2D rotation matrix. Returns a mat2 so you can rotate a coordinate plane in place with p.xy *= rot(a), rather than transforming a point like _rotate does.
Synesthesia already ships _rotate(uv, angle), which rotates a vec2 and hands it
back. So why would you need rot()?
_rotate transforms a point, and often what you want is the matrix itself.
mat2 rot(float a) {
float s = sin(a);
float c = cos(a);
return mat2(c, s, -s, c);
}Round-trip between cartesian and polar (angle, radius) coordinates — the inverse-included counterpart to the built-in _toPolar.
mix, smoothstep and normalized sin re-implemented for script.js, where the GLSL builtins you're used to don't exist.
Approximate float equality, comparing computed values without exact-match fragility.