Even Epicer

assets/shader_programs/test_fragment.glsl

@@ -7,17 +7,39 @@ precision mediump float;
 uniform vec2 u_resolution;
 uniform float u_time;
 
-vec3 colorA = vec3(0.149,0.141,0.912);
-vec3 colorB = vec3(1.000,0.833,0.224);
+vec3 rgb2hsb( in vec3 c ){
+    vec4 K = vec4(0.0, -1.0 / 3.0, 2.0 / 3.0, -1.0);
+    vec4 p = mix(vec4(c.bg, K.wz),
+                 vec4(c.gb, K.xy),
+                 step(c.b, c.g));
+    vec4 q = mix(vec4(p.xyw, c.r),
+                 vec4(c.r, p.yzx),
+                 step(p.x, c.r));
+    float d = q.x - min(q.w, q.y);
+    float e = 1.0e-10;
+    return vec3(abs(q.z + (q.w - q.y) / (6.0 * d + e)),
+                d / (q.x + e),
+                q.x);
+}
 
-void main() {
+//  Function from Iñigo Quiles
+//  https://www.shadertoy.com/view/MsS3Wc
+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);
 
-    float pct = abs(sin(u_time));
-
-    // Mix uses pct (a value from 0-1) to
-    // mix the two colors
-    color = mix(colorA, colorB, pct);
+    // We map x (0.0 - 1.0) to the hue (0.0 - 1.0)
+    // And the y (0.0 - 1.0) to the brightness
+    color = hsb2rgb(vec3(st.x,1.0,st.y));
 
     gl_FragColor = vec4(color,1.0);
 }