function* timer(totalFrames = 120, fps = 60) {
const step = fps / 60;
let frame = 0;
while (true) {
frame = frame < totalFrames ? frame + step : 0;
const frameFloor = Math.floor(frame);
const playhead = frameFloor / totalFrames;
yield {
frame: frameFloor,
fps,
totalFrames,
playhead
};
}
}