Megalights support for anisoptropic materials

Development Rendering
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Hello folks,

We have noticed that, with MegaLights enabled, our anisotropic materials were rendering without any anisotropy.

After investigating, I noticed SUPPORTS_ANISOTROPIC_MATERIALS was not passed to FShadeLightSamplesCS::ModifyCompilationEnvironment. Adding it fixes the issue.

Was this intentional? Is there any side effects we should know about?

Note that we are not using Substrate, but Substrate seems to have the same issue.

Thanks

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Steps to Reproduce

  • Enable MegaLights.
  • Create a sphere and apply a material that uses anisotropy
  • Add point light to the scene
  • Notice the lack of anisotropy
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Hi Olivier,

Thanks for reaching out. Can you please send me a project with the setup you describe? That way, I can quickly check the differences and potentially submit a change to get anisotropy working for Megalights again.

Cheers,

Tim

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Hi Olivier,

Thanks for the quick turnaround. I verified that material anisotropy is either broken or disabled for a specific reason, so I filed a Jira with the dev team to get some clarification. I also proposed your fix to them, so I am looking for feedback from them on it. You can follow along via the public issues link here: https://issues.unrealengine.com/issue/UE\-373716\. Please let me know if you have any further questions.

Cheers,

Tim

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That could work as a temporary workaround. I will close out this case then, but keep an eye on the public issue tracker for any updates. If you haven’t seen any traction in a reasonable timeframe, feel free to create a case and ping me on it.

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Here you go. Hopefully everything is in there. Note that I’ve used a point light here, but it applies to all light types, including directional if you enable the directional support Cvar (r.MegaLights.DirectionalLights 1).

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Upload somehow didn’t work.

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Great thanks! In the mean time I changed my fix a little to support toggling on/off anisotropy support at runtime (r.AnisotropicMaterials 0) by implementing a shader permutation, similar to what is done for the FClusteredShadingPS shader.

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