Another OpenGL 4 Feature For Mesa Is Published

Earlier this morning I wrote about Chris Forbes committing texture storage multi-sample support to mainline Mesa and the Intel DRI driver. This OpenGL 4.x extension is now accompanied by a new "RFC" patch-set for providing Mesa support for another GL4 feature.

Chris Forbes' newly-published patches on Sunday morning are for ARB_texture_gather, a feature mandated by OpenGL 4.0 and previously not tackled within the Mesa/Gallium3D world.

As explained by the registry specification, "This extension provides a new set of texture functions (textureGather) to the shading language that determine 2x2 footprint that are used for linear filtering in a texture lookup, and return a vector consisting of the first component from each of the four texels in the footprint."

Forbes explains at the beginning of his new patch-set on the mailing list, "This series implements ARB_texture_gather in core mesa, and the driver side for Gen7 i965. Not quite baked -- green/blue/alpha texture swizzles with VS don't work yet. Everything else works, though (R/0/1 swizzles in VS; all swizzles in FS; textureGather and textureGatherOffset). The first two patches are pretty much what Maxence sent out, but tidied up so they work; the third patch of that original series (st + softpipe) is dropped for now, but shouldn't be hard to reinclude."