source/blender/render/hydra/sceneDelegate/blenderSceneDelegate.cc

@@ -105,6 +105,14 @@ VtIntArray BlenderSceneDelegate::GetInstanceIndices(SdfPath const &instancerId,
   return ret;
 }
 
+GfMatrix4d BlenderSceneDelegate::GetInstancerTransform(SdfPath const &instancerId)
+{
+  LOG(INFO) << "GetInstancerTransform: " << instancerId.GetString();
+  // TODO: add a separate object for instancer for cleaner handling code
+  // Actual instancer transform is get here
+  return GfMatrix4d(1.0);
+}
+
 size_t BlenderSceneDelegate::SampleInstancerTransform(SdfPath const &instancerId, size_t maxSampleCount,
                                                       float *sampleTimes,  GfMatrix4d *sampleValues)
 {
@@ -115,6 +123,19 @@ size_t BlenderSceneDelegate::SampleInstancerTransform(SdfPath const &instancerId
   return ret;
 }
 
+size_t BlenderSceneDelegate::SamplePrimvar(SdfPath const &id, TfToken const &key, size_t maxSampleCount,
+                                           float *sampleTimes, VtValue *sampleValues)
+{
+  // TODO: add a separate object for instancer for cleaner handling code
+  if (id.GetName() == "Instancer") {
+    MeshData *m_data = mesh_data(id.GetParentPath());
+    if (m_data) {
+      return m_data->sample_instancer_primvar(key, maxSampleCount, sampleTimes, sampleValues);
+    }
+  }
+  return HdSceneDelegate::SamplePrimvar(id, key, maxSampleCount, sampleTimes, sampleValues);
+}
+
 void BlenderSceneDelegate::update_collection(bool remove, bool visibility)
 {
   if (visibility) {
@@ -370,6 +391,10 @@ VtValue BlenderSceneDelegate::Get(SdfPath const& id, TfToken const& key)
 {
   LOG(INFO) << "Get: " << id.GetString() << " " << key.GetString();
   ObjectData *obj_data = object_data(id);
+  // TODO: add a separate object for instancer for cleaner handling code
+  if (!obj_data && id.GetName() == "Instancer") {
+    obj_data = object_data(id.GetParentPath());
+  }
   if (obj_data) {
     return obj_data->get_data(key);
   }
@@ -387,6 +412,12 @@ HdPrimvarDescriptorVector BlenderSceneDelegate::GetPrimvarDescriptors(SdfPath co
   if (mesh_data(id)) {
     return mesh_data(id)->primvar_descriptors(interpolation);
   }
+  // TODO: add a separate object for instancer for cleaner handling code
+  else if (id.GetName() == "Instancer") {
+    if (MeshData *data = mesh_data(id.GetParentPath())) {
+      return data->instancer_primvar_descriptors(interpolation);
+    }
+  }
   HdPrimvarDescriptorVector primvars;
   return primvars;
 }
@@ -412,6 +443,12 @@ GfMatrix4d BlenderSceneDelegate::GetTransform(SdfPath const& id)
   if (obj_data) {
     return obj_data->transform();
   }
+  // TODO: add a separate object for instancer for cleaner handling code
+  else if (id.GetName() == "Instancer") {
+    if (MeshData *mesh = mesh_data(id.GetParentPath())) {
+      return mesh->transform().GetInverse();
+    }
+  }
   if (id == WorldData::prim_id(this)) {
     return world_data->transform();
   }

source/blender/render/hydra/sceneDelegate/blenderSceneDelegate.h

@@ -34,8 +34,11 @@ public:
   pxr::SdfPath GetInstancerId(pxr::SdfPath const &primId) override;
   pxr::SdfPathVector GetInstancerPrototypes(pxr::SdfPath const &instancerId) override;
   pxr::VtIntArray GetInstanceIndices(pxr::SdfPath const &instancerId, pxr::SdfPath const &prototypeId) override;
+  pxr::GfMatrix4d GetInstancerTransform(pxr::SdfPath const &instancerId);
   size_t SampleInstancerTransform(pxr::SdfPath const &instancerId, size_t maxSampleCount,
                                   float *sampleTimes, pxr::GfMatrix4d *sampleValues) override;
+  size_t SamplePrimvar(pxr::SdfPath const &id, pxr::TfToken const &key, size_t maxSampleCount,
+                       float *sampleTimes, pxr::VtValue *sampleValues) override;
 
