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Sanitize tangents when creating mesh surfaces to avoid triggering the compressed mesh path in the shader #83179

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merged 1 commit into from
Oct 13, 2023

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clayjohn
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Fixes: #83175

This was a fun one to track down.

In the shader we check if (tangent.x > 0 || tangent.y < 1.0), to see if we should run the uncompressed path. I wrongly assumed that we would never send (0, 1) to the shader because (0, 1) maps to a tangent of (0, 0, -1, 1), but a tangent of (0, 0, -1, 1) maps to (1, 1). However, (-1e8, 0, -1, 1) maps to (0, 1) and sometimes we create tangents that are (-1e8, 0, -1, 1). We can't represent (-1e8, 0, -1, 1) in octahedral tangents anyway, so its fine to just force all cases of (0, 1) to (1, 1)

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@akien-mga akien-mga left a comment

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That looks pretty hacky, but I trust that it's the correct solution :)

@akien-mga akien-mga merged commit 135fa1e into godotengine:master Oct 13, 2023
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@akien-mga
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Thanks!

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TorusMesh exhibits a visible line due to incorrect mesh normals
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