manewcActionscript Snippets

[AS 3] Simple Hit Test with hitTestPoint Method

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DisplayObject.hitTestPoint(x:Number, y:Number, shapeFlag:Boolean = false)

This method is great for testing intersections with an X,Y point of the stage. Ideally you would use this with small objects to allow for a more realistic hit test.

I used my circle class from earlier.

package {
     import flash.display.Sprite;  

     public class Circle extends Sprite {
        private var radius:Number;
        private var color:uint;

		private var xcircle:Number;
		private var ycircle:Number;

		public function Circle(radius:Number=20, color:uint=0x336699, xcircle:Number = 10, ycircle:Number = 20) {
			this.x = xcircle;
            this.y = ycircle;
			this.radius = radius;
			this.color = color;

            draw();
		}

		public function draw(){
			graphics.beginFill(color);
            graphics.drawCircle(0, 0, radius);
            graphics.endFill();
		}
	}
}

Now my document class for the hitTestObject method

package {
     import flash.display.Sprite;
	 import flash.events.Event;

     public class HitTestPoint extends Sprite {
		private var circle:Circle;
		private var circle2:Circle;

		private var radius:Number;
		private var color:uint;

		private var xcircle:Number;
		private var ycircle:Number;

		public function HitTestPoint(){
			init()
		}

		public function init(){
			// CIRCLE 1
			// draw the first circle and center it on the stage
			circle = new Circle(30,0x333333,stage.stageWidth/2, stage.stageHeight/2);
			// display the circle
			addChild(circle);
			circle.startDrag(true);

			// CIRCLE 2
			circle2 = new Circle(4,0x000000,200,200);
			// display the circle
			addChild(circle2);
			circle2.alpha = 10;

			// create the listeners
			addEventListener(Event.ENTER_FRAME, testHit);
		}

		private function testHit(e:Event):void
		{
			// hit point area is x = 200 and y = 200
			if(circle.hitTestPoint(200, 200, false))
				trace ("HIT !!!!");
		}
	}
}

Wednesday, January 16th, 2008 at 12:28 pm and is filed under Actionscript 3, HitTest Methods. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.