Emanuele Feronato

String Avoider Starling prototype using Starling-Extension-Graphics library and Flash graphic API methods

Talking about String Avoider game, Actionscript 3, Flash, Game development and Starling.

One of the things I was missing the most in Starling framework is I can’t access to AS3 graphic API. I wanted do do a quick port of Stringy game but since it’s mostly based upon graphic API, it seemed impossible… I wasn’t satisfied of my iPhone String Avoider prototype with Adobe Flash Professional CS5.5 so I dropped the project until I found Starling-Extension-Graphics which adds a suite of graphics primitives such as Planes, Fills and Strokes.

With this awesome library I was finally able to make a decent port of the string avoider prototype, have a look:

Main class:

package {
	
	import flash.display.Sprite;
	import starling.core.Starling;
	
	[SWF(width="640",height="480",frameRate="60",backgroundColor="#ffffff")]
	
	public class Main extends Sprite {
		private var _starling:Starling;
		public function Main() {
			_starling=new Starling(Game,stage);
			_starling.showStats=true;
			_starling.start();
		}
	}
}

Game class:

package {
	import flash.geom.Point;	
	import starling.display.Sprite;
	import starling.events.TouchEvent;
	import starling.events.Touch;
	import starling.events.TouchPhase;
	import starling.display.Shape; // <- this belongs to Starling-Extension-Graphics
	public class Game extends Sprite {	
		private var tailLenght:Number=1;
		private var tailNodes:Number=300;
		// Look, I am creating shapes as if they were sprites
		private var bgShape:Shape=new Shape();
		private var tailShape:Shape=new Shape();
		private var nodes:Vector.<Point>=new Vector.<Point>();
		public function Game() {
			// same thing as the good old flash graphic class
			addChild(bgShape);
			bgShape.graphics.beginFill(0x000000);
			bgShape.graphics.drawRect(0, 0,640, 480);
			bgShape.graphics.endFill();
			addChild(tailShape);
			for (var i:Number=0; i<tailNodes; i++) {
				nodes[i]=new Point(320,240);
			}
			addEventListener(TouchEvent.TOUCH,touched);
		}
		private function touched(e:TouchEvent):void {
			// checking if we are dragging the mouse
			var mouseMoved:Touch=e.getTouch(this,TouchPhase.MOVED);
			if (mouseMoved) {
				// retrieving mouse location
				var localPos:Point=mouseMoved.getLocation(this);
				// removing and disposing old shape then creating a new one  allows us to save memory
				removeChild(tailShape,true);
				tailShape=new Shape();
				tailShape.graphics.clear();
				tailShape.graphics.lineStyle(2,0xffffff);
				tailShape.graphics.beginFill(0xffffff);
				tailShape.graphics.drawCircle(localPos.x,localPos.y,5);
				tailShape.graphics.endFill();
				tailShape.graphics.moveTo(localPos.x,localPos.y);
				nodes[0]=new Point(localPos.x,localPos.y);
				for (var i:Number=1; i<tailNodes-1; i++) {
					var nodeAngle:Number=Math.atan2(nodes[i].y-nodes[i-1].y,nodes[i].x-nodes[i-1].x);
					nodes[i]=new Point(nodes[i-1].x+tailLenght*Math.cos(nodeAngle),nodes[i-1].y+tailLenght*Math.sin(nodeAngle));
					tailShape.graphics.lineTo(nodes[i].x,nodes[i].y);
				}
				addChild(tailShape);
			}
		}
	}
}

And this is the result, running at 60fps:

Click and drag the mouse to animate the string. It runs at 60fps smoothly, so tomorrow I am porting it to my iPad and will show you both the source code and the result.

Download the source code with all needed libraries