Ensure subdiv_iterations is not set uselessly during procedural updat…

…es (#1931)

* Ensure subdiv_iterations is not set uselessly during procedural updates #1929

(cherry picked from commit 1adc860)

* Add changelog

CHANGELOG.md

@@ -4,7 +4,9 @@
 ## Pending feature release
 
 ## Pending bugfix release
-- [usd#1923](https://github.com/Autodesk/arnold-usd/issues/1923) - Fix instance primvar indices with multiple prototypes
+- [usd#1923](https://github.com/Autodesk/arnold-usd/issues/1923) - Fix instance primvar indices 
+with multiple prototypes
+- [usd#1929](https://github.com/Autodesk/arnold-usd/issues/1929) - Ensure subdiv_iterations is not set uselessly during procedural updates
 
 ## [7.3.2.0] - 2024-05-22
 

libs/common/constant_strings.h

@@ -82,6 +82,8 @@ ASTR2(primvars_arnold, "primvars:arnold");
 ASTR2(primvars_arnold_light, "primvars:arnold:light");
 ASTR2(log_file, "log:file");
 ASTR2(log_verbosity, "log:verbosity");
+ASTR2(primvars_arnold_smoothing, "primvars:arnold:smoothing");
+ASTR2(primvars_arnold_subdiv_iterations, "primvars:arnold:subdiv_iterations");
 ASTR2(primvars_arnold_subdiv_type, "primvars:arnold:subdiv_type");
 ASTR2(primvars_arnold_normalize, "primvars:arnold:normalize");
 ASTR2(renderPassAOVDriver, "HdArnoldRenderPass_aov_driver");

libs/translator/reader/read_geometry.cpp

@@ -255,9 +255,9 @@ AtNode* UsdArnoldReadMesh::Read(const UsdPrim &prim, UsdArnoldReaderContext &con
     staticTime.motionBlur = false;
 
     AtNode *node = context.CreateArnoldNode("polymesh", prim.GetPath().GetText());
-
     ReadMatrix(prim, node, time, context);
-    AiNodeSetBool(node, str::smoothing, true);
+    if (!HasAuthoredAttribute(prim, str::t_primvars_arnold_smoothing))
+        AiNodeSetBool(node, str::smoothing, true);
 
     // Get mesh.
     UsdGeomMesh mesh(prim);
@@ -393,8 +393,10 @@ AtNode* UsdArnoldReadMesh::Read(const UsdPrim &prim, UsdArnoldReaderContext &con
 
     _ReadSidedness(mesh, node, frame);
 
-    // reset subdiv_iterations to 0, it might be set in readArnoldParameter
-    AiNodeSetByte(node, str::subdiv_iterations, 0);
+    // reset subdiv_iterations to 0, unless primvars:arnold:subdiv_iterations is 
+    // explicitely set, in which case it would be applied during readArnoldParameter #1929
+    if (!HasAuthoredAttribute(prim, str::t_primvars_arnold_subdiv_iterations))
+        AiNodeSetByte(node, str::subdiv_iterations, 0);
 
     MeshPrimvarsRemapper primvarsRemapper(meshOrientation);
     ReadPrimvars(prim, node, time, context, &primvarsRemapper);
@@ -661,7 +663,8 @@ AtNode* UsdArnoldReadCube::Read(const UsdPrim &prim, UsdArnoldReaderContext &con
     float frame = time.frame;
     AtNode *node = context.CreateArnoldNode("polymesh", prim.GetPath().GetText());
     ReadMatrix(prim, node, time, context);
-    AiNodeSetBool(node, str::smoothing, false);
+    if (!HasAuthoredAttribute(prim, str::t_primvars_arnold_smoothing))
+        AiNodeSetBool(node, str::smoothing, false);
 
     static const VtIntArray numVerts { 4, 4, 4, 4, 4, 4 };
     static const VtIntArray verts { 0, 1, 2, 3,
@@ -713,7 +716,8 @@ AtNode* UsdArnoldReadSphere::Read(const UsdPrim &prim, UsdArnoldReaderContext &c
     float frame = time.frame;
     AtNode *node = context.CreateArnoldNode("polymesh", prim.GetPath().GetText());
     ReadMatrix(prim, node, time, context);
-    AiNodeSetBool(node, str::smoothing, true);
+    if (!HasAuthoredAttribute(prim, str::t_primvars_arnold_smoothing))
+        AiNodeSetBool(node, str::smoothing, true);
 
     static const VtIntArray numVerts{
         3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 
@@ -882,7 +886,9 @@ AtNode* UsdArnoldReadCylinder::Read(const UsdPrim &prim, UsdArnoldReaderContext
     float frame = time.frame;
     AtNode *node = context.CreateArnoldNode("polymesh", prim.GetPath().GetText());
     ReadMatrix(prim, node, time, context);
-    AiNodeSetBool(node, str::smoothing, true);
+    if (!HasAuthoredAttribute(prim, str::t_primvars_arnold_smoothing))
+        AiNodeSetBool(node, str::smoothing, true);
+
     static const VtIntArray numVerts{ 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
                                       4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
                                       3, 3, 3, 3, 3, 3, 3, 3, 3, 3 };
@@ -947,7 +953,9 @@ AtNode* UsdArnoldReadCone::Read(const UsdPrim &prim, UsdArnoldReaderContext &con
     float frame = time.frame;
     AtNode *node = context.CreateArnoldNode("polymesh", prim.GetPath().GetText());
     ReadMatrix(prim, node, time, context);
-    AiNodeSetBool(node, str::smoothing, true);
+
+    if (!HasAuthoredAttribute(prim, str::t_primvars_arnold_smoothing))
+        AiNodeSetBool(node, str::smoothing, true);
 
     static const VtIntArray numVerts{ 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
                                       4, 4, 4, 4, 4, 4, 4, 4, 4, 4 };
@@ -1005,7 +1013,9 @@ AtNode* UsdArnoldReadCapsule::Read(const UsdPrim &prim, UsdArnoldReaderContext &
     float frame = time.frame;
     AtNode *node = context.CreateArnoldNode("polymesh", prim.GetPath().GetText());
     ReadMatrix(prim, node, time, context);
-    AiNodeSetBool(node, str::smoothing, true);
+
+    if (!HasAuthoredAttribute(prim, str::t_primvars_arnold_smoothing))
+        AiNodeSetBool(node, str::smoothing, true);
 
     // slices are segments around the mesh
     static constexpr int _capsuleSlices = 10;