Does GLSL have any pre-defined constants for +/-infinity or NaN? I'm doing this as a workaround but I wonder if there is a cleaner way:
// GLSL FRAGMENT SHADER #version 410 <snip> const float infinity = 1. / 0.; void main () { <snip> } I am aware of the isinf function but I need to assign infinity to a variable so that does not help me.
Like Nicol mentioned, there are no pre-defined constants.
However, from OpenGL 4.1 on, your solution is at least guaranteed to work and correctly generate an infinite value.
See for example in glsl 4.4:
4.7.1 Range and Precision
...
However, dividing a non-zero by 0 results in the appropriately signed IEEE Inf: If both positive and negative zeros are implemented, the correctly signed Inf will be generated, otherwise positive Inf is generated.
Be careful when you use an older version of OpenGL though:
For example in glsl 4.0 it says:
4.1.4 Floats
...
Similarly, treatment of conditions such as divide by 0 may lead to an unspecified result, but in no case should such a condition lead to the interruption or termination of processing.
There are no pre-defined constants for it, but there is the isinf function to test if something is infinity.
While I'm at it, are there constants for other things like FLT_MAX FLT_EPSILON etc the way there are in C?
No, there are not.