Pseudorandom Generator

[Josh]

Not tested much, just an experiment. Can be slightly faster (25%) than rand() or mt19937:

float random(const float x, const float y)
{
    const float m = sin(x * 12.9898f + y * 78.233f) * 43758.5453f;
    return m - floor(m);
}

 

[Genebris]

I don't get it, it returns the same value for the same input?

[Josh]

Yeah, that's the seed. It's from GLSL, something I was just messing around with, and I wanted to save the code somewhere.

[havenphillip]

That's cool. It didn't like "float m" as a constant for some reason idk.

 

[klepto2]

Just a side node: On intel integrated gfx card this glsl code is producing horrible noise. But you can overcome this issue by significantly lowering the 

 43758.5453f

On 6/4/2022 at 12:44 PM, havenphillip said:

That's cool. It didn't like "float m" as a constant for some reason idk.

I think Josh's code is a conversion to c++ code.  Yours is correct for glsl. 

 

Edited:

As a side node, this should always replaced with a noise texture lookup in glsl when possible. While it is faster in c++ than traditional random generators it will slow down glsl shaders when it is used to much. A simple texture lookup is much faster. (one way is to pregenerate a texture with this function and later use this texture to lookup the random number.