store vertex offsets between a meshes shape keys in it's UV layers

Author: ibra-kdbra

projects/Blender_tools/mesh_morpher.py

@@ -0,0 +1,154 @@
+bl_info = {
+    "name": "Mesh Morpher",
+    "author": "ibra-kdbra",
+    "version": (1, 0),
+    "blender": (4, 0, 1),
+    "location": "View3D > Sidebar > Unreal Tools Tab",
+    "description": "A tool for storing shape key data for use in a vertex shader.",
+    "warning": "",
+    "doc_url": "",
+    "category": "Unreal Tools",
+}
+
+
+import bpy
+
+
+def pack_normals(me):
+    """Stores normals in a given mesh's vertex colors"""
+    if not me.vertex_colors:
+        me.vertex_colors.new()
+    col = me.vertex_colors[0]
+    col.name = "normals"
+    key = me.shape_keys.key_blocks[1]
+    normals = list(zip(*[iter(key.normals_vertex_get())]*3))
+    for loop in me.loops:
+        r, g, b = normals[loop.vertex_index]
+        col.data[loop.index].color = ((r + 1) * 0.5, (-g + 1) * 0.5, (b + 1) * 0.5, 1)
+
+
+def get_shape_key_offsets(shape_keys, two_shape_keys=False):
+    """Return a list of vertex offsets between shape keys"""
+    keys = shape_keys.key_blocks
+    offsets = []
+    original = keys[0].data
+    target = keys[1].data
+    offset = [v1.co - v2.co for v1, v2 in zip(target, original)]
+    offsets.append(offset)
+    if two_shape_keys:
+        target = keys[2].data
+        offset = [v1.co - v2.co for v1, v2 in zip(target, original)]
+        offsets.append(offset)
+    return offsets
+
+
+def pack_offsets(ob, offsets):
+    """Stores shape key vertex offsets in mesh's UVs"""
+    me = ob.data
+    while len(me.uv_layers) < 4:
+        me.uv_layers.new()
+    for loop in me.loops:
+        x1, y1, z1 = offsets[0][loop.vertex_index]
+        if len(offsets) > 1:
+            offset = offsets[1][loop.vertex_index]
+        else:
+            offset = ob.location
+        x2, y2, z2 = offset
+        me.uv_layers[1].data[loop.index].uv = (x2, 1 - (-y2))
+        me.uv_layers[2].data[loop.index].uv = (z2, 1 - x1)
+        me.uv_layers[3].data[loop.index].uv = (-y1, 1 - z1)
+
+
+class MeshMorpherSettings(bpy.types.PropertyGroup):
+    store_shape_key1_normals: bpy.props.BoolProperty(
+        name="First Shape Key Normals",
+        description="Store first shape key's vertex normals in vertex colors",
+        default=True
+    )
+    two_shape_keys: bpy.props.BoolProperty(
+        name="Two Shape Keys",
+        description="Store vertex offsets for first and second shape keys",
+        default=False
+    )
+
+
+class OBJECT_OT_ProcessShapeKeys(bpy.types.Operator):
+    """Store object's shape key offsets in it's UV layers"""
+    bl_idname = "object.process_shape_keys"
+    bl_label = "Process Shape Keys"
+
+    store_shape_key1_normals: bpy.props.BoolProperty(
+        name="First Shape Key Normals",
+        default=True
+    )
+    two_shape_keys: bpy.props.BoolProperty(
+        name="Two Shape Keys",
+        default=False
+    )
+
+    @classmethod
+    def poll(cls, context):
+        ob = context.active_object
+        return ob and ob.type == 'MESH' and ob.mode == 'OBJECT'
+
+
+    def execute(self, context):
+        units = context.scene.unit_settings
+        ob = context.object
+        shape_keys = ob.data.shape_keys
+        if units.system != 'METRIC' or round(units.scale_length, 2) != 0.01:
+            self.report(
+                {'ERROR'},
+                "Scene Units must be Metric with a Unit Scale of 0.01!"
+            )
+            return {'CANCELLED'}
+        if not shape_keys:
+            self.report({'ERROR'}, "Object has no shape keys!")
+            return {'CANCELLED'}
+        if len(shape_keys.key_blocks) < 2 + self.two_shape_keys:
+            self.report({'ERROR'}, "Object needs additional shape keys!")
+            return {'CANCELLED'}
+        if self.store_shape_key1_normals:
+            pack_normals(ob.data)
+        offsets = get_shape_key_offsets(shape_keys, self.two_shape_keys)
+        pack_offsets(ob, offsets)
+        return {'FINISHED'}
+
+
+class VIEW3D_PT_MeshMorpher(bpy.types.Panel):
+    """Creates a Panel in 3D Viewport"""
+    bl_label = "Mesh Morpher"
+    bl_idname = "VIEW3D_PT_mesh_morpher"
+    bl_space_type = 'VIEW_3D'
+    bl_region_type = 'UI'
+    bl_category = "Unreal Tools"
+
+    def draw(self, context):
+        layout = self.layout
+        col = layout.column()
+        props = context.scene.mesh_morpher_settings
+        col.prop(props, "store_shape_key1_normals")
+        col.prop(props, "two_shape_keys")
+        op = col.operator("object.process_shape_keys")
+        op.store_shape_key1_normals = props.store_shape_key1_normals
+        op.two_shape_keys = props.two_shape_keys
+
+
+def register():
+    bpy.utils.register_class(MeshMorpherSettings)
+    bpy.utils.register_class(OBJECT_OT_ProcessShapeKeys)
+    bpy.utils.register_class(VIEW3D_PT_MeshMorpher)
+    bpy.types.Scene.mesh_morpher_settings = bpy.props.PointerProperty(
+        type=MeshMorpherSettings
+    )
+
+
+def unregister():
+    bpy.utils.unregister_class(MeshMorpherSettings)
+    bpy.utils.unregister_class(OBJECT_OT_ProcessShapeKeys)
+    bpy.utils.unregister_class(VIEW3D_PT_MeshMorpher)
+    del bpy.types.Scene.mesh_morpher_settings
+
+
+if __name__ == "__main__":
+    register()