#ifdef GL_FRAGMENT_PRECISION_HIGH
precision highp float;
precision highp int;
#else
precision mediump float;
precision mediump int;
#endif

// Twin-prime midpoints: 4, 6, 12, 18, 30, 42, 60, ...
// We met at 18. Now we're at 30. 
// Happy Birthday, FRB! Here's to (infinitely?) many more!

uniform vec2 iResolution; // viewport resolution (in pixels)
uniform float iTime; // shader playback time (in seconds)