basic: added a color spinner; utilities: added translations of inigo quilez' functions; weird: added psychedelic stars

basic/spinner.glsl

@@ -0,0 +1,31 @@
+#ifdef GL_ES
+precision mediump float;
+#endif
+
+#define TWO_PI 6.28318530718
+
+uniform vec2 u_resolution;
+uniform float u_time;
+
+vec3 hsb2rgb( in vec3 c ){
+    vec3 rgb = clamp(abs(mod(c.x*6.0+vec3(0.0,4.0,2.0),
+                             6.0)-3.0)-1.0,
+                     0.0,
+                     1.0 );
+    rgb = rgb*rgb*(3.0-2.0*rgb);
+    return c.z * mix( vec3(1.0), rgb, c.y);
+}
+
+void main(){
+    vec2 st = gl_FragCoord.xy/u_resolution;
+    vec3 color = vec3(0.0);
+
+
+    vec2 toCenter = vec2(0.5)-st;
+    float angle = atan(toCenter.y,toCenter.x);
+    float radius = length(toCenter)*2.0;
+
+    color = hsb2rgb(vec3((angle/TWO_PI)+0.5*u_time*0.35,radius,1.0/radius));
+
+    gl_FragColor = vec4(color,1.0);
+}