Mesa Enables S3TC Support For 3D Textures

The feature work continues pouring in for Mesa 24.0 with new OpenGL and Vulkan driver features continuing to be enabled.

The latest addition hitting Mesa 24.0-devel worth mentioning is allowing S3 Texture Compression (S3TC) for 3D textures.

Contributor Pavel Asyutchenko summed up in the merge request:

"This is allowed by D3D, RADV, ANV and Nvidia GL drivers at least, so it should work on any hardware with S3TC.

OpenXRay uses DXT5-compressed 3D texture for rain splash effects. I've confirmed this patch makes it work properly on radeonsi and zink->nvidia."

There was initially some debate whether S3TC for 3D textures is supposed to be allowed for desktop OpenGL or just OpenGL ES 3.x. It was agreed as a likely specification issue that is now being raised with Khronos so for now at least this support is just enables for GLES3 contexts.

For those wondering about OpenXRay as one of the software that benefits from it, OpenXRay is an open-source improved version of the X-Ray Engine used by the STALKER game series. OpenXRay is striving to be a drop-in replacement for that original engine.