Instanced static meshes not masking, causing massive overdraw
I have a lot of foliage in my levels they use masked materials to avoid overdraw to a large degree. When placed as a static mesh actor they mask correctly and there is little overdraw as seen in the bush in the first image.
When included in the Instanced Static Mesh Actor they seem to blend over the whole material, ignoring the masking and causing massive overdraw as seen in the second image.
The sea of white that shows massive amounts of overdraw should largely show blue like the bush in the first image where the masking prevents blending from occurring where the alpha of the material is greater that the mask threshold.
I am using 4.14 with the forward renderer and have instanced stereo rendering enabled. I have not tested whether this remains true on the deferred renderer or with instanced stereo rendering disabled.
asked Nov 17 '16 at 08:00 PM in Bug Reports
I submitted a fix just now which will be in 4.15. The change in behavior since 4.13 is just with the view mode when using the forward renderer and doesn't affect actual rendering.
In general there is a limitation with the shader complexity view modes not being very accurate for masked materials. I've written something about this before so I'll just cut/paste it here:
(note this is the bit that is broken in 4.14)
If you're using source code and you're interested to apply the visualization fix yourself, the change is very simple. Just find this code in DeferedShadingRenderer.cpp in the FDeferredShadingSceneRenderer constructor:
and move it to the very end of the function, below if (ShouldForceFullDepthPass(FeatureLevel))
answered Nov 25 '16 at 10:20 AM
Thank you for submitting a bug report. I have reproduced this issue and logged a report for it here: https://issues.unrealengine.com/issue/UE-39002
You can track the report's status as the issue is reviewed by our development staff. Please be aware that this issue may not be prioritized or fixed soon.
answered Nov 23 '16 at 05:00 PM
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