As a C/C++ and graphics programmer, I love NaN. It allows saving space by not having to carry an extra is_valid boolean for uninitialized values or regions of data that are masked.
For textures, they are great as they don't interpolate w/ nearby neighbors and properly discard fragments & vertices without the aforementioned cost of an extra boolean attribute.
For textures, they are great as they don't interpolate w/ nearby neighbors and properly discard fragments & vertices without the aforementioned cost of an extra boolean attribute.