Multiple fixes for compressed meshes #88738
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clayjohn
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bug
topic:rendering
topic:import
regression
cherrypick:4.2
…are good enough when using compression
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akien-mga
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Feb 27, 2024
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I'm not really qualified to do a technical review here, but given the bugs it fixes and Clay's expertise on this area, I'm going to merge so we can get the fixes tested in the next dev snapshot.
Post merge code reviews from rendering/import contributors still welcome :)
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Thanks! |
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Cherry-picked for 4.2.2. |
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Fixes: #85406 (fixed by disabling compression when mesh has bogus tangents)
Fixes: #84270 (fixed by disabling compression when we generate bogus tangents because the mesh has bogus UVs)
Fixes: #83345
Fixes: #88619 (fixed by avoiding singularity when generating tangents and normal is exactly (0,1,0)
There are two different fixes here:
When generating dummy tangents from normals, there is a singularity when the normal is exactly (0, 1, 0). In that case we generate bad tangents. So we avoid that by using the normal vector and scrambling the channels to generate the tangent vector. This works in all cases except for when normal is (0,0,0).
When users import bogus meshes the normal/tangent compression fails. It requires that both normals and tangents are valid and are actually perpendicular to each other. Since it is difficult to discover the "force disable compression option", we just detect these cases and silently force disable compression for the user.