Tag: QuickBox2D

[SWF(width = 800, height = 600, frameRate = 60)]
import com.actionsnippet.qbox.*;
stage.frameRate = 60;

var sim:QuickBox2D = new QuickBox2D(this);

sim.createStageWalls();

sim.start();

var output:TextField = new TextField();
output.text = "Click anywhere to add points to a polygon. Hit any key to test.nn";
output.x = output.y = 50;
with(output) width = 300, height = 400, border = true, selectable = true, wordWrap = true, multiline = true;
addChild(output);

function display(str:*):void{
	output.appendText(str.toString() + "n");
}
								
var points:Array = [];
var poly:Shape = new Shape();
addChild(poly);

stage.addEventListener(MouseEvent.CLICK, onClick);
stage.addEventListener(KeyboardEvent.KEY_DOWN, onKeyPressed);

function onClick(evt:MouseEvent):void {
	if (points.length == 0){
		poly.graphics.beginFill(0xCCCCCC);
		poly.graphics.lineStyle(1, 0xFF0000);
		poly.graphics.moveTo(mouseX, mouseY);
	}else{
		poly.graphics.lineTo(mouseX, mouseY);
	}
	poly.graphics.drawCircle(mouseX, mouseY, 2);
	 
	points.push(mouseX / 30.0, mouseY / 30.0);
}

function onKeyPressed(evt:KeyboardEvent):void {
	 // average all points
	 var avgX:Number=0
	 var avgY:Number = 0;
	 
	 for (var i:int = 0; i<points.length; i+=2){
	     avgX += points[i];
		 avgY += points[i + 1];
	 }
	
	 avgX /= points.length/2;
	 avgY /=  points.length/2;
	 avgX = avgX;
	 avgY = avgY;
	 
	 // subtract averages and fix decimal place
	  for (i = 0; i<points.length; i+=2){
		  var yp:int = i + 1;
	      points[i] -= avgX;
		  points[yp] -= avgY;
		  points[i] = Number(points[i].toFixed(2));
		  points[yp] = Number(points[yp].toFixed(2));
	 }
	 
	 display("points array:");
	 display(points);
	 
	 try{
		 var p:QuickObject = sim.addPoly({x:avgX, y:avgY, points:points});
		 p.userData.graphics.beginFill(0xFF0000);
		 p.userData.graphics.drawCircle(0,0,5);
	 }catch(e:*){
		display("Invalid polygon data!"); 
	 }
	 
	 poly.graphics.clear();
	 points = [];
}

This snippet shows the basic concepts needed to go about creating a polygon editor for QuickBox2D. I have an unreleased editor that I use for my QuickBox2D projects, at some point I may release it… but for now I figured I’d post this extremely simplified version for people to expand on.

Have a look at the swf here…

Since this is a rather large snippet check out this demo first:

View Demo…

and here is the source:

import com.actionsnippet.qbox.*
import Box2D.Collision.Shapes.*;
import Box2D.Common.Math.*;

[SWF(width = 800, height = 600, backgroundColor = 0x000000, frameRate = 60)]

var sim:QuickBox2D = new QuickBox2D(this, {debug:true});
 
var sw:Number = stage.stageWidth / 30;
var sh:Number = stage.stageHeight / 30;
			
sim.addBox({x:sw / 2, y:sh, width:sw - 3, height:1,  density:.0})
sim.addBox({x:sw / 2, y:0, width:sw - 3, height:1,  density:.0 })
sim.addBox({x:0, y:sh / 2, width:1, height:sh ,  density:.0})  
sim.addBox({x:sw, y:sh / 2, width:1, height:sh,  density:.0})  

var slider:QuickObject = sim.addBox({x:3, y:6, width:6, height:0.25, density:0, angle:0.05});
var pusher:QuickObject = sim.addBox({x:15, y:18, width:4, height:4, density:0});

sim.setDefault({collideConnected:false, frequencyHz:10});
var anchor:QuickObject = sim.addCircle({x:3, y:2, radius:0.2, density:0});

var m0:QuickObject = sim.addBox({x:3, y:5, width:1, height:0.25, fixedRotation:true});

var j0:QuickObject = sim.addJoint({type:"distance", a:anchor.body, b:m0.body});

var m1:QuickObject = sim.addBox({x:2.5, y:9.5, width:0.25, height:6, fixedRotation:true});
var m2:QuickObject = sim.addBox({x:3.5, y:9.5, width:0.25, height:6, fixedRotation:true});

var j1:QuickObject = sim.addJoint({type:"distance", a:m0.body, b:m1.body});
var j2:QuickObject = sim.addJoint({type:"distance", a:m0.body, b:m2.body});
var j3:QuickObject = sim.addJoint({type:"distance", a:m2.body, b:m1.body});

var boxes:Array = [];
var boxNum:int = 21;
var index:int = boxNum;
var filter:b2FilterData;
var lookupQuickObject:Dictionary = new Dictionary();
for (var i:int = 0; i<boxNum; i++){
	boxes[i] = sim.addBox({x:3, y:6.3 + i * 0.3, width:0.6, height:0.3,  friction:0.0, allowSleep:false});
	lookupQuickObject[boxes[i].shape] = boxes[i];
}

var m3:QuickObject = sim.addBox({x:3, y:12.25 , width:1, height:0.25, allowSleep:false,fixedRotation:true, groupIndex:-1});

var j4:QuickObject = sim.addJoint({type:"revolute", a:m1.body, b:m3.body});
var j5:QuickObject = sim.addJoint({type:"revolute", a:m2.body, b:m3.body});

var t:Number = Math.PI;
var dropBox:int = 0;
var prevBox:QuickObject;
var resetVec:b2Vec2 = new b2Vec2(0,0);

function setGroupIndex(b:QuickObject, index:int):void{
	filter = b.shape.GetFilterData();
	filter.groupIndex = index;
	b.shape.SetFilterData(filter);
}

sim.start();
sim.addEventListener(QuickBox2D.STEP, onStep);
function onStep(evt:Event):void{
	dropBox++;
	
	if (dropBox % 80 == 0){
		index--;
		if (index > -1){
			if (prevBox){
				setGroupIndex(prevBox, 1);
			}
			prevBox = boxes[index]
			setGroupIndex(boxes[index], -1);
			m3.y += 0.05;
		}
	}
	
	if (index < 0){
		if (pusher.x > 3.5){
			pusher.x -= 0.05;
		}
	}
	for (var i:int = 0; i<boxNum; i++){
		if (boxes[i].y > 22){
			boxes[i].angle = 0;
			boxes[i].y = -2;
			boxes[i].x = 1;
			boxes[i].body.SetLinearVelocity(resetVec);
		}
	}
	
	if (index > 0){
	  anchor.x = 6 + 3 * Math.cos(t);
	  t += 0.01;
	}
}