basic: added nightsky; utilities: added random

basic/nightsky.glsl

@@ -0,0 +1,30 @@
+#ifdef GL_ES
+precision mediump float;
+#endif
+
+#define PI 3.14159265358979323846
+
+uniform vec2 u_resolution;
+uniform vec2 u_mouse;
+uniform float u_time;
+
+float random (in vec2 _st) { 
+    return fract(sin(dot(_st.xy,
+                         vec2(12.9898,78.233)))*
+        43758.5453123);
+}
+
+float line(vec2 st, float pct) {
+  return  smoothstep( pct-0.02, pct, st.y) -
+          smoothstep( pct, pct+0.02, st.y);
+}
+
+void main() {
+    vec2 st = gl_FragCoord.xy/u_resolution.xy;
+
+    float color = 0.;
+
+    color = line(st, random(st));
+
+    gl_FragColor = vec4(vec3(color),1.0);
+}

utilities/random.glsl

@@ -0,0 +1,5 @@
+float random(vec2 st) {
+    return fract(sin(dot(st.xy,
+                         vec2(12.9898,78.233)))*
+        43758.5453123);
+}