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Because transformation happens in the vertex shaders, curvature would not work on low-poly objects. For this reason camera distortion is usually implemented in clip space (only after non-distorted frame is ready)

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Do you mean applying geometric distortion in the fragment shader? I'm not quite sure how that would work (I'm not so familiar with shaders at that level).

I've heard of true 3D bump mapping being done in fragment shaders (not just lighting), but I can't really imagine how more radical geometric distortion could be implemented there.

Fragment shader distortion suffers from another issue: heavy distortions require higher resolutions and (depending on distortion type) higher field of view. Even more radical distortions would require cubemaps of undistorted frames to handle fragmens from behind the camera.

This answer suggests some other ideas on implementing lens distortion: https://stackoverflow.com/a/44492971

Thanks! The cube mapping idea is really interesting — I didn’t know about that approach. However, I doubt it would help in my case, where the distortion is strong enough to flip the depth order of objects.

Maybe these methods could be combined somehow, but it seems simpler to use subdivision (as also mentioned in that thread) — perhaps selectively, for objects near the periphery where distortion is strongest.

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