testing shader fragments

2d_thing.frag

@@ -0,0 +1,50 @@
+#ifdef GL_ES
+    precision mediump float;
+#endif
+
+const float PI = 3.14159265;
+uniform vec2 u_resolution;
+uniform float u_time;
+
+vec3 palette(float t)  {
+ vec3 a = vec3(0.5, 0.5, 0.5);
+ vec3 b = vec3(1.0, 1.0, 1.0);
+ vec3 c = vec3(1.0, 1.0, 1.0);
+ vec3 d = vec3(0.0, 0.6666, 0.3333);
+ return a + b * cos(6.28318 * (c*t+d));
+}
+ 
+
+mat2 rotate(float angle){
+    return mat2(cos(angle), -sin(angle), sin(angle), cos(angle));
+}
+
+float polygon(vec2 position, float radius, float sides){
+    float a = atan(position.x, position.y);
+    float slice = PI * 2.0 / sides;
+    return 1. - step(radius, cos(floor(0.5 + a / slice) * slice - a) * length(position));
+}
+
+
+float star(vec2 position, float radius, float sides){
+    float a = atan(position.x, position.y);
+    float slice = PI * 2. / sides;
+    return 1. - step(radius, cos(floor(-2.0 + a / slice) * slice - a));
+}
+
+
+void main() {
+    vec2 uv = (gl_FragCoord.xy * 2. - u_resolution.xy) / u_resolution.y;
+    vec3 color = vec3(0.08, 0.22, 0.39);
+    vec3 mixer = vec3(0.);
+    for(float i = 1.; i < 3.; i++){
+        vec2 translate = uv;
+        translate *= rotate(i*1.4/5.); // + u_time);
+        float sides = 11.;
+        mixer += vec3(star(translate, 0.06, sides))*vec3(0.5725, 0.8275, 0.9451)*(i*0.7)*0.2;        
+    }
+
+    color = mix( color, mixer, 0.5);   
+    // color = max(color, polygon(uv, 0.3, 6.)),
+    gl_FragColor = vec4(color, 1.0);    
+}