How to deal with NaN or inf in OpenGL ES 2.0 shaders

Question

This is based on the question: Best way to detect NaN's in OpenGL shaders

Standard GLSL defines isnan() and isinf() functions for detection. OpenGL ES 2.0 shading language doesn't. How can I deal with NaNs and Infs nevertheless?

Answer 1

You can check for NaN via a condition that will only be true for NaN:

bool isNan(float val)
{
  return (val <= 0.0 || 0.0 <= val) ? false : true;
}

isinf is a bit more difficult. There is no mechanism to convert the float into its integer representation and play with the bits. So you'll have to compare it against a suitably large number.