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Shader Complexity view mode different between deferred and forward renderer

I tried to figure out why the shader complexity of my test scene was mostly red until I changed back to the default renderer.

The two images show the same scene without any changes to the materials. Is this a bug or do basic materials have a higher instruction count with forward shading enabled?

Deffered: alt text

Forward: alt text

Product Version: UE 4.14 Preview
deferred.png (200.6 kB)
forward.png (292.7 kB)
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asked Nov 06 '16 at 06:34 PM in Bug Reports

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avatar image D'Arcadius Nov 07 '16 at 10:46 AM

I have the same issue. I would like to know an answer to this as well.

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2 answers: sort voted first

Hi Congaz2,

This is expected behavior. You can read Daniel's response here on the forums: https://forums.unrealengine.com/showthread.php?126489-Test-the-Forward-Renderer-in-your-PC-VR-projects-with-the-4-14-Preview&p=618082&viewfull=1#post618082

Shader complexity is expected to increase because more of the lighting operations are done in the base pass shader. Lights didn't contribute to shader complexity in the deferred renderer, now those are in the base pass shader.


Shader complexity is useful for comparing between materials within forward, but not useful for comparing deferred vs forward. Use ProfileGPU for that.

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answered Nov 08 '16 at 08:09 PM

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Tim Hobson ♦♦ STAFF
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I haven't looked at how shader complexity view shader is working, but I would assume that it is either not fully functional for forward mode, or it is accumulating complexity for multiple lights. You can rule out the latter one by changing lighting setup in the scene.

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answered Nov 07 '16 at 01:57 PM

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avatar image Congaz2 Nov 08 '16 at 08:43 AM

There is only one directional light in the scene. I tried it with three and saw no difference. I guess its just not optimized for forward shading. I Hope we get a fix for that with the final 4.14

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