Pixel-Composer/shaders/sh_perlin_smear/sh_perlin_smear.fsh
2023-07-21 12:40:20 +02:00

65 lines
1.3 KiB
GLSL

//
// Simple passthrough fragment shader
//
varying vec2 v_vTexcoord;
varying vec4 v_vColour;
uniform vec2 u_resolution;
uniform vec2 position;
uniform vec2 scale;
uniform int iteration;
uniform float bright;
float random (in vec2 st) { return fract(sin(dot(st.xy, vec2(12.9898, 78.233))) * 43758.5453123); }
float noise (in vec2 st) {
vec2 i = floor(st);
vec2 f = fract(st);
float _my = abs(i.y - (floor(i.y / 2.) * 2.));
float a, b, c;
if(_my < 1.) {
if(f.x > f.y) {
a = random(i);
b = random(i + vec2(1.0, 0.0));
c = random(i + vec2(1.0, 1.0));
} else {
a = random(i);
b = random(i + vec2(0.0, 1.0));
c = random(i + vec2(1.0, 1.0));
}
} else {
if(1. - f.x < f.y) {
a = random(i);
b = random(i + vec2(1.0, 0.0));
c = random(i + vec2(1.0, 1.0));
} else {
a = random(i);
b = random(i + vec2(0.0, 1.0));
c = random(i + vec2(1.0, 1.0));
}
}
vec2 u = f * f * (3.0 - 2.0 * f);
return mix(mix(a, b, u.x), c, u.y);
}
void main() {
vec2 st = v_vTexcoord + position;
vec2 pos = st * scale;
float amp = bright;
float n = 0.;
for(int i = 0; i < iteration; i++) {
n += noise(pos) * amp;
amp *= .5;
pos *= 2.;
}
gl_FragColor = vec4(vec3(n), 1.0);
}