Optimize GPU memory usage in Editor when viewport is inactive

Source/Engine/Graphics/RenderTask.cpp

@@ -46,9 +46,9 @@ void RenderTask::DrawAll()
     for (auto task : Tasks)
     {
         if (task->CanDraw())
-        {
             task->OnDraw();
-        }
+        else
+            task->OnIdle();
     }
 }
 
@@ -84,6 +84,10 @@ void RenderTask::OnDraw()
     OnEnd(context);
 }
 
+void RenderTask::OnIdle()
+{
+}
+
 void RenderTask::OnBegin(GPUContext* context)
 {
     Begin(this, context);
@@ -325,6 +329,9 @@ void SceneRenderTask::OnPostRender(GPUContext* context, RenderContext& renderCon
     OnCollectDrawCalls(renderContextBatch, SceneRendering::PostRender);
 
     PostRender(context, renderContext);
+
+    if (Buffers)
+        Buffers->ReleaseUnusedMemory();
 }
 
 Viewport SceneRenderTask::GetViewport() const
@@ -424,6 +431,14 @@ bool SceneRenderTask::CanDraw() const
     return RenderTask::CanDraw();
 }
 
+void SceneRenderTask::OnIdle()
+{
+    RenderTask::OnIdle();
+
+    if (Buffers)
+        Buffers->ReleaseUnusedMemory();
+}
+
 MainRenderTask::MainRenderTask(const SpawnParams& params)
     : SceneRenderTask(params)
 {