Set a track to classic envelope, turn on looping, infinite repeats.
Load up a sample, set loop start to beginning of sample.
Trigger sample. As sample loops, adjust loop start poiint with slider (and optionally adjust sample end with slider).
As soon as loop start equals sample end, sound cuts out and needs to be retriggered. I’d love to be able to sweep loop start, sample end without worrying if sound stops.
Suggestion - if the playback engine cannot handle a zero loop length, maybe change the computation to something like: loop_size = max(loop_end - loop_start), 5) or whatever amount of samples works to keep the loop going.
In addition, once you start messing around with start/end/loop and then you turn loop off (B unlit) the loop will still play from the last start point until you either press Shift+A to go into a menu or adjust sample end to equal loop start.
Bonus thingie - (don’t fix it) - if you are looping a part of a sample and press F7 to reverse, it only reverses that part that is looping, so by adjusting the start/end/loop points you can reverse parts of a longer sample and then flip the whole thing if you widen the start/end out to the whole sample.