fix: MToon1 migration doesn't work for 2.16.3 or earlier

src/io_scene_vrm/editor/mtoon1/migration.py

@@ -1,17 +1,73 @@
-from bpy.types import Context
+from bpy.types import Context, NodeReroute, ShaderNodeGroup
+from idprop.types import IDPropertyGroup
 
+from ...common import convert
 from .property_group import reset_shader_node_group
 
 
 def migrate(context: Context) -> None:
     for material in context.blend_data.materials:
         if not material:
             continue
+        if not material.use_nodes:
+            continue
+        if not material.node_tree:
+            continue
+
+        vrm_addon_extension = material.get("vrm_addon_extension")
+        if not isinstance(vrm_addon_extension, IDPropertyGroup):
+            continue
+
+        mtoon1 = vrm_addon_extension.get("mtoon1")
+        if not isinstance(mtoon1, IDPropertyGroup):
+            continue
+
+        if not mtoon1.get("enabled"):
+            continue
+
+        extensions = mtoon1.get("extensions")
+        if not isinstance(extensions, IDPropertyGroup):
+            continue
 
-        if not material.vrm_addon_extension.mtoon1.enabled:
+        vrmc_materials_mtoon = extensions.get("vrmc_materials_mtoon")
+        if not isinstance(vrmc_materials_mtoon, IDPropertyGroup):
             continue
 
-        if tuple(material.vrm_addon_extension.mtoon1.addon_version) < (2, 20, 8):
+        if vrmc_materials_mtoon.get("is_outline_material"):
+            continue
+
+        addon_version = convert.float3_or(mtoon1.get("addon_version"), (0, 0, 0))
+        if addon_version < (2, 16, 4):
+            # https://github.com/saturday06/VRM-Addon-for-Blender/blob/2_10_0/io_scene_vrm/editor/mtoon1/property_group.py#L1658-L1683
+            surface_node_name = "Mtoon1Material.MaterialOutputSurfaceIn"
+            surface_node = material.node_tree.nodes.get(surface_node_name)
+            if not isinstance(surface_node, NodeReroute):
+                continue
+
+            connected = False
+            surface_socket = surface_node.outputs[0]
+            for link in material.node_tree.links:
+                if (
+                    link.from_socket == surface_socket
+                    and link.to_socket
+                    and link.to_socket.node
+                    and link.to_socket.node.type == "OUTPUT_MATERIAL"
+                ):
+                    connected = True
+                    break
+            if not connected:
+                continue
+        else:
+            # https://github.com/saturday06/VRM-Addon-for-Blender/blob/2_16_4/io_scene_vrm/editor/mtoon1/property_group.py#L1913-L1929
+            group_node = material.node_tree.nodes.get("Mtoon1Material.Mtoon1Output")
+            if not isinstance(group_node, ShaderNodeGroup):
+                continue
+            if not group_node.node_tree:
+                continue
+            if group_node.node_tree.name != "VRM Add-on MToon 1.0 Output Revision 1":
+                continue
+
+        if addon_version < (2, 20, 8):
             reset_shader_node_group(
                 context, material, reset_node_tree=True, overwrite=True
             )