Reduce boilerplate for mesh mangling addons

Makes it less annoying to compose separate addons with different manglers

addon_examples/local_mesh.py

@@ -280,4 +280,23 @@ class MeshUploadInterceptingAddon(BaseAddon):
                 cls._replace_local_mesh(session.main_region, asset_repo, mesh_list)
 
 
+class BaseMeshManglerAddon(BaseAddon):
+    """Base class for addons that mangle uploaded or local mesh"""
+    MESH_MANGLERS: List[Callable[[MeshAsset], MeshAsset]]
+
+    def handle_init(self, session_manager: SessionManager):
+        # Add our manglers into the list
+        MeshUploadInterceptingAddon.mesh_manglers.extend(self.MESH_MANGLERS)
+        # Tell the local mesh plugin that the mangler list changed, and to re-apply
+        MeshUploadInterceptingAddon.remangle_local_mesh(session_manager)
+
+    def handle_unload(self, session_manager: SessionManager):
+        # Clean up our manglers before we go away
+        mangler_list = MeshUploadInterceptingAddon.mesh_manglers
+        for mangler in self.MESH_MANGLERS:
+            if mangler in mangler_list:
+                mangler_list.remove(mangler)
+        MeshUploadInterceptingAddon.remangle_local_mesh(session_manager)
+
+
 addons = [MeshUploadInterceptingAddon()]

addon_examples/mesh_mangler.py

@@ -11,8 +11,6 @@ to add to give a mesh an arbitrary center of rotation / scaling.
 
 from hippolyzer.lib.base.mesh import MeshAsset
 from hippolyzer.lib.proxy.addons import AddonManager
-from hippolyzer.lib.proxy.addon_utils import BaseAddon
-from hippolyzer.lib.proxy.sessions import SessionManager
 
 import local_mesh
 AddonManager.hot_reload(local_mesh, require_addons_loaded=True)
@@ -37,6 +35,9 @@ def reorient_mesh(orientation):
     # X=1, Y=2, Z=3
     def _reorienter(mesh: MeshAsset):
         for material in mesh.iter_lod_materials():
+            if "Position" not in material:
+                # Must be a NoGeometry LOD
+                continue
             # We don't need to use positions_(to/from)_domain here since we're just naively
             # flipping the axes around.
             material["Position"] = _reorient_coord_list(material["Position"], orientation)
@@ -46,28 +47,11 @@ def reorient_mesh(orientation):
     return _reorienter
 
 
-OUR_MANGLERS = [
-    # Negate the X and Y axes on any mesh we upload or create temp
-    reorient_mesh((-1, -2, 3)),
-]
+class ExampleMeshManglerAddon(local_mesh.BaseMeshManglerAddon):
+    MESH_MANGLERS = [
+        # Negate the X and Y axes on any mesh we upload or create temp
+        reorient_mesh((-1, -2, 3)),
+    ]
 
 
-class MeshManglerExampleAddon(BaseAddon):
-    def handle_init(self, session_manager: SessionManager):
-        # Add our manglers into the list
-        local_mesh_addon = local_mesh.MeshUploadInterceptingAddon
-        local_mesh_addon.mesh_manglers.extend(OUR_MANGLERS)
-        # Tell the local mesh plugin that the mangler list changed, and to re-apply
-        local_mesh_addon.remangle_local_mesh(session_manager)
-
-    def handle_unload(self, session_manager: SessionManager):
-        # Clean up our manglers before we go away
-        local_mesh_addon = local_mesh.MeshUploadInterceptingAddon
-        mangler_list = local_mesh_addon.mesh_manglers
-        for mangler in OUR_MANGLERS:
-            if mangler in mangler_list:
-                mangler_list.remove(mangler)
-        local_mesh_addon.remangle_local_mesh(session_manager)
-
-
-addons = [MeshManglerExampleAddon()]
+addons = [ExampleMeshManglerAddon()]