Unity Continues Crunching More Out Of Crunch Texture Compression

Unity is one of the big public users of the open-source Crunch DXT texture compression library. While it's no longer maintained by Rich Geldreich / Binomial, Unity has continued advancing this open-source code to further improve the compression ratio and speed.

For months Unity has been talking about their promising findings with Crunch. But this is the project that Rich Geldreich, the former Valve developer, previously expressed regret having open-sourced all of it. While he is on to working on better and more advanced technologies at his Binomial startup, Unity is working to squeeze more out of this open-source library.

They have managed few percent gains to the compressed size and compression time via a few different avenues. Replacing the chunk encoding scheme, encoding selector indicies without prediction, removing duplicate endpoints and selectors, using XOR deltas, and improving the Zeng reorddering algorithm has yielded measurable performance improvements.

Unity has been extending Crunch as well to not only support DXT textures but also ETC/ETC2 textures. They also see potential in supporting other formats in the future as well.

Those interested in some heavy technical reading this weekend about GPU texture compression and its effects can find all the details via the Unity blog.