[Bf-blender-cvs] [182443da4b7] universal-scene-description: USD import: 'preview' purpose material fallback

[Michael Kowalski]

Commit: 182443da4b7f38a71f80e41fa8878a4a78cba64f
Author: Michael Kowalski
Date:   Tue Aug 31 15:49:11 2021 -0400
Branches: universal-scene-description
https://developer.blender.org/rB182443da4b7f38a71f80e41fa8878a4a78cba64f

USD import: 'preview' purpose material fallback

Added logic to explicitly query bound materials
with purpose 'preview', if querying 'allPurpse' bound
materials returns no result.

===================================================================

M	source/blender/io/usd/intern/usd_reader_mesh.cc

===================================================================

diff --git a/source/blender/io/usd/intern/usd_reader_mesh.cc b/source/blender/io/usd/intern/usd_reader_mesh.cc
index cc5a542625b..0d4af292439 100644
--- a/source/blender/io/usd/intern/usd_reader_mesh.cc
+++ b/source/blender/io/usd/intern/usd_reader_mesh.cc
@@ -723,6 +723,11 @@ void USDMeshReader::assign_facesets_to_mpoly(double motionSampleTime,
 
       pxr::UsdShadeMaterial subset_mtl = subset_api.ComputeBoundMaterial();
 
+      if (!subset_mtl) {
+        /* Check for a preview material as fallback. */
+        subset_mtl = subset_api.ComputeBoundMaterial(pxr::UsdShadeTokens->preview);
+      }
+
       if (!subset_mtl) {
         continue;
       }
@@ -753,7 +758,14 @@ void USDMeshReader::assign_facesets_to_mpoly(double motionSampleTime,
   if (r_mat_map->empty()) {
     pxr::UsdShadeMaterialBindingAPI api = pxr::UsdShadeMaterialBindingAPI(prim_);
 
-    if (pxr::UsdShadeMaterial mtl = api.ComputeBoundMaterial()) {
+    pxr::UsdShadeMaterial mtl = api.ComputeBoundMaterial();
+
+    if (!mtl) {
+      /* Check for a preview material as fallback. */
+      mtl = api.ComputeBoundMaterial(pxr::UsdShadeTokens->preview);
+    }
+
+    if (mtl) {
 
       pxr::SdfPath mtl_path = mtl.GetPath();