diff --git a/13/fractal-tile.frag b/13/fractal-tile.frag
index 8b61b89..2d183b2 100644
--- a/13/fractal-tile.frag
+++ b/13/fractal-tile.frag
@@ -1,19 +1,34 @@
+// Author @patriciogv - 2015
+// http://patriciogonzalezvivo.com
+
 #ifdef GL_ES
 precision mediump float;
 #endif
-                
+
+#define PI 3.14159265359
+#define TWO_PI 6.28318530718
+
 uniform vec2 u_resolution;
 uniform float u_time;
 
-float random(in vec2 st){ return fract(sin(dot(st.xy ,vec2(12.9898,78.233))) * 43758.5453); }
+float random(vec2 st){ return fract(sin(dot(st.xy ,vec2(12.9898,78.233))) * 43758.5453); }
 
-vec2 tileFractal(vec2 st) {
-	vec2 f = fract(st);
-    vec2 i = floor(st);
-    
-    return fract(st*pow(2.,floor(random(i)*5.)));
+vec2 tileFractal(vec2 st, int scale, int levels) {
+    for (int i = 0; i < levels; i++){
+        st *= float(scale);
+        vec2 i_st = floor(st);
+        st = fract(st*pow(2., floor(2.*random(i_st))) );
+    }
+    return st;
 }
 
+// vec2 tileFractal(vec2 st) {
+//     st *= 4.;
+//     vec2 i_st = floor(st);
+//     st = fract(st*pow(2., floor(4.*random(i_st))) );
+//     return st;
+// }
+
 float circle(vec2 st, float radius){
     vec2 pos = vec2(0.5)-st;
     radius *= 0.75;
@@ -27,19 +42,26 @@ float box(vec2 st, vec2 size){
     return uv.x*uv.y;
 }
 
+float shapeDF(vec2 st, int N){
+    st = st *2.-1.;
+    float a = atan(st.x,st.y)+PI;
+    float r = TWO_PI/float(N);
+    return cos(floor(.5+a/r)*r-a)*length(st);
+}
+
 void main() {
 	vec2 st = gl_FragCoord.xy/u_resolution;
     vec3 color = vec3(0.0);
 
-	st *= 3.;
-    st = tileFractal(st);
+    st = tileFractal(st,3,2);
     
    	float pct = 0.;
     pct = circle(st,.999);
    	// pct = box(st,vec2(.95));
+    // pct = step(.15,1.-shapeDF(st.yx,6))-step(.3,1.-shapeDF(st.yx,6));
 
-    color.rg = st;
-    color.rgb = vec3(1.)*pct;
+    // color.rg = st;
+    color.rgb += vec3(1.)*pct;
 
     gl_FragColor = vec4(color,1.);
 }
\ No newline at end of file