Replace pymeshlab with trimesh in inference_triposg.py (no py3.13 wheels)

pymeshlab has no Python 3.13 wheels. It's only used for simplify_mesh()
which does QEM decimation + vertex merging. Replace with trimesh's
simplify_quadric_decimation() (backed by fast-simplification package).
Patch applied at runtime after triposg clone, guarded by pymeshlab_replaced_v1 tag.

app.py

@@ -469,6 +469,54 @@ def load_triposg():
             _iu_path.write_text(_iu_text)
             print("[load_triposg] Patched inference_utils.py: diso optional + queries dtype cast")
 
+    # Patch inference_triposg.py: replace pymeshlab (no py3.13 wheels) with trimesh.
+    # pymeshlab is only used for simplify_mesh() — QEM decimation + vertex merging.
+    # trimesh.simplify_quadric_decimation() is a direct equivalent (needs fast-simplification).
+    _it_path = triposg_src / "scripts" / "inference_triposg.py"
+    if _it_path.exists():
+        _it_text = _it_path.read_text()
+        if "pymeshlab_replaced_v1" not in _it_text:
+            # Remove the pymeshlab import
+            _it_text = _it_text.replace("import pymeshlab\n", "")
+            # Replace the three pymeshlab helper functions + simplify_mesh with trimesh version
+            _old_simplify = (
+                "def mesh_to_pymesh(vertices, faces):\n"
+                "    mesh = pymeshlab.Mesh(vertex_matrix=vertices, face_matrix=faces)\n"
+                "    ms = pymeshlab.MeshSet()\n"
+                "    ms.add_mesh(mesh)\n"
+                "    return ms\n"
+                "\n"
+                "\n"
+                "def pymesh_to_trimesh(mesh):\n"
+                "    verts = mesh.vertex_matrix()\n"
+                "    faces = mesh.face_matrix()\n"
+                "    return trimesh.Trimesh(vertices=verts, faces=faces)\n"
+                "\n"
+                "\n"
+                "def simplify_mesh(mesh: trimesh.Trimesh, n_faces):\n"
+                "    if mesh.faces.shape[0] > n_faces:\n"
+                "        ms = mesh_to_pymesh(mesh.vertices, mesh.faces)\n"
+                "        ms.meshing_merge_close_vertices()\n"
+                "        ms.meshing_decimation_quadric_edge_collapse(targetfacenum = n_faces)\n"
+                "        return pymesh_to_trimesh(ms.current_mesh())\n"
+                "    else:\n"
+                "        return mesh\n"
+            )
+            _new_simplify = (
+                "# pymeshlab_replaced_v1: replaced with trimesh (no py3.13 wheels for pymeshlab)\n"
+                "def simplify_mesh(mesh: trimesh.Trimesh, n_faces):\n"
+                "    if mesh.faces.shape[0] > n_faces:\n"
+                "        mesh = trimesh.Trimesh(vertices=mesh.vertices, faces=mesh.faces, process=True)\n"
+                "        mesh = mesh.simplify_quadric_decimation(n_faces)\n"
+                "    return mesh\n"
+            )
+            if _old_simplify in _it_text:
+                _it_text = _it_text.replace(_old_simplify, _new_simplify)
+                _it_path.write_text(_it_text)
+                print("[load_triposg] Patched inference_triposg.py: pymeshlab → trimesh simplify")
+            else:
+                print("[load_triposg] WARNING: could not patch inference_triposg.py (pattern not found)")
+
     weights_path = snapshot_download("VAST-AI/TripoSG")
 
     from triposg.pipelines.pipeline_triposg import TripoSGPipeline

requirements.txt

@@ -28,6 +28,7 @@ xformers
 
 # 3D / Mesh
 trimesh
+fast-simplification
 # open3d: no Python 3.13 wheels — not used in this Space
 # pymeshlab: no Python 3.13 wheels — not used in this Space
 pygltflib