Question: smoke originating at bottom of full document height? about smoke.js HOT 1 CLOSED

<canvas id="canvas"></canvas>
<script src="smoke.js"></script>
<script>
    var canvas = document.getElementById('canvas')
    var ctx = canvas.getContext('2d')
    canvas.width = 1000
    canvas.height = 4000

    var party = smokemachine(ctx)

    party.start()

    party.addsmoke(500,3500,10) 

</script>