Creation of a Flash Stabilize! clone using Box2D – part 4

package {
	import flash.display.Sprite;
	import flash.events.Event;
	import flash.events.MouseEvent;
	import Box2D.Dynamics.*;
	import Box2D.Collision.*;
	import Box2D.Collision.Shapes.*;
	import Box2D.Common.Math.*;
	public class stabilize extends Sprite {
		public var m_sprite: Sprite = new Sprite();
		public var m_world:b2World;
		// the_crate is the crate sprite
		public var the_crate:crate=new crate();
		// next_crate
		public var next_crate:crate=new crate();
		// droppable_area is the sprite representing the area your mouse
		// must overlap to drop a crate
		public var droppable_area:drop_area = new drop_area();
		// this is the weight of the current crate I am dropping
		public var cur_drop:int=Math.ceil(Math.random()*9);
		// this is the color of the current crate I am dropping
		public var cur_color:int=Math.ceil(Math.random()*5);
		// weight and color of "next" crate
		public var next_drop:int=Math.ceil(Math.random()*9);
		public var next_color:int=Math.ceil(Math.random()*5);
		// this is my custom contact listener class
		public var contact_listener=new custom_contact_listener();
		// the progressive number just keep track of dropped crates and
		// assign an unique number to each of them
		public var progressive:int=1;
		//
		public function stabilize() {
			var gravity:b2Vec2=new b2Vec2(0,9.8);
			var worldAABB:b2AABB = new b2AABB();
			worldAABB.lowerBound.Set(-1000,-1000);
			worldAABB.upperBound.Set(1000,1000);
			m_world=new b2World(worldAABB,gravity,true);
			// adding the contact listener
			m_world.SetContactListener(contact_listener);
			m_sprite = new Sprite();
			addChild(m_sprite);
			addChild(droppable_area);
			addChild(the_crate);
			// assigning the crate current weight and color
			the_crate.weight.text=cur_drop.toString();
			the_crate.gotoAndStop(cur_color);
			addChild(next_crate);
			// assigning "next" crate weight and color
			next_crate.weight.text=next_drop.toString();
			next_crate.gotoAndStop(next_color);
			next_crate.x=250;
			next_crate.y=385;
			debug_draw();
			AddBox(250/30,350/30,10/30,10/30,0,false);
			AddBox(250/30,350/30,200/30,10/30,20,false);
			addEventListener(Event.ENTER_FRAME,Update);
			stage.addEventListener(MouseEvent.MOUSE_DOWN,mousePressed);
			stage.addEventListener(MouseEvent.MOUSE_MOVE,mouseMoved);
		}
		public function mousePressed(e:MouseEvent) {
			// look at hitTestPoint... the final true value says it's going to to check against the actual pixels
			// instead of the bounding box
			if (droppable_area.hitTestPoint(mouseX,mouseY,true)) {
				// notice the cur_drop parameter, I am passing the weight of the current crate to the AddBox function
				AddBox(mouseX/30,mouseY/30,0.5,0.5,cur_drop,true);
			}
		}
		public function mouseMoved(e:MouseEvent) {
			the_crate.x=mouseX;
			the_crate.y=mouseY;
			if (droppable_area.hitTestPoint(mouseX,mouseY,true)) {
				the_crate.alpha=1;
			} else {
				the_crate.alpha=0.5;
			}
		}
		// function AddBox
		// px: x position
		// py: y position
		// _halfwidth: half of the box width
		// _halfheight: half of the box height
		// density: density of the box (0: static)
		// is_crate: if true, it's a crate (and you should render the proper movieclip
		public function AddBox(px:Number,py:Number,_halfwidth:Number,_halfheight:Number,density:Number,is_crate:Boolean) {
			var bodyDef:b2BodyDef = new b2BodyDef();
			bodyDef.position.Set(px,py);
			var boxDef:b2PolygonDef = new b2PolygonDef();
			boxDef.SetAsBox(_halfwidth,_halfheight);
			boxDef.density=density;
			boxDef.friction=0.3;
			boxDef.restitution=0.2;
			if (is_crate) {
				bodyDef.userData = new crate();
			}
			var body:b2Body=m_world.CreateBody(bodyDef);
			body.CreateShape(boxDef);
			body.SetMassFromShapes();
			if (is_crate) {
				addChild(bodyDef.userData);
				// assigning current weight and color to the Box2D sprite bound to the box I created
				bodyDef.userData.weight.text=cur_drop.toString();
				// collz is the text that will count the number of collisions
				bodyDef.userData.collz.text=0;
				// assigning the progressive number to the crate...
				bodyDef.userData.prog=progressive;
				// ... and incrementing it for next one
				progressive++;
				bodyDef.userData.gotoAndStop(cur_color);
				// updating current weight and color with the next ones
				cur_drop=next_drop;
				cur_color=next_color;
				// changing current crate movieclip according to its weight and color
				the_crate.weight.text=cur_drop.toString();
				the_crate.gotoAndStop(cur_color);
				// calculating next crate weight and color
				next_drop=Math.ceil(Math.random()*9);
				next_color=Math.ceil(Math.random()*5);
				// updating next crate movieclip according to its weight and color
				next_crate.weight.text=next_drop.toString();
				next_crate.gotoAndStop(next_color);
			}
		}
		public function Update(e:Event) {
			var crate_num:int;
			m_world.Step(1/30,10);
			for (var bb:b2Body = m_world.m_bodyList; bb; bb = bb.m_next) {
				if (bb.m_userData is Sprite) {
					bb.m_userData.x=bb.GetPosition().x*30;
					bb.m_userData.y=bb.GetPosition().y*30;
					bb.m_userData.rotation = bb.GetAngle() * (180/Math.PI);
				}
			}
		}
		public function debug_draw() {
			var dbgDraw:b2DebugDraw = new b2DebugDraw();
			var dbgSprite:Sprite = new Sprite();
			m_sprite.addChild(dbgSprite);
			dbgDraw.m_sprite=m_sprite;
			dbgDraw.m_drawScale=30;
			dbgDraw.m_alpha=1;
			dbgDraw.m_fillAlpha=0.5;
			dbgDraw.m_lineThickness=1;
			dbgDraw.m_drawFlags=b2DebugDraw.e_shapeBit;
			m_world.SetDebugDraw(dbgDraw);
 
