rename zyklus

packages/core/zyklus.mjs

@@ -0,0 +1,49 @@
+// will move to https://github.com/felixroos/zyklus
+// TODO: started flag
+
+function createClock(
+  getTime,
+  callback, // called slightly before each cycle
+  duration = 0.05, // duration of each cycle
+  interval = 0.1, // interval between callbacks
+  overlap = 0.1, // overlap between callbacks
+) {
+  let tick = 0; // counts callbacks
+  let phase = 0; // next callback time
+  let precision = 10 ** 4; // used to round phase
+  let minLatency = 0.01;
+  const setDuration = (setter) => (duration = setter(duration));
+  overlap = overlap || interval / 2;
+  const onTick = () => {
+    const t = getTime();
+    const lookahead = t + interval + overlap; // the time window for this tick
+    if (phase === 0) {
+      phase = t + minLatency;
+    }
+    // callback as long as we're inside the lookahead
+    while (phase < lookahead) {
+      phase = Math.round(phase * precision) / precision;
+      phase >= t && callback(phase, duration, tick);
+      phase < t && console.log('TOO LATE', phase); // what if latency is added from outside?
+      phase += duration; // increment phase by duration
+      tick++;
+    }
+  };
+  let intervalID;
+  const start = () => {
+    clear(); // just in case start was called more than once
+    onTick();
+    intervalID = setInterval(onTick, interval * 1000);
+  };
+  const clear = () => intervalID !== undefined && clearInterval(intervalID);
+  const pause = () => clear();
+  const stop = () => {
+    tick = 0;
+    phase = 0;
+    clear();
+  };
+  const getPhase = () => phase;
+  // setCallback
+  return { setDuration, start, stop, pause, duration, interval, getPhase, minLatency };
+}
+export default createClock;