fpsCtrl.js

export function FpsCtrl(fps, callback) {

    var delay = 1000 / fps,
        time = null,
        frame = -1,
        tref

    function loop(timestamp) {
        if (time === null) time = timestamp
        var seg = Math.floor((timestamp - time) / delay)
        if (seg > frame) {
            frame = seg
            callback({
                time: timestamp,
                frame: frame
            })
        }
        tref = requestAnimationFrame(loop)
    }

    this.isPlaying = false

    this.frameRate = function(newfps) {
        if (!arguments.length) return fps
        fps = newfps
        delay = 1000 / fps
        frame = -1
        time = null
    }

    this.start = function() {
        if (!this.isPlaying) {
            this.isPlaying = true
            tref = requestAnimationFrame(loop)
        }
    }

    this.pause = function() {
        if (this.isPlaying) {
            cancelAnimationFrame(tref)
            this.isPlaying = false
            time = null
            frame = -1
        }
    }
}