.major, self.minor, self.patch))

io_scene_psk_psa/shared/types.py

@@ -1,12 +1,29 @@
+from typing import Generic, Iterable, Sized, TypeVar
 import bpy
 from bpy.props import CollectionProperty, EnumProperty, StringProperty, IntProperty, BoolProperty, FloatProperty
 from bpy.types import PropertyGroup, UIList, UILayout, Context, AnyType, Panel
 
+T = TypeVar('T')
+
+# Don't actually use this, this is just for typing.
+class BpyCollectionProperty(Generic[T], Iterable[T], Sized):
+    def add(self) -> T:
+        return T() # type: ignore
+
+    def clear(self) -> None:
+        pass
+
+    def move(self, src_index: int, dst_index: int):
+        pass
+
+    def remove(self, index: int):
+        pass
+
 
 class PSX_UL_bone_collection_list(UIList):
 
-    def draw_item(self, _context: Context, layout: UILayout, _data: AnyType, item: AnyType, _icon: int,
-                  _active_data: AnyType, _active_property: str, _index: int = 0, _flt_flag: int = 0):
+    def draw_item(self, context: Context, layout: UILayout, data: AnyType, item: AnyType, icon: int,
+                  active_data: AnyType, active_property: str, index: int = 0, flt_flag: int = 0):
         row = layout.row()
 
         row.prop(item, 'is_selected', text=getattr(item, 'name'))
@@ -27,6 +44,9 @@ class PSX_PG_bone_collection_list_item(PropertyGroup):
     count: IntProperty()
     is_selected: BoolProperty(default=False)
 
+    def __hash__(self) -> int:
+        return hash(f'{self.name}/{self.armature_object_name}/{self.armature_data_name}')
+
 
 class PSX_PG_action_export(PropertyGroup):
     group: StringProperty(name='Group', description='The group of the sequence', maxlen=64)
@@ -45,7 +65,7 @@ class PSX_PT_action(Panel):
 
     @classmethod
     def poll(cls, context: 'Context'):
-        return context.active_object and context.active_object.type == 'ARMATURE' and context.active_action is not None
+        return context.active_object is not None and context.active_object.type == 'ARMATURE' and context.active_action is not None
 
     def draw(self, context: 'Context'):
         action = context.active_action
@@ -87,13 +107,13 @@ up_items = (
 )
 
 
-def forward_axis_update(self, __context):
+def forward_axis_update(self, context):
     if self.forward_axis == self.up_axis:
         # Automatically set the up axis to the next available axis
         self.up_axis = next((axis for axis in axis_identifiers if axis != self.forward_axis), 'Z')
 
 
-def up_axis_update(self, __context):
+def up_axis_update(self, context):
     if self.up_axis == self.forward_axis:
         # Automatically set the forward axis to the next available axis
         self.forward_axis = next((axis for axis in axis_identifiers if axis != self.up_axis), 'X')
@@ -138,6 +158,17 @@ class ExportSpaceMixin:
         default='WORLD'
     )
  
+transform_source_items = (
+    ('SCENE', 'Scene', 'Use the scene transform settings'),
+    ('CUSTOM', 'Custom', 'Use custom transform settings'),
+)
+
+class TransformSourceMixin:
+    transform_source: EnumProperty(
+        items=transform_source_items,
+        name='Transform Source',
+        default='SCENE'
+    )
  
 class PsxBoneExportMixin:
     bone_filter_mode: EnumProperty(
@@ -148,11 +179,6 @@ class PsxBoneExportMixin:
     )
     bone_collection_list: CollectionProperty(type=PSX_PG_bone_collection_list_item)
     bone_collection_list_index: IntProperty(default=0, name='', description='')
-    root_bone_name: StringProperty(
-        name='Root Bone Name',
-        description='The name of the root bone when exporting a PSK with either no armature or multiple armatures',
-        default='ROOT',
-    )
 
 
 class PSX_PG_scene_export(PropertyGroup, TransformMixin):

io_scene_psk_psa/shared/types.pyi

@@ -0,0 +1,62 @@
+from typing import Generic, TypeVar, Iterable, Sized
+
+T = TypeVar("T")
+
+# https://docs.blender.org/api/current/bpy.types.bpy_prop_collection_idprop.html#bpy.types.bpy_prop_collection_idprop
+class BpyCollectionProperty(Generic[T], Iterable[T], Sized):
+    def add(self) -> T:
+        pass
+
+    def clear(self) -> None:
+        pass
+
+    def move(self, src_index: int, dst_index: int):
+        pass
+
+    def remove(self, index: int):
+        pass
+
+
+class PSX_PG_bone_collection_list_item:
+    armature_object_name: str
+    armature_data_name: str
+    name: str
+    index: int
+    count: int
+    is_selected: bool
+
+
+class PSX_PG_action_export:
+    group: str
+    compression_ratio: float
+    key_quota: int
+    fps: float
+
+
+class AxisMixin:
+    forward_axis: str
+    up_axis: str
+
+
+class TransformMixin(AxisMixin):
+    scale: float
+
+
+class ExportSpaceMixin:
+    export_space: str
+
+
+class TransformSourceMixin:
+    transform_source: str
+
+
+class PsxBoneExportMixin:
+    bone_filter_mode: str
+    bone_collection_list: BpyCollectionProperty[PSX_PG_bone_collection_list_item]
+    bone_collection_list_index: int
+
+
+class PSX_PG_scene_export(TransformSourceMixin):
+    pass
+
+bone_filter_mode_items: tuple[tuple[str, str, str]]

