source/blender/render/hydra/final_engine.cc

@@ -109,7 +109,7 @@ void FinalEngine::prepare_for_render(Depsgraph *depsgraph)
   if (light_tasks_delegate_) {
     light_tasks_delegate_->set_camera_and_viewport(
         free_camera_delegate_->GetCameraId(), pxr::GfVec4d(0, 0, resolution_[0], resolution_[1]));
-    tasks_ = light_tasks_delegate_->get_tasks();
+    tasks_ = light_tasks_delegate_->get_tasks(scene->r.alphamode == R_ALPHAPREMUL);
   }
   tasks_.push_back(render_task_delegate_->get_task());
 
@@ -147,7 +147,7 @@ void FinalEngineGPU::render(Depsgraph *depsgraph)
 
   GPU_framebuffer_bind(framebuffer);
 
-  float clear_color[4] = {0.0f, 0.0f, 0.0f, 1.0f};
+  float clear_color[4] = {0.0f, 0.0f, 0.0f, 0.0f};
 
   GPU_framebuffer_clear_color_depth(framebuffer, clear_color, 1.0f);
 

source/blender/render/hydra/light_tasks_delegate.cc

@@ -18,12 +18,17 @@ LightTasksDelegate::LightTasksDelegate(pxr::HdRenderIndex *parent_index,
   GetRenderIndex().InsertTask<pxr::HdxSimpleLightTask>(this, simple_task_id_);
 }
 
-pxr::HdTaskSharedPtrVector LightTasksDelegate::get_tasks()
+pxr::HdTaskSharedPtrVector LightTasksDelegate::get_tasks(const bool isTransparent)
 {
   /*Note that this task is intended to be the first "Render Task",
   so that the AOV's are properly cleared, however it
   does not spawn a HdRenderPass.*/
-  return {GetRenderIndex().GetTask(skydome_task_id_), GetRenderIndex().GetTask(simple_task_id_)};
+  pxr::HdTaskSharedPtrVector tasks;
+  if (!isTransparent) {
+    tasks.push_back(GetRenderIndex().GetTask(skydome_task_id_));
+  }
+  tasks.push_back(GetRenderIndex().GetTask(simple_task_id_));
+  return tasks;
 }
 
 void LightTasksDelegate::set_camera_and_viewport(pxr::SdfPath const &camera_id,

source/blender/render/hydra/light_tasks_delegate.h

@@ -14,7 +14,7 @@ class LightTasksDelegate : public pxr::HdSceneDelegate {
   LightTasksDelegate(pxr::HdRenderIndex *parentIndex, pxr::SdfPath const &delegate_id);
   ~LightTasksDelegate() override = default;
 
-  pxr::HdTaskSharedPtrVector get_tasks();
+  pxr::HdTaskSharedPtrVector get_tasks(const bool isTransparent);
   void set_camera_and_viewport(pxr::SdfPath const &camera_id, pxr::GfVec4d const &viewport);
 
   /* Delegate methods */

source/blender/render/hydra/viewport_engine.cc

@@ -222,9 +222,10 @@ void ViewportEngine::render(Depsgraph * /* depsgraph */)
   /* Empty function */
 }
 
-void ViewportEngine::render(Depsgraph * /* depsgraph */, bContext *context)
+void ViewportEngine::render(Depsgraph *depsgraph, bContext *context)
 {
   ViewSettings view_settings(context);
+  const Scene *scene = DEG_get_evaluated_scene(depsgraph);
   if (view_settings.width() * view_settings.height() == 0) {
     return;
   };
@@ -254,7 +255,7 @@ void ViewportEngine::render(Depsgraph * /* depsgraph */, bContext *context)
 
   pxr::HdTaskSharedPtrVector tasks;
   if (light_tasks_delegate_) {
-    tasks = light_tasks_delegate_->get_tasks();
+    tasks = light_tasks_delegate_->get_tasks(scene->r.alphamode == R_ALPHAPREMUL);
   }
   tasks.push_back(render_task_delegate_->get_task());