> higher quality will likely take a few seconds per texture
It takes that long to do a good compression on the format that interpolates 2 colors for each 4x4 block? Huh.
> higher quality will likely take a few seconds per texture
It takes that long to do a good compression on the format that interpolates 2 colors for each 4x4 block? Huh.
It’s not entirely trivial (if you care about texture quality) you’re choosing 2 endpoints in 3d space that can be linearly interpolated to values that best fit 16 points in 3d space.
I may have been a little off with saying seconds per texture but it’s definitely non trivial amounts of time. And ects (mobile) and BC7 are certainly still not something you want to compress to at game load-time.
Some comparisons of texture compression speeds for various formats (from 2020 but on a 12core i9): https://www.aras-p.info/blog/2020/12/08/Texture-Compression-...
It's an open ended optimization problem. You can get bad results very quickly but on high quality settings it can take minutes or hours to compress large textures.
And the newer compression formats have larger block sizes from 8x8 to even 12x12 pixels. ASTC and BC7 are a different beast to the early texture compression formats. You can get pretty awesome image quality at 2 bits per pixel (and slightly less awesome at less than a bit per pixel).
BC1-3 are like that, but BC7 is far, far more complex. The search space is huge.