tests/psa_import_test.py

@@ -37,3 +37,29 @@ def test_psa_import_all():
     EXPECTED_ACTION_COUNT = 135
     assert len(bpy.data.actions) == EXPECTED_ACTION_COUNT, \
         f"Expected {EXPECTED_ACTION_COUNT} actions, but found {len(bpy.data.actions)}."
+
+
+def test_psa_import_convert_to_samples():
+    assert bpy.ops.psk.import_file(
+        filepath=SHREK_PSK_FILEPATH,
+        components='ALL',
+        ) == {'FINISHED'}, "PSK import failed."
+
+    armature_object = bpy.data.objects.get('Shrek', None)
+    assert armature_object is not None, "Armature object not found in the scene."
+    assert armature_object.type == 'ARMATURE', "Object is not of type ARMATURE."
+
+    # Select the armature object
+    bpy.context.view_layer.objects.active = armature_object
+    armature_object.select_set(True)
+
+    # Import the associated PSA file with import_all operator, and convert to samples.
+    assert bpy.ops.psa.import_all(
+        filepath=SHREK_PSA_FILEPATH,
+        should_convert_to_samples=True
+        ) == {'FINISHED'}, "PSA import failed."
+    
+    # TODO: More thorough tests on the imported data for the animations.
+    EXPECTED_ACTION_COUNT = 135
+    assert len(bpy.data.actions) == EXPECTED_ACTION_COUNT, \
+        f"Expected {EXPECTED_ACTION_COUNT} actions, but found {len(bpy.data.actions)}."

tests/psk_export_test.py

@@ -0,0 +1,62 @@
+import bpy
+import pytest
+import tempfile
+from psk_psa_py.psk.reader import read_psk_from_file
+
+
+@pytest.fixture(autouse=True)
+def run_before_and_after_tests(tmpdir):
+    # Setup: Run before the tests
+    bpy.ops.wm.read_homefile(filepath='tests/data/psk_export_tests.blend')
+
+    yield
+    # Teardown: Run after the tests
+    pass
+
+
+def export_psk_and_read_back(collection_name: str):
+    collection = bpy.data.collections.get(collection_name, None)
+    assert collection is not None, f"Collection {collection_name} not found in the scene."
+
+    # Select the collection to make it the active collection.
+    view_layer = bpy.context.view_layer
+    assert view_layer is not None, "No active view layer found."
+    view_layer.active_layer_collection = view_layer.layer_collection.children[collection_name]
+
+    filepath = str(tempfile.gettempdir() + f'/{collection_name}.psk')
+
+    collection.exporters[0].filepath = filepath
+
+    assert bpy.ops.collection.exporter_export() == {'FINISHED'}, "PSK export failed."
+
+    # Now load the exported PSK file and return its contents.
+    psk = read_psk_from_file(filepath)
+    return psk
+
+
+def test_psk_export_cube_no_bones():
+    psk = export_psk_and_read_back('cube_no_bones')
+
+    # There should be one bone when no armature is present, this is added automatically to serve as the root bone for the mesh.
+    assert len(psk.bones) == 1, f"Expected 1 bone, but found {len(psk.bones)}."
+    assert len(psk.points) == 8, f"Expected 8 points, but found {len(psk.points)}."
+    assert len(psk.faces) == 12, f"Expected 12 faces, but found {len(psk.faces)}."
+    assert len(psk.materials) == 1, f"Expected 1 material, but found {len(psk.materials)}."
+
+
+def test_cube_edge_split():
+    # The cube has all the edges set to split with a modifier.
+    psk = export_psk_and_read_back('cube_edge_split')
+
+    assert len(psk.bones) == 1, f"Expected 1 bone, but found {len(psk.bones)}."
+    assert len(psk.points) == 24, f"Expected 24 points, but found {len(psk.points)}."
+    assert len(psk.faces) == 12, f"Expected 12 faces, but found {len(psk.faces)}."
+    assert len(psk.materials) == 1, f"Expected 1 material, but found {len(psk.materials)}."
+
+
+def test_cube_with_simple_armature():
+    # The cube has all the edges set to split with a modifier.
+    psk = export_psk_and_read_back('cube_with_simple_armature')
+
+    assert len(psk.bones) == 1, f"Expected 1 bone, but found {len(psk.bones)}."
+    assert psk.bones[0].name == b'ROOT', f"Expected bone name 'ROOT', but found {psk.bones[0].name}."

tests/requirements.txt

@@ -1,3 +1,3 @@
 pytest
 pytest-cov
-psk-psa-py
+psk-psa-py == 0.0.4