Box2DFlashAS3 v2.1a HelloWorld

package{
package {
  /*
   * Tony Lukasavage - SavageLook.com - 8/18/2010
   * Box2DFlashAS3 2.1a HelloWorld example, minus the need for an accompanying FLA
   *
   * This the basic Box2DFlashAS3 HelloWorld.as file from the source distribution
   * with some adjustments made so that you do not need an FLA file to compile and
   * run the code.  A simple bonus for us pure AS3 guys.  Also a few minor modifications
   * are made to account for changes between version 2.0 and 2.1, like adding a type
   * for body definitions.  Finally, I threw in an click handler to toggle between
   * normal and debug drawing.
   *
   */
 
  import Box2D.Collision.*;
  import Box2D.Collision.Shapes.*;
  import Box2D.Common.Math.*;
  import Box2D.Dynamics.*;
 
  import __AS3__.vec.Vector;
 
  import com.adobe.viewsource.ViewSource;
 
  import flash.display.Sprite;
  import flash.events.Event;
  import flash.events.MouseEvent;
  import flash.geom.Matrix;
  import flash.text.TextField;
  import flash.text.TextFormat;
 
  [SWF(width="800", height="600", frameRate="30")]
  public class box2d extends Sprite
  {
    private var _world:b2World;
    private var _velocityIterations:int = 10;
    private var _positionIterations:int = 10;
    private var _timeStep:Number = 1.0 / 30.0;
    private var _showDebug:Boolean = true;
    private var _debugSprite:Sprite;
    private var _bodySprites:Vector. = new Vector.();
 
    // Box2D uses meters for measurement, AS3 uses pixels.  1 meter = 30 pixels
    public var _worldRatio:int = 30;
 
    public function box2d()
    {
      // Add event for main loop
      addEventListener(Event.ENTER_FRAME, Update, false, 0, true);
      stage.addEventListener(MouseEvent.CLICK, onClick );
 
      // add background gradient
      var bg:Sprite = new Sprite();
      var matrix:Matrix = new Matrix();
      matrix.createGradientBox(stage.stageWidth, stage.stageHeight, Math.PI/2, 0, 0);
      bg.graphics.beginGradientFill("linear", [0x9999ff, 0xffffff], [1, 1], [0, 255], matrix);
      bg.graphics.drawRect(0, 0, stage.stageWidth, stage.stageHeight);
      bg.graphics.endFill();
      addChild(bg);
 
      // Define the gravity vector
      var gravity:b2Vec2 = new b2Vec2(0.0, 10.0);
 
      // Allow bodies to sleep
      var doSleep:Boolean = true;
 
      // Construct a world object
      _world = new b2World(gravity, doSleep);
 
      // set debug draw
      var debugDraw:b2DebugDraw = new b2DebugDraw();
      _debugSprite = new Sprite();
      addChild(_debugSprite);
      debugDraw.SetSprite(_debugSprite);
      debugDraw.SetDrawScale(_worldRatio);
      debugDraw.SetFillAlpha(0.5);
      debugDraw.SetLineThickness(2);
      debugDraw.SetAlpha(1);
      debugDraw.SetFlags(b2DebugDraw.e_shapeBit | b2DebugDraw.e_jointBit);
      _world.SetDebugDraw(debugDraw);
 
      // Vars used to create bodies
      var body:b2Body;
      var bodyDef:b2BodyDef;
      var boxShape:b2PolygonShape;
      var circleShape:b2CircleShape;
 
