🅱ractal 🅱ois 👌

fractalnoise.glsl

float rand(vec2 p)
{
    return fract(sin(dot(p, vec2(34.8313, 90.1394))) * 9813.91);
}

float noise(vec2 p)
{
    vec2 f = fract(p);
    vec2 i = floor(p);
    
    float noise[4];
    noise[0] = rand(i);
    noise[1] = rand(i + vec2(1,0));
    noise[2] = rand(i + vec2(0,1));
    noise[3] = rand(i + vec2(1,1));
    
    return mix(mix(noise[0], noise[1], f.x),
               mix(noise[2], noise[3], f.x),
               smoothstep(0.0, 1.0, f.y));
}

float fbm(vec2 p, int octave)
{
    float amp = 0.5;
    float ret = 0.0;
    
    while(octave != 0)
    {
        ret += amp * noise(p);
        amp *= 0.5;
        //p *= float(octave) / 2.0;
        p *= 2.0;
        octave--;
    }
    
    return ret;
}