CODEWITHSUNDEEP
actionscript-3flashbitmapdata
Bemmu
Bemmu

Reputation: 18247

Smooth scrolling on Flash AS3

Is it possible to do completely smooth scrolling in Flash (ActionScript 3)? In the following test I am creating a bitmap consisting of random noise, then moving it to the left periodically. I have no heavy tasks running in the background. What I am looking for is smoothness that would be on par with my Amiga 500 from 1987 :-)

package {
    import flash.display.*;
    import flash.events.TimerEvent;
    import flash.utils.Timer;

    public class Game extends Sprite {
        var noiseBitmap;

        public function Game() {
            var noiseBitmapData = new BitmapData(stage.stageWidth * 3, stage.stageHeight);
            noiseBitmapData.noise(0, 0, 255, 7, true);
            noiseBitmap = new Bitmap(noiseBitmapData);
            addChild(noiseBitmap);

            var t = new Timer(1000/30, 999999);
            t.addEventListener("timer", function (e:TimerEvent) {
                noiseBitmap.x--;
            });
            t.start();
        }
    }
}

The "rendering code" takes <1 millisecond to run on my computer (2.4 GHz Mac), but still the movement will occasionally get stuck for a frame or two, making the movement appear jerky.

FPS is set to 30 in Flash. I have tried running it both using "test movie" and in the browser (Chrome). Target is Flash Player 11.2. I have also tried calling e.updateAfterEvent() to force a redraw. I have Also played around setting the delay and FPS to slightly different values, but no improvement.

This is different from not smooth scrolling in AS3 because I am already using a BitmapData. Also I have tried using the ENTER_FRAME event instead of a timer as suggested in a reply to that question, but it did not help.

Upvotes: 0

Views: 1423

Answers (2)

Will Kru
Will Kru

Reputation: 5212

I suggest you try out Greensock's TweenLite. It is a highly optimized engine to do all sorts of tweening through code and is available for AS2 and AS3. You can find it here.

Walkietokyo's solution is still frame based and would not eliminate the issues you run into. Instead use time-based animation (which TweenLite actually implements). For more info refer to this article.

Upvotes: 3

david.emilsson
david.emilsson

Reputation: 2331

When using a timer, you will not be exactly synced with the frame rate. As you mention, the frame rate fluctuates a little making your timer sometimes fire twice during one frame or skipping a frame. To be sure to be more in sync with the frame rate, you should listen to the Event.ENTER_FRAME event.

An example:

this.addEventListener(Event.ENTER_FRAME, updateFrame);

⋮

function updateFrame(e:Event):void {
    noiseBitmap.x--;
}

Upvotes: 3

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