Native bindings to the AMD_seamless_cubemap_per_texture extension.

In unextended OpenGL, cube maps are treated as sets of six, independent texture images. Once a face is selected from the set, it is treated exactly as any other two-dimensional texture would be. When sampling linearly from the texture, all of the individual texels that would be used to to create the final, bilinear sample values are taken from the same cube face. The normal, two-dimensional texture coordinate wrapping modes are honored. This sometimes causes seams to appear in cube maps.

ARB_seamless_cube_map addresses this issue by providing a mechanism whereby an implementation could take each of the taps of a bilinear sample from a different face, spanning face boundaries and providing seamless filtering from cube map textures. However, in ARB_seamless_cube_map, this feature was exposed as a global state, affecting all bound cube map textures. It was not possible to mix seamless and per-face cube map sampling modes during multisampling. Furthermore, if an application included cube maps that were meant to be sampled seamlessly and non-seamlessly, it would have to track this state and enable or disable seamless cube map sampling as needed.

This extension addresses this issue and provides an orthogonal method for allowing an implementation to provide a per-texture setting for enabling seamless sampling from cube maps.

Requires ARB_texture_cube_map.