  private:
   ObjectData *object_data(pxr::SdfPath const &id);

source/blender/render/hydra/sceneDelegate/mesh.cc

@@ -44,6 +44,9 @@ VtValue MeshData::get_data(TfToken const &key)
   else if (key == HdPrimvarRoleTokens->textureCoordinate) {
     ret = uvs;
   }
+  else if (key == HdInstancerTokens->instanceTransform) {
+    ret = instances;
+  }
   return ret;
 }
 
@@ -82,6 +85,16 @@ HdPrimvarDescriptorVector MeshData::primvar_descriptors(HdInterpolation interpol
   return primvars;
 }
 
+HdPrimvarDescriptorVector MeshData::instancer_primvar_descriptors(HdInterpolation interpolation)
+{
+  HdPrimvarDescriptorVector primvars;
+  if (interpolation == HdInterpolationInstance) {
+    primvars.emplace_back(HdInstancerTokens->instanceTransform, interpolation,
+                          HdPrimvarRoleTokens->none);
+  }
+  return primvars;
+}
+
 VtIntArray MeshData::instance_indices()
 {
   VtIntArray ret(instances.size());
@@ -93,12 +106,21 @@ VtIntArray MeshData::instance_indices()
 
 size_t MeshData::sample_instancer_transform(size_t maxSampleCount, float *sampleTimes, GfMatrix4d *sampleValues)
 {
-  size_t n = std::min(instances.size(), maxSampleCount);
-  for (size_t i = 0; i < n; ++i) {
-    sampleTimes[i] = 0.0f;
-    sampleValues[i] = gf_matrix_from_transform(instances[i]->mat);
+  *sampleTimes = 0.0f;
+  *sampleValues = GfMatrix4d(1.0);
+  return 1;
+}
+
+size_t MeshData::sample_instancer_primvar(TfToken const &key, size_t maxSampleCount, float *sampleTimes, VtValue *sampleValues)
+{
+  if (key == HdInstancerTokens->instanceTransform) {
+    if (maxSampleCount > 0) {
+      sampleTimes[0] = 0.0f;
+      sampleValues[0] = instances;
+      return 1;
     }
-  return n;
+  }
+  return 0;
 }
 
 void MeshData::add_instance(DupliObject *dupli)
@@ -108,7 +130,11 @@ void MeshData::add_instance(DupliObject *dupli)
     scene_delegate->GetRenderIndex().InsertInstancer(scene_delegate, instancer_id);
     LOG(INFO) << "Add instancer: " << name() << " id=" << instancer_id.GetAsString();
   }
-  instances.push_back(dupli);
+  if (instances.empty()) {
+    // USD hides the prototype mesh when instancing in contrary to the Blender, so we must add it back implicitly
+    instances.push_back(GfMatrix4d(1.0));
+  }
+  instances.push_back(transform().GetInverse() * gf_matrix_from_transform(dupli->mat));
   LOG(INFO) << "Add instance: " << instancer_id.GetAsString() << " " << dupli->random_id;
 }
 

source/blender/render/hydra/sceneDelegate/mesh.h

@@ -25,8 +25,10 @@ public:
   Material *material();
   pxr::HdMeshTopology mesh_topology();
   pxr::HdPrimvarDescriptorVector primvar_descriptors(pxr::HdInterpolation interpolation);
+  pxr::HdPrimvarDescriptorVector instancer_primvar_descriptors(pxr::HdInterpolation interpolation);
   pxr::VtIntArray instance_indices();
   size_t sample_instancer_transform(size_t maxSampleCount, float *sampleTimes, pxr::GfMatrix4d *sampleValues);
+  size_t sample_instancer_primvar(pxr::TfToken const &key, size_t maxSampleCount, float *sampleTimes, pxr::VtValue *sampleValues);
 
   void add_instance(DupliObject *dupli);
 
@@ -42,7 +44,7 @@ public:
   pxr::VtVec3fArray normals;
   pxr::VtVec2fArray uvs;
 
-  std::vector<DupliObject *> instances;
+  pxr::VtMatrix4dArray instances;
 };