mep

learning/PixelSpirit/the_empress.frag

@@ -0,0 +1,36 @@
+#ifdef GL_ES
+precision mediump float;
+#endif
+uniform vec2 u_resolution;
+uniform vec2 u_mouse;
+uniform float u_time;
+
+#define PI 3.14159265359
+
+const vec3 uAColor = vec3(.5,.5,.5);
+const vec3 uBColor = vec3(.5,.5,.5);
+const vec3 uCColor = vec3(1.,1.,1.);
+const vec3 uDColor = vec3(.0,.33,.67);
+
+//get colors from http://dev.thi.ng/gradients/
+vec3 cosPalette(float t) { return uAColor + uBColor*cos(6.28318*(uCColor*t+uDColor)); }
+
+float fill(float x, float size) { return 1.-step(size, x); }
+
+float polySDF(vec2 st, float angles) {
+  st = st*2.-1.;
+  float a = atan(st.x,st.y)+PI;
+  float r = length(st);
+  float v = (2.*PI)/angles;
+  return cos(floor(.5+a/v)*v-a)*r;
+}
+
+void main() {
+  vec2 st = gl_FragCoord.xy/u_resolution;
+  vec3 color = vec3(0.0,0.0,0.0);
+  float alpha = 1.0;
+  color += fill(polySDF(st, 5),.3);
+  
+
+  gl_FragColor = vec4(color, alpha);
+}