// Based on FabriceNeyret2 - plop 2 shader

varying vec2 v_vTexcoord;
varying vec4 v_vColour;

uniform vec2 position;
uniform vec2 scale;

uniform int   iteration;
uniform float stretch;
uniform float amplitude;

uniform int   mode;

void main() {
	vec2 pos = v_vTexcoord * scale + position;
	vec4 col = vec4(0., 0., 0., 1.);
	
    for (int i = 0; i < iteration; i++) {
    	pos += cos( pos.yx * 3. + vec2(0.0, stretch)) / 3.;
        pos += sin( pos.yx      + vec2(stretch, 0.0)) / 2.;
        pos *= amplitude;
    }
    
	if(mode == 0) col += length(mod(pos, 2.) - 1.);
	else          col.xy += abs(mod(pos, 2.) - 1.);
	
    gl_FragColor = col;
}