This question is related to ActionScript 3.0 and Flash CS6
I am trying to make an object shake a bit in a certain for some seconds. I made it a "movieclip" and made this code:
import flash.events.TimerEvent;
var Machine_mc:Array = new Array();
var fl_machineshaking:Timer = new Timer(1000, 10);
fl_machineshaking.addEventListener (TimerEvent.TIMER, fl_shakemachine);
fl_machineshaking.start ();
function fl_shakemachine (event:TimerEvent):void {
for (var i = 0; i < 20; i++) {
Machine.x += Math.random() * 6 - 4;
Machine.y += Math.random() * 6 - 4;
}
}
When testing the movie I get multiple errors looking exactly like this one:
TypeError: Error #1009: Cannot access a property or method of a null object reference.
at Historieoppgave_fla::MainTimeline/fl_shakemachine()
at flash.utils::Timer/_timerDispatch()
at flash.utils::Timer/tick()
Also, the object doesnt shake, but it moves steadily upwards to the left a bit every tick.
To the point: I wish to know how I stop the script after the object is not in the stage/scene anymore and also how to make it shake around, as I do not see what is wrong with my script, please help, thank you ^_^
AStupidNube brought up a great point about the original position. So adding that to shaking that should be a back and forth motion, so don't rely on random values that may or may not get you what you want. Shaking also has a dampening effect over time, so try something like this:
Link to working code
• http://wonderfl.net/c/eB1E - Event.ENTER_FRAME based
• http://wonderfl.net/c/hJJl - Timer Based
• http://wonderfl.net/c/chYC - Event.ENTER_FRAME based with extra randomness
**1 to 20 shaking items Timer Based code - see link above for ENTER_FRAME code••
package {
import flash.display.Sprite;
import flash.events.Event;
import flash.events.MouseEvent;
import flash.events.TimerEvent;
import flash.geom.Point;
import flash.text.TextField;
import flash.utils.Timer;
public class testing extends Sprite {
private var shakeButton:Sprite;
private var graphic:Sprite;
private var shakerPos:Array;
private var shakers:Array;
private var numShakers:int = 20;
private var dir:int = 1;
private var displacement:Number = 10;
private var shakeTimer:Timer;
public function testing() {
this.shakers = new Array();
this.shakerPos = new Array();
this.addEventListener(Event.ADDED_TO_STAGE, this.init);
}
private function init(e:Event):void {
this.stage.frameRate = 30;
this.shakeTimer = new Timer(33, 20);
this.shakeTimer.addEventListener(TimerEvent.TIMER, this.shake);
this.graphics.beginFill(0x333333);
this.graphics.drawRect(0,0,this.stage.stageWidth, this.stage.stageHeight);
this.graphics.endFill();
this.createShakers();
this.shakeButton = this.createSpriteButton("Shake ");
this.addChild(this.shakeButton);
this.shakeButton.x = 10;
this.shakeButton.y = 10;
this.shakeButton.addEventListener(MouseEvent.CLICK, this.shakeCallback);
}
private function createSpriteButton(btnName:String):Sprite {
var sBtn:Sprite = new Sprite();
sBtn.name = btnName;
sBtn.graphics.beginFill(0xFFFFFF);
sBtn.graphics.drawRoundRect(0,0,80,20,5);
var sBtnTF:TextField = new TextField();
sBtn.addChild(sBtnTF);
sBtnTF.text = btnName;
sBtnTF.x = 5;
sBtnTF.y = 3;
sBtnTF.selectable = false;
sBtn.alpha = .5;
sBtn.addEventListener(MouseEvent.MOUSE_OVER, function(e:Event):void { sBtn.alpha = 1 });
sBtn.addEventListener(MouseEvent.MOUSE_OUT, function(e:Event):void { sBtn.alpha = .5 });
return sBtn;
}
private function createShakers():void {
var graphic:Sprite;
for(var i:int = 0;i < this.numShakers;i++) {
graphic = new Sprite();
this.addChild(graphic);
graphic.graphics.beginFill(0xFFFFFF);
graphic.graphics.drawRect(0,0,10,10);
graphic.graphics.endFill();
// add a 30 pixel margin for the graphic
graphic.x = (this.stage.stageWidth-60)*Math.random()+30;
graphic.y = (this.stage.stageWidth-60)*Math.random()+30;
this.shakers[i] = graphic;
this.shakerPos[i] = new Point(graphic.x, graphic.y);
}
}
private function shakeCallback(e:Event):void {
this.shakeTimer.reset();
this.shakeTimer.start();
}
private function shake(e:TimerEvent):void {
this.dir *= -1;
var dampening:Number = (20 - e.target.currentCount)/20;
for(var i:int = 0;i < this.numShakers;i++) {
this.shakers[i].x = this.shakerPos[i].x + Math.random()*10*dir*dampening;
this.shakers[i].y = this.shakerPos[i].y + Math.random()*10*dir*dampening;
}
}
}
}
Now this is a linear dampening, you can adjust as you see fit by squaring or cubing the values.