I was tinkering with some GLSL shaders in Processing, and I needed a way to visualize a value that smoothly changes from 0 to 1, showing a lot more than the 256 levels of gray that you’d normally see. So I wrote a little pseudocolor function that spirals through colorspace from black to white, hitting various hues along the way. It’s fun, and pretty, and very rungy-chungy, so I thought I’d post it here.

vec4 pseudo3(float val) {float reps = 20.0;
float pi = 3.14159256;
float bright = val;
float con = 0.25 – 0.20 * cos(val * pi * 2.0);
float sat = 0.66 – 0.25 * cos(val * pi * 2.0);

return vec4(sin(val*pi*reps)*con+bright,
sin(val*pi*reps – pi*0.663 * sat)*con+bright,
sin(val*pi*reps – pi*1.333 * sat)*con+bright,
1.0);
}