So: if we need the q coord in the end (solely determined by the texture
target, i.e. 2d / 1d / texrect targets) we swap the third and 4th row.
Additionally, if we don't have texgen but 4 tex coords submitted, we swap
- column 3 and 4 (for the 2d / 1d / texrect targets) since the the q coord
+ column 3 and 4 (for the 2d / 1d / texrect targets) since the q coord
will get submitted in the "wrong", i.e. 3rd, slot.
If an app submits 3 coords for 2d targets, we assume it is saving on vertex
size and using the texture matrix to swap the r and q coords around (ut2k3