Substrate on Blendable GBuffers displays Black in editor Unlit view mode.

anonymous-edc · March 11, 2026, 1:57am

When using Substrate materials with the Blendable GBuffer, the Unlit editor view mode just renders black.

Adding this to line 1895 of BasePassPixelShader.usf fixes the issue:

	#if USE_DEVELOPMENT_SHADERS
		TopLayerData.UnlitViewBaseColor = Export.BaseColor;
	#endif

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anonymous-edc · March 11, 2026, 1:58am

Steps to Reproduce

Set project to use Substrate Blendable GBuffer.
Make a material, using a substrate slab BSDF.
Change any viewport to unlit view mode with that material in it.
Notice that the material appears black.
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TimStullich · March 18, 2026, 10:31am

Hi Mark,

Good catch on that! I confirmed that the unlit view mode is broken when using Substrate materials with a blendable GBuffer. I created a Jira ticket to track the integration of your proposed fix: https://issues.unrealengine.com/issue/UE\-370472\. Feel free to let me know if you have any more questions.

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