Texture artifacts with KTX2 with BasisU supercompression

[callumlinden]

My work flow involves taking a GLB mesh with no textures from a content team, applying X sets of N meshes to it and saving the result off as a X new GLBs.

Then I use gltfpack to optimize/compress the result. The size differences are dramatic but even with -tc -tq 10 I observe artifacts in the textures for the output GLB file. They're not present if texture compression is disabled entirely.

Without -tc:

With -tc -tq 10:

Anything else I can try or is that just the nature of KTX2/BasisU supercompression?

gltfpack 0.21

[zeux]

Some amount of color artifacts is inevitable; I'm surprised it's this drastic but maybe that makes sense on some blocks like this. Could be a bug in the underlying library used (https://github.com/BinomialLLC/basis_universal) but likely just a limitation of format.

KTX2/BasisU has two algorithms, ETC1 & UASTC; I would try UASTC with a low quality setting (eg -tu -tq 3). It's likely to be much larger than ETC1S (which -tc uses), but much much much higher quality. Unfortunately there's not a great middle ground between the two atm (eg "better quality at a fairly small download size").

[callumlinden]

Understood - thank you for the detailed reply.