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// todo: this optimization is currently broken
DrawingContext.bSceneColorCopyIsUpToDate = (DrawingContext.TranslucenyPassType == ETranslucencyPass::TPT_SeparateTranslucency);
The optimization doesn't work because the bSceneColorCopyIsUpToDate is always false when it's evaluated in the code above.
As reported on UDN.
Create a test level with multiple meshes with a transparent material which reads from SceneColor, using separate translucency
Put a breakpoint in FTranslucencyDrawingPolicyFactory::DrawMesh and notice that each draw call does a SceneColor copy.
There's no existing public thread on this issue, so head over toAnswerHub just mention UE-35354 in the post.