Translucency with DepthWrite

Development Rendering
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9

I Stephane,

That is a good suggestion, however we actually have two opaque and two translucent passes and we want it to work on a per object basis and the custom depth buffer is shared between object from what I can tell, so it gets more complex.

Here is what I ended up doing in case it is useful for someone else. I added a material TranslucencyWritesDepth bool parameter with an override on the material instance as well. Then in BasePassRendering.cpp, I modified the

FMeshPassProcessor* CreateTranslucencyAllPassProcessor(…)

To use:

PassDrawRenderState.SetDepthStencilAccess(FExclusiveDepthStencil::DepthWrite_StencilWrite); PassDrawRenderState.SetDepthStencilState(TStaticDepthStencilState<true, CF_DepthNearOrEqual>::GetRHI());Then in

TranslucencyRendering.cpp

in

RenderTranslucencyViewInner()

I added

if (TranslucencyPass == ETranslucencyPass::TPT_AllTranslucency )
{
	PassParameters->RenderTargets.DepthStencil = FDepthStencilBinding(SceneDepthTexture, ERenderTargetLoadAction::ELoad, ERenderTargetLoadAction::ELoad, FExclusiveDepthStencil::DepthWrite_StencilWrite);
}

Then in

MeshPassProcessor.inl

in

template<typename PassShadersType, typename ShaderElementDataType>void FMeshPassProcessor::BuildMeshDrawCommands(

I added

PipelineState.BlendState = DrawRenderState.GetBlendState();
if (MeshPassType == EMeshPass::TranslucencyAll || MeshPassType == EMeshPass::TranslucencyEnvironment)
{
    if (MaterialResource.IsTranslucencyWritingDepth() && DrawRenderState.GetDepthStencilAccess() == FExclusiveDepthStencil::DepthWrite_StencilWrite)
    {
       PipelineState.DepthStencilState = TStaticDepthStencilState<true, CF_DepthNearOrEqual>::GetRHI();
    }
    else
    {
       PipelineState.DepthStencilState = TStaticDepthStencilState<false, CF_DepthNearOrEqual>::GetRHI();
    }
}
else
{
    PipelineState.DepthStencilState = DrawRenderState.GetDepthStencilState();
}

There were additional modifications but that was the core of it and we can select which translucent meshes we want to behave this way and which continue to behave as before. Thanks for your help.