      // Adding sprite variable for dynamically creating body userData
      var sprite:Sprite;
      var groundHeight:int = 60;
 
      sprite = new Sprite();
      sprite.graphics.lineStyle(1);
      sprite.graphics.beginFill(0x444444);
      sprite.graphics.drawRect(-stage.stageWidth/2, -groundHeight/2, stage.stageWidth, groundHeight);
      sprite.graphics.endFill();
 
      bodyDef = new b2BodyDef();
      bodyDef.type = b2Body.b2_staticBody;
      bodyDef.position.Set(stage.stageWidth / _worldRatio / 2, (stage.stageHeight - sprite.height/2) / _worldRatio);
      bodyDef.userData = sprite;
      addChild(bodyDef.userData);
 
      boxShape = new b2PolygonShape();
      boxShape.SetAsBox(sprite.width/_worldRatio/2, sprite.height/_worldRatio/2);
 
      var fixtureDef:b2FixtureDef = new b2FixtureDef();
      fixtureDef.shape = boxShape;
      fixtureDef.friction = 0.3;
      fixtureDef.density = 0; // static bodies require zero density
 
      body = _world.CreateBody(bodyDef);
      body.CreateFixture(fixtureDef);
 
      // Add some objects
      for (var i:int = 1; i < 20; i++) {
        // create generic body definition
        bodyDef = new b2BodyDef();
        bodyDef.type = b2Body.b2_dynamicBody;
        bodyDef.position.x = Math.random() * 15 + 5;
        bodyDef.position.y = Math.random() * 10;
        var rX:Number = Math.random() + 0.5;
        var rY:Number = Math.random() + 1;
        var spriteX:Number = rX * 30 * 2;
        var spriteY:Number = rY * 30 * 2;
 
        // Box
        if (Math.random() < 0.5) {
          sprite = new Sprite();
          sprite.graphics.lineStyle(1);
          sprite.graphics.beginFill(0xff6666);
          sprite.graphics.drawRect(-spriteX/2, -spriteY/2, spriteX, spriteY);
          sprite.graphics.endFill();
          bodyDef.userData = sprite;
 
          boxShape = new b2PolygonShape();
          boxShape.SetAsBox(rX, rY);
 
          fixtureDef.shape = boxShape;
          fixtureDef.density = 1.0;
          fixtureDef.friction = 0.5;
          fixtureDef.restitution = 0.2;
 
          body = _world.CreateBody(bodyDef);
          body.CreateFixture(fixtureDef);
        }
        // Circle
        else {
          sprite = new Sprite();
          sprite.graphics.lineStyle(1);
          sprite.graphics.beginFill(0x44ff44);
          sprite.graphics.drawCircle(0, 0, spriteX/2);
          sprite.graphics.endFill();
          bodyDef.userData = sprite;
 
          circleShape = new b2CircleShape(rX);
 
          fixtureDef.shape = circleShape;
          fixtureDef.density = 1.0;
          fixtureDef.friction = 0.5;
          fixtureDef.restitution = 0.2;
 
          body = _world.CreateBody(bodyDef);
          body.CreateFixture(fixtureDef);
        }
 
        _bodySprites.push(bodyDef.userData as Sprite);
        addChild(bodyDef.userData);
      }
 
      // enable view source
      ViewSource.addMenuItem(this, "srcview/index.html");
      var text:TextField = new TextField();
      text.text = "Right click to view source";
      text.setTextFormat(new TextFormat("arial", 14, 0, true));
      text.x = 20;
      text.y = 20;
      text.width = 200;
      addChild(text);
    }
 
    public function onClick(e:MouseEvent):void {
      _showDebug = !_showDebug;
      if (!_showDebug) {
        _debugSprite.graphics.clear();
      }
      for each (var sprite:Sprite in _bodySprites) {
        sprite.visible = !_showDebug;
      }
    }
 
    public function Update(e:Event):void{
      _world.Step(_timeStep, _velocityIterations, _positionIterations);
      if (_showDebug) {
        _world.DrawDebugData();
      }
 
      // Go through body list and update sprite positions/rotations
      for (var bb:b2Body = _world.GetBodyList(); bb; bb = bb.GetNext()){
        if (bb.GetUserData() is Sprite){
          var sprite:Sprite = bb.GetUserData() as Sprite;
          sprite.x = bb.GetPosition().x * 30;
          sprite.y = bb.GetPosition().y * 30;
          sprite.rotation = bb.GetAngle() * (180/Math.PI);
        }
      }
    }
  }
}