An FFGL source that draws a tracker's pattern editor and lets the music fill it in. The row cursor runs on the tracker's own clock, four rows a beat at the default Speed of 6, locked to the host's tempo. Each channel owns a band of Resolume's 64-bin spectrum, and an onset in that band writes a note on the current row, with its pitch from the band's peak and its volume as a Cxx effect. After row 3F the cursor wraps round and the next pass writes over the last.
This demo runs the plugin's shader in your browser, so it needs JavaScript and WebGL2. The plugin itself, its source and its downloads are on its repository.