There are two considerations here. One is whether you get the optimal assembly for min and max operations. Using the GLSL intrinsic is probably the best way to

There are two considerations here. One is whether you get the optimal assembly for min and max operations. Using the GLSL intrinsic is probably the best way to get confidence in that, but it's also likely that compilers are smart enough to figure it out when given other input. If it did compile to an actual branch, it would be much slower. Also note on AVX there are VMINPS and VMAXPS instructions. The other consideration is the style of writing the code. If you were writing for a sequential processor with fast branching, it would be very tempting to write "if in the corner, compute this. If exterior on the edge, compute that. etc." This might save quite a bit in the number of "actual work" operations, but is much more likely to compile into branches, which on a GPU (or SIMD or, likely, any modern CPU) the will cost more than the work saved. So it's very idiomatic when writing shader code to use min and max to combine a bunch of cases into a unified code path that can be executed as a straight line.