		}
	}
}

package {
	//
	import Box2D.Collision.*;
	import Box2D.Collision.Shapes.*;
	import Box2D.Dynamics.Contacts.*;
	import Box2D.Dynamics.*;
	import Box2D.Common.Math.*;
	import Box2D.Common.*;
	//
	public class custom_contact_listener extends b2ContactListener {
		// this array will hold all collisions among crates
		var collz:Array=new Array;
		//
		public override function Add(point:b2ContactPoint):void {
		}
		//
		public override function Persist(point:b2ContactPoint):void {
			// if the bodies that collided have an userData different from null,
			// then we can say they are crates.
			// So, if collided bodies are crates...
			if (point.shape1.GetBody().GetUserData()!=null&&point.shape2.GetBody().GetUserData()!=null) {
				// if both crates have the same color...
				if (point.shape1.GetBody().GetUserData().currentFrame==point.shape2.GetBody().GetUserData().currentFrame) {
					// getting progressive number of both crates
					var num1:int=point.shape1.GetBody().GetUserData().prog;
					var num2:int=point.shape2.GetBody().GetUserData().prog;
					// if the collision array of the num1-th crate does not exists...
					if (collz[num1]==undefined) {
						// create it
						collz[num1]=new Array;
						// populate it with the num2-th crate
						collz[num1].push(num2);
					} else {
						// if already exists, check if the num2-th crate already exists...
						if (collz[num1].indexOf(num2)==-1) {
							// if not, add it just like before
							collz[num1].push(num2);
						}
					}
					// same thing for the collision array of the num2-th crate
					if (collz[num2]==undefined) {
						collz[num2]=new Array  ;
						collz[num2].push(num1);
					} else {
						if (collz[num2].indexOf(num1)==-1) {
							collz[num2].push(num1);
						}
					}
					// updating the number of collision shown in both crates
					point.shape1.GetBody().GetUserData().collz.text=collz[num1].length;
					point.shape2.GetBody().GetUserData().collz.text=collz[num2].length;
				}
			}
		}
		//
		public override function Remove(point:b2ContactPoint):void {
		}
		//
		public override function Result(point:b2ContactResult):void {
		}
	}
}