While writing a shader program today, I encountered a situation where I have to use % to find the remainder. GLSL gave me an error saying that it is not available in the current version.
I've tried several problems. GLSL doesn't support recursive function and while loops, which is needed if I want to create a function that can give me the result of (a % b).
So, I'm currently stuck. Can someone help me with this?
Edit. I was trying to emulate a CRT screen using some shader code from this website as reference code. I wanted to modify the color of the pixels at certain row and columns, so I needed to make use of the modulo operator.
At first, I thought that the modulus function was done using the % operator. It didn't work, so I tried using recursive function/while loop as a workaround
for modulus function, which didn't work either.
GLSL doesn't support recursive function and while loops, which is needed if I want to create a function that can give me the result of (a % b).
First, neither recursion nor looping is necessary to compute a mod b. That's easily done by a - (b * floor(a/b)).
Which is exactly what the built-in mod function does. If your version of GLSL doesn't support the % operator, then you're probably not able to get real integers either. So just use the mod function on your values.
来源：https://stackoverflow.com/questions/35155598/unable-to-use-in-glsl