blender_shapekey_replicator.py

import bpy
import mathutils

def GetMesh(obj_name):
    obj = bpy.data.objects.get(obj_name)
    if obj is None:
        return None
    return obj.data

def GetShapeKey(mesh, shape_key_name):
    if mesh is None:
        return None
    
    if not mesh.shape_keys:
        return None
    
    shape_keys = mesh.shape_keys.key_blocks
    if shape_key_name not in shape_keys:
        return None
    
    return shape_keys[shape_key_name]

def GetVerticesWithMaterial(mesh, material_name):
    material_index = None
    for i, mat in enumerate(mesh.materials):
        if mat.name == material_name:
            material_index = i
            break
    if material_index is None:
        return []

    vertices = []
    uv_layer = mesh.uv_layers.active
    for poly in mesh.polygons:
        if poly.material_index == material_index:
            for loop_index in poly.loop_indices:
                vertex_index = mesh.loops[loop_index].vertex_index
                uv_coords = uv_layer.data[loop_index].uv
                if vertex_index not in vertices:
                    vertices.append((vertex_index, uv_coords))
    return vertices

def ModifyShapeKeyVertices(source_object_name, source_material_name, target_object_name, target_material_name, shape_key_name, uv_distance_threshold):
    # Get the source mesh and the target mesh
    source_mesh = GetMesh(source_object_name)
    if source_mesh is None:
        print("Source object not found")
        return
    
    target_mesh = GetMesh(target_object_name)
    if target_mesh is None:
        print("Target object not found")
        return
    
    # Get the shape key for the source mesh
    shape_key = GetShapeKey(source_mesh, shape_key_name)
    if shape_key is None:
        print("Shape key not found in source mesh")
        return
    
    # Get the vertices of the source mesh that have the source material
    source_vertices = GetVerticesWithMaterial(source_mesh, source_material_name)
    if len(source_vertices) == 0:
        print("No vertices found with source material")
        return
    
    # Get the vertices of the target mesh that have the target material
    target_vertices = GetVerticesWithMaterial(target_mesh, target_material_name)
    if len(target_vertices) == 0:
        print("No vertices found with target material")
        return
    
    # Create a dictionary mapping UV coordinates of source vertices to vertex indices
    source_uv_dict = {(vertex[1][0], vertex[1][1]): vertex[0] for vertex in source_vertices}
    
    # Iterate through the target vertices and find the closest matching vertex in the source mesh
    for target_vertex in target_vertices:
        target_uv = target_vertex[1]
        closest_uv_distance = float("inf")
        closest_vertex_index = None
        for source_vertex in source_vertices:
            source_uv = source_vertex[1]
            uv_distance = mathutils.Vector(source_uv - target_uv).length_squared
            if uv_distance < closest_uv_distance:
                closest_uv_distance = uv_distance
                closest_vertex_index = source_vertex[0]
        
        # Modify the shape key value for the closest matching vertex if it is within the threshold distance
        if closest_uv_distance < uv_distance_threshold**2 and closest_vertex_index is not None:
            shape_key.data[closest_vertex_index].co = target_mesh.vertices[target_vertex[0]].co

ModifyShapeKeyVertices("MeshObjectA", "MaterialA", "MeshObjectB", "MaterialB", "ShapekeyA", 0.0001)