067f6767d4
The refactor 9c0321ae9b
had the wrong mental model of the backing texture
layout for the atomic workaround.
For 3D textures, the layout is breaking the 3D texture
and reinterpreting the linear location as its 2D
linear location. This breaks the 3D texture Z slices
into non contiguous regions in 2D.
Comments have been added to avoid future confusion.
Pull Request: https://projects.blender.org/blender/blender/pulls/133830