Pixel-Composer/build/Windows/0/cache/sh_perlin.shader

//
// Simple passthrough vertex shader
//
attribute vec3 in_Position;                  // (x,y,z)
//attribute vec3 in_Normal;                  // (x,y,z)     unused in this shader.
attribute vec4 in_Colour;                    // (r,g,b,a)
attribute vec2 in_TextureCoord;              // (u,v)

varying vec2 v_vTexcoord;
varying vec4 v_vColour;

void main()
{
    vec4 object_space_pos = vec4( in_Position.x, in_Position.y, in_Position.z, 1.0);
    gl_Position = gm_Matrices[MATRIX_WORLD_VIEW_PROJECTION] * object_space_pos;
    
    v_vColour = in_Colour;
    v_vTexcoord = in_TextureCoord;
}

//######################_==_YOYO_SHADER_MARKER_==_######################@~
varying vec2 v_vTexcoord;
varying vec4 v_vColour;

uniform vec2  dimension;
uniform vec2  position;
uniform float scale;
uniform int   iteration;

///////////////////// PERLIN START /////////////////////

float random  (in vec2 st) { return fract(sin(dot(st.xy, vec2(12.9898, 78.233))) * 43758.5453123); }
vec2  random2 (in vec2 st) { float a = random(st); return vec2(cos(a), sin(a)); }

float noise (in vec2 st) {
    vec2 i = floor(st);
    vec2 f = fract(st);
    vec2 u = f * f * (3.0 - 2.0 * f);

	float lerp1 = mix(dot(f - vec2(0.0, 0.0), random2(i + vec2(0.0, 0.0))), dot(f - vec2(1.0, 0.0), random2(i + vec2(1.0, 0.0))), u.x);
    float lerp2 = mix(dot(f - vec2(0.0, 1.0), random2(i + vec2(0.0, 1.0))), dot(f - vec2(1.0, 1.0), random2(i + vec2(1.0, 1.0))), u.x);
    
    return mix(lerp1, lerp2, u.y);
}

float perlin ( vec2 pos, int iteration ) {
	float amp = pow(2., float(iteration) - 1.) / (pow(2., float(iteration)) - 1.);
    float n   = 0.;
	
	for(int i = 0; i < iteration; i++) {
		n += noise(pos) * amp;
		
		amp *= .5;
		pos *= 2.;
	}
	
	return n;
}

///////////////////// PERLIN END /////////////////////

void main() {
	vec2 ntx = v_vTexcoord * vec2(1., dimension.y / dimension.x);
    vec2 pos = position + ntx * scale;
	float n  = perlin(pos, iteration);
	
    gl_FragColor = vec4(vec3(n), 1.0);
}