Added sampling mode and changed the default sampling mode to be "Interpolated" rather than "Subframe"

io_scene_psk_psa/psa/builder.py

@@ -1,6 +1,7 @@
 from typing import Optional
 
 from bpy.types import Bone, Action, PoseBone
+from mathutils import Vector
 
 from .data import *
 from ..shared.helpers import *
@@ -33,6 +34,7 @@ class PsaBuildOptions:
         self.sequence_name_suffix: str = ''
         self.root_motion: bool = False
         self.scale = 1.0
+        self.sampling_mode: str = 'INTERPOLATED'  # One of ('INTERPOLATED', 'SUBFRAME')
 
 
 def _get_pose_bone_location_and_rotation(pose_bone: PoseBone, armature_object: Object, options: PsaBuildOptions):
@@ -184,12 +186,7 @@ def build_psa(context: bpy.types.Context, options: PsaBuildOptions) -> Psa:
 
         frame = float(frame_start)
 
-        for _ in range(frame_count):
+        def add_key(location: Vector, rotation: Quaternion):
-            context.scene.frame_set(frame=int(frame), subframe=frame % 1.0)
-
-            for pose_bone in pose_bones:
-                location, rotation = _get_pose_bone_location_and_rotation(pose_bone, export_sequence.armature_object, options)
-
             key = Psa.Key()
             key.location.x = location.x
             key.location.y = location.y
@@ -201,6 +198,70 @@ def build_psa(context: bpy.types.Context, options: PsaBuildOptions) -> Psa:
             key.time = 1.0 / psa_sequence.fps
             psa.keys.append(key)
 
+        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]] = []
+
+                next_frame: Optional[int] = None
+                next_frame_bone_poses: List[Tuple[Vector, Quaternion]] = []
+
+                for _ in range(frame_count):
+                    if last_frame is None or last_frame != int(frame):
+                        # Populate the bone poses for frame A.
+                        last_frame = int(frame)
+
+                        # TODO: simplify this code and make it easier to follow!
+                        if next_frame == last_frame:
+                            # Simply transfer the data from next_frame to the last_frame so that we don't need to
+                            # resample anything.
+                            last_frame_bone_poses = next_frame_bone_poses.copy()
+                        else:
+                            last_frame_bone_poses.clear()
+                            context.scene.frame_set(frame=last_frame)
+                            for pose_bone in pose_bones:
+                                location, rotation = _get_pose_bone_location_and_rotation(pose_bone,
+                                                                                          export_sequence.armature_object,
+                                                                                          options)
+                                last_frame_bone_poses.append((location, rotation))
+
+                        next_frame = None
+                        next_frame_bone_poses.clear()
+
+                    # If this is not a subframe, just use the last frame's bone poses.
+                    if frame % 1.0 == 0:
+                        for i in range(len(pose_bones)):
+                            add_key(*last_frame_bone_poses[i])
+                    else:
+                        # Otherwise, this is a subframe, so we need to interpolate the pose between the next frame and the last frame.
+                        if next_frame is None:
+                            next_frame = last_frame + 1
+                            context.scene.frame_set(frame=next_frame)
+                            for pose_bone in pose_bones:
+                                location, rotation = _get_pose_bone_location_and_rotation(pose_bone, export_sequence.armature_object, options)
+                                next_frame_bone_poses.append((location, rotation))
+
+                        factor = frame % 1.0
+
+                        for i in range(len(pose_bones)):
+                            last_location, last_rotation = last_frame_bone_poses[i]
+                            next_location, next_rotation = next_frame_bone_poses[i]
+
+                            location = last_location.lerp(next_location, factor)
+                            rotation = last_rotation.slerp(next_rotation, factor)
+
+                            add_key(location, rotation)
+
+                    frame += frame_step
+            case 'SUBFRAME':
+                for _ in range(frame_count):
+                    context.scene.frame_set(frame=int(frame), subframe=frame % 1.0)
+
+                    for pose_bone in pose_bones:
+                        location, rotation = _get_pose_bone_location_and_rotation(pose_bone, export_sequence.armature_object, options)
+                        add_key(location, rotation)
+
                     frame += frame_step
 
         frame_start_index += frame_count

io_scene_psk_psa/psa/export/operators.py

@@ -314,13 +314,16 @@ class PSA_OT_export(Operator, ExportHelper):
                         layout.label(text=f'Duplicate action: {action_name}', icon='ERROR')
                         break
 
-            data_source_header, data_source_panel = layout.panel('Data Source', default_closed=False)
+            sampling_header, sampling_panel = layout.panel('Data Source', default_closed=False)
-            data_source_header.label(text='Data Sources')
+            sampling_header.label(text='Sampling')
-            if data_source_panel:
+            if sampling_panel:
-                flow = data_source_panel.grid_flow()
+                flow = sampling_panel.grid_flow()
                 flow.use_property_split = True
                 flow.use_property_decorate = False
 
+                # SAMPLING MODE
+                flow.prop(pg, 'sampling_mode', text='Sampling Mode')
+
                 # FPS
                 col = flow.row(align=True)
                 col.prop(pg, 'fps_source', text='FPS')
@@ -378,6 +381,9 @@ class PSA_OT_export(Operator, ExportHelper):
                                    f'\The armature data block for "{obj.name}\" (\'{obj.data.name}\') does not match '
                                    f'the active armature data block (\'{context.view_layer.objects.active.name}\')')
 
+        if context.scene.is_nla_tweakmode:
+            raise RuntimeError('Cannot export PSA while in NLA tweak mode')
+
     def invoke(self, context, _event):
         try:
             self._check_context(context)
@@ -482,6 +488,7 @@ class PSA_OT_export(Operator, ExportHelper):
         options.sequence_name_suffix = pg.sequence_name_suffix
         options.root_motion = pg.root_motion
         options.scale = pg.scale
+        options.sampling_mode = pg.sampling_mode
 
         try:
             psa = build_psa(context, options)

io_scene_psk_psa/psa/export/properties.py

@@ -217,6 +217,16 @@ class PSA_PG_export(PropertyGroup):
         min=0.0,
         soft_max=100.0
     )
+    sampling_mode: EnumProperty(
+        name='Sampling Mode',
+        options=empty_set,
+        description='The method by which frames are sampled',
+        items=(
+            ('INTERPOLATED', 'Interpolated', 'Sampling is performed by interpolating the evaluated bone poses from the adjacent whole frames.', 'INTERPOLATED', 0),
+            ('SUBFRAME', 'Subframe', 'Sampling is performed by evaluating the bone poses at the subframe time.\n\nNot recommended unless you are also animating with subframes enabled.', 'SUBFRAME', 1),
+        ),
+        default='INTERPOLATED'
+    )
 
 
 def filter_sequences(pg: PSA_PG_export, sequences) -> List[int]: