Added support for exporting multiple UV layers.

README.md

@@ -3,3 +3,6 @@
 This is a Blender addon allowing you to export static meshes to the now-defunct ASE (ASCII Scene Export) format still in use in legacy programs like Unreal Tournament 2004.
 
 Check out [this video](https://www.youtube.com/watch?v=gpmBxCGHQjU) on how to install and use the addon.
+
+Resources:
+* https://wiki.beyondunreal.com/Legacy:ASE_File_Format

src/__init__.py

@@ -2,7 +2,7 @@ bl_info = {
     'name': 'ASCII Scene Export',
     'description': 'Export ASE (ASCII Scene Export) files',
     'author': 'Colin Basnett (Darklight Games)',
-    'version': (1, 0, 2),
+    'version': (1, 1, 0),
     'blender': (2, 90, 0),
     'location': 'File > Import-Export',
     'warning': 'This add-on is under development.',

src/ase.py

@@ -26,11 +26,16 @@ def is_collision_name(name):
     return name.startswith('MCDCX_')
 
 
+class ASEUVLayer(object):
+    def __init__(self):
+        self.texture_vertices = []
+
+
 class ASEGeometryObject(object):
     def __init__(self):
         self.name = ''
         self.vertices = []
-        self.texture_vertices = []
+        self.uv_layers = []
         self.faces = []
         self.texture_vertex_faces = []
         self.face_normals = []

src/builder.py

@@ -37,7 +37,6 @@ class ASEBuilder(object):
             if not geometry_object.is_collision and len(mesh_data.materials) == 0:
                 raise ASEBuilderError(f'Mesh \'{obj.name}\' must have at least one material')
 
-            geometry_object.vertex_offset += len(geometry_object.vertices)
             vertex_transform = Matrix.Scale(options.scale, 4) @ Matrix.Rotation(math.pi, 4, 'Z') @ obj.matrix_world
             for vertex_index, vertex in enumerate(mesh_data.vertices):
                 geometry_object.vertices.append(vertex_transform @ vertex.co)
@@ -69,6 +68,11 @@ class ASEBuilder(object):
                     face.material_index = material_indices[loop_triangle.material_index]
                 # The UT2K4 importer only accepts 32 smoothing groups. Anything past this completely mangles the
                 # smoothing groups and effectively makes the whole model use sharp-edge rendering.
+                # The fix is to constrain the smoothing group between 0 and 31 by applying a modulo of 32 to the actual
+                # smoothing group index.
+                # This may result in bad calculated normals on export in rare cases. For example, if a face with a
+                # smoothing group of 3 is adjacent to a face with a smoothing group of 35 (35 % 32 == 3), those faces
+                # will be treated as part of the same smoothing group.
                 face.smoothing = (poly_groups[loop_triangle.polygon_index] - 1) % 32
                 geometry_object.faces.append(face)
 
@@ -85,14 +89,15 @@ class ASEBuilder(object):
                         face_normal.vertex_normals.append(vertex_normal)
                     geometry_object.face_normals.append(face_normal)
 
-            uv_layer = mesh_data.uv_layers.active.data
-
-            # Texture Coordinates
-            geometry_object.texture_vertex_offset += len(geometry_object.texture_vertices)
             if not geometry_object.is_collision:
+                # Texture Coordinates
+                for i, uv_layer_data in enumerate([x.data for x in mesh_data.uv_layers]):
+                    if i >= len(geometry_object.uv_layers):
+                        geometry_object.uv_layers.append(ASEUVLayer())
+                    uv_layer = geometry_object.uv_layers[i]
                     for loop_index, loop in enumerate(mesh_data.loops):
-                    u, v = uv_layer[loop_index].uv
+                        u, v = uv_layer_data[loop_index].uv
-                    geometry_object.texture_vertices.append((u, v, 0.0))
+                        uv_layer.texture_vertices.append((u, v, 0.0))
 
             # Texture Faces
             if not geometry_object.is_collision:
@@ -103,6 +108,10 @@ class ASEBuilder(object):
                         geometry_object.texture_vertex_offset + loop_triangle.loops[2]
                     ))
 
+            # Update data offsets for next iteration
+            geometry_object.texture_vertex_offset = len(mesh_data.loops)
+            geometry_object.vertex_offset = len(geometry_object.vertices)
+
         if len(ase.geometry_objects) == 0:
             raise ASEBuilderError('At least one mesh object must be selected')
 

src/writer.py

@@ -146,18 +146,20 @@ class ASEWriter(object):
                 face_node.push_sub_command('MESH_MTLID').push_datum(face.material_index)
 
             # Texture Coordinates
-            if len(geometry_object.texture_vertices) > 0:
+            for i, uv_layer in enumerate(geometry_object.uv_layers):
-                mesh_node.push_child('MESH_NUMTVERTEX').push_datum(len(geometry_object.texture_vertices))
+                parent_node = mesh_node if i == 0 else mesh_node.push_child('MESH_MAPPINGCHANNEL')
-                tvertlist_node = mesh_node.push_child('MESH_TVERTLIST')
+                if i > 0:
-                for tvert_index, tvert in enumerate(geometry_object.texture_vertices):
+                    parent_node.push_datum(i + 1)
+                parent_node.push_child('MESH_NUMTVERTEX').push_datum(len(uv_layer.texture_vertices))
+                tvertlist_node = parent_node.push_child('MESH_TVERTLIST')
+                for tvert_index, tvert in enumerate(uv_layer.texture_vertices):
                     tvert_node = tvertlist_node.push_child('MESH_TVERT')
                     tvert_node.push_datum(tvert_index)
                     tvert_node.push_data(list(tvert))
-
                 # Texture Faces
                 if len(geometry_object.texture_vertex_faces) > 0:
-                mesh_node.push_child('MESH_NUMTVFACES').push_datum(len(geometry_object.texture_vertex_faces))
+                    parent_node.push_child('MESH_NUMTVFACES').push_datum(len(geometry_object.texture_vertex_faces))
-                texture_faces_node = mesh_node.push_child('MESH_TFACELIST')
+                    texture_faces_node = parent_node.push_child('MESH_TFACELIST')
                     for texture_face_index, texture_face in enumerate(geometry_object.texture_vertex_faces):
                         texture_face_node = texture_faces_node.push_child('MESH_TFACE')
                         texture_face_node.push_data([texture_face_index] + list(texture_face))