forked from: forked from: forked from: Box2D Magnet

by tananuka13 23 Feb 2011

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/**
 * Copyright tananuka13 ( http://wonderfl.net/user/tananuka13 )
 * MIT License ( http://www.opensource.org/licenses/mit-license.php )
 * Downloaded from: http://wonderfl.net/c/t3ns
 */

// forked from Nek's forked from: forked from: Box2D Magnet
// forked from Nek's forked from: Box2D Magnet
// forked from shapevent's Box2D Magnet
package {
    import flash.display.*;
    import flash.events.*;
    import flash.text.*;
    import com.actionsnippet.qbox.*;
    import Box2D.Common.Math.*;
    
    public class FlashTest extends MovieClip {
        
        private var sim:QuickBox2D;
        private var out:TextField;
        private var big:QuickObject;
        private var little:QuickObject;
        private var little2:QuickObject;
        private var dir:b2Vec2;
        private var littles:Vector.<QuickObject> = new Vector.<QuickObject>();
        public function FlashTest() {
            
            sim = new QuickBox2D(this);
            
            sim.gravity = new b2Vec2(0,10);
            
            sim.createStageWalls();
            
            big = sim.addCircle({x: 7, y: 7, radius: 2, friction:5});
            
            addCircle();
            addPoly();
            addCircle();
            addPoly();
            addCircle();
            addPoly();
            addPoly();
            addPoly();
            addPoly();
            
            
            
            
            sim.start();
            sim.mouseDrag();
            addEventListener(Event.ENTER_FRAME, onLoop);
            
            out = new TextField();
            out.x = out.y = 50;
            out.border = true;
            out.autoSize = "left";
            addChild(out);
            
            dir = new b2Vec2();
            
            
        }
        
        private function addCircle():void {
            littles.push(sim.addCircle({x : 3, y: 12, radius: 1, friction:5}));
        }
        private function addPoly():void {
            littles.push(sim.addPoly({x : 3, y: 12, friction:5}));
        }
        

        
        // this is where the magnet code happens:
        
        private function onLoop(evt:Event):void{
            for each(var little:QuickObject in littles) moveBody(little);
            
            
            big.body.SetLinearVelocity(new b2Vec2(0,0));             
        }

             
             private function moveBody(little:QuickObject):void {
                 var ang:Number = angle(big, little);
                var maxDist:Number = 100;
            
                var intensity:Number = 2;
                var currVel:b2Vec2 = little.body.GetLinearVelocity();
            
                dir.x = currVel.x + intensity * Math.cos(ang);
                dir.y = currVel.y + intensity * Math.sin(ang);
            
                little.body.SetLinearVelocity(dir);
             }
  
                
        private function dist(a:QuickObject, b:QuickObject):Number{
          var dx:Number = a.x - b.x;
          var dy:Number = a.y - b.y;
          
          return Math.sqrt(dx * dx + dy * dy);    
        }
        private function angle(a:QuickObject, b:QuickObject):Number{
          var dx:Number = a.x - b.x;
          var dy:Number = a.y - b.y;
          
          return Math.atan2(dy,dx);  
        }
    }
}