#define c1 vec3(1.,0.5,1.5)

vec2 triangle_wave(vec2 a,float scale){
    return abs(fract((a+c1.xy)*scale)-.5);
}

void mainImage( out vec4 fragColor, in vec2 fragCoord )
{
    fragColor = vec4(0.0);
    vec3 col = vec3(0.);
    float t1 = 2.;
    vec2 uv = (fragCoord)/iResolution.y/t1/2.0;
    uv += (iTime+8.)/vec2(2.0,3.0)/t1/8.0;
    float scale = c1.z;
    vec2 t2 = vec2(0.);
    vec2 t3 = vec2(0.);
    //float s1 = 1.;
    for(int k = 0; k < 12; k++){
        vec2 uv1 = uv;
        uv -= (t2.yx);
        t2 = triangle_wave(uv.yx+.5,scale).yx/2.;
        t3 = triangle_wave(uv,scale).yx;
        uv.yx = t3/1.5-t2;

        float m1 = uv.x;


        //More interesting patterns here:
        //float m1 = (uv.y-uv.x)/(1.-t2.x);
        //float m1 = (uv.y+uv.x)/2./(1.-t2.x);

        //float m1 = uv.x-uv.y;
        //float m1 = uv.y-uv.x;
        //float m1 = uv.x*float(k%2)+uv.y*float((k+1)%2);

        col.x = max(m1,col.x);
        col = abs(col.yzx-vec3(col.x*(2.125-t2.y)));
        uv /= scale+normalize(uv).x/3.;
        uv -= float(k%3)/2.;
        //uv -= float(k%3+5)/2.;


        //if(k>3) uv.x += iTime/s1/4.;
        //s1 *= scale;
        //uv /= 1.+normalize(t2).x/3.;
    }
    fragColor = vec4(col*2.,1.0);
}