Here's a first attempt at a patch series to implement BPTC texture compression in the i965 driver on Gen>=7.
Getting it to work on the hardware is pretty trivial as it's just a case of adding some new Mesa format enums and then plugging them together with the right Intel surface type. However GL requires that you are able to get the library to compress textures on the fly so we need a compressor too. I think for BPTC it doesn't really make much sense to actually use this because it takes a very long time to search the entire space and compress an image properly. For example the NVidia compressor takes in the order of an hour for a full-screen image. Instead I've just done the minimal work needed to get something that gives vaguely passable results. For the two normalized formats I've just made it first compress each block with the existing DXT3 compressor and then convert the block to mode 4 of BPTC. This ends up being worse than just using DXT3 directly because it will lose a bit from the green component of the endpoints and each alpha index will be 3 bits instead of 4, but it looks ok. For the two half-float formats I've written a custom compressor which just has a very simple algorithm and always uses mode 3. I've also written software texel fetch functions for all of the formats. I guess in theory we don't need these because we should just be able to use the hardware to decompress if someone calls glGetTexImage. However Mesa has a static assert to require a texel fetch function and it seemed like a good way to learn more about the format so I wrote the functions anyway. It also means we can enable the extension on the software rasterizer. I've written a Piglit test for the decompressor with the normalized formats. I also tested the half-float decompressor using NVidia's sample texture which tries every mode. It would be good to make a Piglit test that does this as well. - Neil _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
