ffset) tex2D(s, coords, offset)
#define tex2Dlodoffset(s, coords, offset) tex2Dlod(s, coords, offset)
#define tex2Dgather(s, t, c) tex2Dgather##c(s, t)
#define tex2Dgatheroffset(s, t, o, c) tex2Dgather##c(s, t, o)
#define tex2Dgather0 tex2DgatherR
#define tex2Dgather1 tex2DgatherG
#define tex2Dgather2 tex2DgatherB
#define tex2Dgather3 tex2DgatherA