USD-Exporting improvements

newton/_src/viewer/viewer.py

@@ -380,6 +380,7 @@ def log_mesh(
         uvs: wp.array = None,
         hidden=False,
         backface_culling=True,
+        face_varying_uv=False,
     ):
         pass
 

newton/_src/viewer/viewer_file.py

@@ -99,6 +99,7 @@ def log_mesh(
         uvs: wp.array = None,
         hidden=False,
         backface_culling=True,
+        face_varying_uv=False,
     ):
         """File viewer doesn't render meshes, so this is a no-op."""
         pass

newton/_src/viewer/viewer_gl.py

@@ -200,6 +200,7 @@ def log_mesh(
         uvs: wp.array = None,
         hidden=False,
         backface_culling=True,
+        face_varying_uv=False,
     ):
         """
         Log a mesh for rendering.
@@ -212,6 +213,7 @@ def log_mesh(
             uvs (wp.array, optional): Vertex UVs.
             hidden (bool): Whether the mesh is hidden.
             backface_culling (bool): Enable backface culling.
+            face_varying_uv (bool): Enable face varying UV.
         """
         assert isinstance(points, wp.array)
         assert isinstance(indices, wp.array)

newton/_src/viewer/viewer_null.py

@@ -50,6 +50,7 @@ def log_mesh(
         uvs: wp.array = None,
         hidden=False,
         backface_culling=True,
+        face_varying_uv=False,
     ):
         """
         No-op implementation for logging a mesh.
@@ -62,6 +63,7 @@ def log_mesh(
             uvs: Texture coordinates (optional).
             hidden: Whether the mesh is hidden.
             backface_culling: Whether to enable backface culling.
+            face_varying_uv: Enable face varying UV (default: vertex varying).
         """
         pass
 

newton/_src/viewer/viewer_rerun.py

@@ -87,6 +87,7 @@ def log_mesh(
         uvs: wp.array = None,
         hidden=False,
         backface_culling=True,
+        face_varying_uv=False,
     ):
         """
         Log a mesh to rerun for visualization.
@@ -97,8 +98,10 @@ def log_mesh(
             indices (wp.array): Triangle indices (wp.uint32).
             normals (wp.array, optional): Vertex normals (wp.vec3).
             uvs (wp.array, optional): UV coordinates (wp.vec2).
+            uv_indices (wp.array, optional): Triangle indices (wp.uint32) for UVs
             hidden (bool): Whether the mesh is hidden (unused).
             backface_culling (bool): Whether to enable backface culling (unused).
+            face_varying_uv (bool): Whether to enable face varying UV (default: vertex varying).
         """
         assert isinstance(points, wp.array)
         assert isinstance(indices, wp.array)

newton/_src/viewer/viewer_usd.py

@@ -62,7 +62,8 @@ def __init__(self, output_path, fps=60, up_axis="Z", num_frames=None):
 
         # Create USD stage
         self.stage = Usd.Stage.CreateNew(output_path)
-        self.stage.SetFramesPerSecond(fps)
+        self.stage.SetTimeCodesPerSecond(fps)  # number of timeCodes per second for data storage
+        self.stage.SetFramesPerSecond(fps)  # display frame rate (timeline FPS in DCC tools)
         self.stage.SetStartTimeCode(0)
 
         UsdGeom.SetStageUpAxis(self.stage, UsdGeom.Tokens.z)
@@ -133,6 +134,7 @@ def log_mesh(
         uvs: wp.array = None,
         hidden=False,
         backface_culling=True,
+        face_varying_uv=False,
     ):
         """
         Create a USD mesh prototype from vertex and index data.
@@ -145,7 +147,7 @@ def log_mesh(
             uvs (wp.array, optional): UV coordinates as a warp array of wp.vec2.
             hidden (bool, optional): If True, mesh will be hidden. Default is False.
             backface_culling (bool, optional): If True, enable backface culling. Default is True.
-
+            face_varying_uv (bool, optional): If True, enable face varying UV. Default is False (vertex varying).
         Returns:
             str: The mesh prototype path.
         """
@@ -164,6 +166,25 @@ def log_mesh(
             mesh_prim.GetFaceVertexCountsAttr().Set(face_vertex_counts)
             mesh_prim.GetFaceVertexIndicesAttr().Set(indices_np)
 
+            # Set UVs if provided (do not set every frame)
+            if uvs is not None:
+                primvars_api = UsdGeom.PrimvarsAPI(mesh_prim)
+
+                # Get or create the 'st' primvar
+                if not primvars_api.GetPrimvar("st"):
+                    st = primvars_api.CreatePrimvar("st", Sdf.ValueTypeNames.TexCoord2fArray, UsdGeom.Tokens.vertex)
+                else:
+                    st = primvars_api.GetPrimvar("st")
+
+                st.Set(uvs.numpy().astype(np.float32))
+
+                if face_varying_uv:
+                    assert len(uvs) == len(indices_np)
+                    st.SetInterpolation(UsdGeom.Tokens.faceVarying)
+                else:
+                    assert len(uvs) == len(points_np)
+                    st.SetInterpolation(UsdGeom.Tokens.vertex)
+
             # Store the prototype path
             self._meshes[name] = mesh_prim
 
@@ -176,11 +197,6 @@ def log_mesh(
             mesh_prim.GetNormalsAttr().Set(normals_np, self._frame_index)
             mesh_prim.SetNormalsInterpolation(UsdGeom.Tokens.vertex)
 
-        # Set UVs if provided (simplified for now)
-        if uvs is not None:
-            # TODO: Implement UV support for USD meshes
-            pass
-
         # how to hide the prototype mesh but not the instances in USD?
         # mesh_prim.GetVisibilityAttr().Set("inherited" if not hidden else "invisible", self._frame_index)