GLSL sign function

Posted on June 15, 2012 Updated on June 15, 2012

The GLSL sign function always seems a great way to remove some unnecessary if statements from my shaders, but I never seem to get to use it because I always need to consider zero as either positive or negative, and not its own special value.

Anyway, I just realized you can accomplish the same thing with the step function.

step(0, x)*2 - 1;

This will return -1.0 if x < 0, and 1.0 if x >= 0.

Which is not terribly readable, hence this overly verbose function

//returns -1.0 if x < 0, and 1.0 if x >= 0
float signGreaterEqualZero(float x)
{
	return step(0, x)*2 - 1;
}