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);
+}

utilities/inigo.glsl

@@ -0,0 +1,27 @@
+// Translation (from C) of utility functions Inigo Quilez
+// explains in http://www.iquilezles.org/www/articles/functions/functions.htm
+float almostIdentity(float x, float m, float n) {
+    if(x > m) return x;
+
+    float a = 2.*n - m;
+    float b = 2.0*m - 3.0*n;
+    float t = x/m;
+
+    return (a*t + b)*t*t + n;
+}
+
+float impulse(float k, float x) {
+    float h = k * x;
+    return h*exp(1.0-h);
+}
+
+float cubic_pulse(float c, float w, float x) {
+    x = abs(x - c);
+    if(x > w) return .0;
+    x /= w;
+    return 1.0 - x*x*(3.0-2.0*x);
+}
+
+float parabola(float x, float k) {
+    return pow(4.0*x*(1.0-x), k);
+}

weird/psychedelic_stars.glsl

@@ -0,0 +1,30 @@
+#ifdef GL_ES
+precision mediump float;
+#endif
+
+#define TAU 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(sin(u_time*0.5), cos(u_time*0.5))-st);
+    float angle = atan(toCenter.y,toCenter.x)*u_time*3.0;
+    float radius = length(toCenter)*2.0;
+
+    color = hsb2rgb(vec3((angle/TAU)+0.5,radius,1.0));
+
+    gl_FragColor = vec4(color,1.0);
+}