A preset is recalled in a pattern with command 00: in the Cmd column, 00 and the preset's number, as 00 0003.
main() that sets gl_FragColor. It runs a moment after you stop typing, and a mistake shows below with its line marked, while the built-in picture keeps running.
Uniforms: R size, T seconds, BEAT beats, HITS all hits 0..1, NL lanes, C1 C2 colours, LANE[16] (hit, pitch, vel, held). Look-ups: hit("kick") pitch("acid") vel(2) held("pad") hits() by lane name or number from 0; cell("kick", dx) the pattern dx ticks from the playhead (-8 to +23). kn("name", start, low, high) is a number the patterns can move: press expose on a number in the Knobs panel and it becomes one, with a column of that name in the hatched shader lane (0 is low, FF is high).