Backface Shadow Casting


I have some problems with imported Quixel Megascan Meshes. To be exact: With the open ones (meshes that are not closed and have a visible backface or invisible backface as stated withing the quixel bridge details of the mesh)

I tried fixing the issue by enabling two-sided shadows in the material and the mesh properties. But nothing changed. what am I doing wrong?

e.g Try importing the Quixel massive sandstone asset and set a directional light to shine from the open side of the mesh onto a plane. The shadow will be really weird and messy.

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Not entirely sure what your issue is, as you’ve stated you have a problem but haven’t really said what it is.

What you are seeing here as transparency is the backside of a plane that is not rendered because the normals are facing the other direction. I suspect the asset is working as intended because backfaces should not be rendered unless you have two-sided enabled in the material.

However Nanite does not support two-sided materials and so there is no one-click fix for those faces not being rendered (which is intended behaviour).

The problem is the shadows. I need the open mesh to cast a shadow when lit from the open side. Is that possible? But as nanite. They don’t need to get visible just cast shadows.

Yes turning the mesh from Nanite to normal does fix the issue. But is there a workaround for nanite? Or is the only option to turn the mesh into a closed asset?

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As far as I know, nanite currently doesn’t support two-sided shadows. So you could try to block the light with some additional meshes or close the nanite mesh.


Probably too late for @1someT , but I faced the same issue and found the cause:
Although with Nanite enabled U lose your shadows, probably the issue is because U have Raytracing enabled and Ray Traced Shadows Disabled:


Hope it helps