{"id":783,"date":"2009-01-15T09:00:32","date_gmt":"2009-01-15T08:00:32","guid":{"rendered":"http:\/\/www.matthijskamstra.nl\/blog\/?p=783"},"modified":"2009-02-14T14:53:14","modified_gmt":"2009-02-14T13:53:14","slug":"hello-box2d-part-4","status":"publish","type":"post","link":"https:\/\/www.matthijskamstra.nl\/blog\/2009\/01\/15\/hello-box2d-part-4\/","title":{"rendered":"Hello box2D – part 4"},"content":{"rendered":"

In my previous post<\/a> I update the “Hello world” for box2D so that you can see something visual interesting.
\nYou can find the original here: AS3: Hello Box2D<\/a>.<\/p>\n

Today I will post the same code but now how it should be.
\nKeeping the coding conventions<\/a> in mind and making it easier to reuse code.<\/p>\n

Still keeping in mind the original Hello world<\/a><\/p>\n

[as]
\npackage {<\/p>\n

\timport flash.display.*;
\n\timport flash.events.*;
\n\t\/\/ Box2D Classes used in this “Hello world”
\n\timport Box2D.Dynamics.*;
\n\timport Box2D.Collision.*;
\n\timport Box2D.Collision.Shapes.*;
\n\timport Box2D.Common.Math.*;<\/p>\n

\t\/\/[SWF(width=”640″, height=”480″, backgroundColor=”#000000″, frameRate=”60″)]
\n\tpublic class HelloWorld extends MovieClip {<\/p>\n

\t\tpublic var world:b2World;
\n\t\tpublic var iterations:int \t\t= 10;
\n\t\tpublic var timeStep:Number \t\t= 1.0 \/ 60.0;
\n\t\tpublic var worldScale:Number \t= 30.0;<\/p>\n

\t\t\/\/ to see what you have created
\n\t\tprivate var debugDraw:b2DebugDraw;
\n\t\tprivate var isDebugDrawing:Boolean = true;\t\/\/ change to false and there is no debugDraw<\/p>\n

\t\t\/\/ constructor
\n\t\tpublic function HelloWorld() {
\n\t\t\t\/\/trace( “HelloWorld.HelloWorld” );
\n\t\t\tinit();
\n\t\t}<\/p>\n

\t\t\/**
\n\t\t * lets start building our “Hello world” box2D program
\n\t\t *\/
\n\t\tprivate function init():void {
\n\t\t\ttrace( “HelloWorld.init” );<\/p>\n

\t\t\tcreateWorld();
\n\t\t\tcreatingGroundBox();
\n\t\t\tcreatingDynamicBody();<\/p>\n

\t\t\tsetupDebugDraw();<\/p>\n

\t\t\t\/\/ Add event for main loop
\n\t\t\taddEventListener(Event.ENTER_FRAME, onUpdateHandler, false, 0, true);
\n\t\t}<\/p>\n

\t\t\/**
\n\t\t * http:\/\/www.box2d.org\/wiki\/index.php?title=Manual\/AS3#Creating_a_World
\n\t\t *\/
\n\t\tprivate function createWorld():void {
\n\t\t\t\/\/ Creat world AABB
\n\t\t\tvar worldAABB:b2AABB = new b2AABB();
\n\t\t\tworldAABB.lowerBound.Set(-100.0, -100.0);
\n\t\t\tworldAABB.upperBound.Set(100.0, 100.0);<\/p>\n

\t\t\t\/\/ Define the gravity vector
\n\t\t\tvar gravity:b2Vec2 = new b2Vec2 (0.0, -10.0); <\/p>\n

\t\t\t\/\/ Allow bodies to sleep
\n\t\t\tvar doSleep:Boolean = true;<\/p>\n

\t\t\t\/\/ Construct a world object
\n\t\t\tworld = new b2World(worldAABB, gravity, doSleep);
\n\t\t}<\/p>\n

\t\t\/**
\n\t\t * http:\/\/www.box2d.org\/wiki\/index.php?title=Manual\/AS3#Creating_a_Ground_Box
\n\t\t *\/
\n\t\tprivate function creatingGroundBox():void {
\n\t\t\tvar groundBodyDef:b2BodyDef = new b2BodyDef();
\n\t\t\tgroundBodyDef.position.Set(0.0, -9.0);<\/p>\n

\t\t\tvar groundBody:b2Body = world.CreateBody(groundBodyDef);<\/p>\n

\t\t\tvar groundShapeDef:b2PolygonDef = new b2PolygonDef();
\n\t\t\tgroundShapeDef.SetAsBox(50.0, 10.0);<\/p>\n

\t\t\tgroundBody.CreateShape(groundShapeDef);
\n\t\t}<\/p>\n

\t\t\/**
\n\t\t * http:\/\/www.box2d.org\/wiki\/index.php?title=Manual\/AS3#Creating_a_Dynamic_Body
\n\t\t *\/
\n\t\tprivate function creatingDynamicBody ():void {
\n\t\t\tvar bodyDef:b2BodyDef = new b2BodyDef();
\n\t\t\tbodyDef.position.Set(10.0, 10.0);
\n\t\t\tvar body:b2Body = world.CreateBody(bodyDef);<\/p>\n

\t\t\tvar shapeDef:b2PolygonDef = new b2PolygonDef();
\n\t\t\tshapeDef.SetAsBox(1.0, 1.0);
\n\t\t\tshapeDef.density = 1.0;
\n\t\t\tshapeDef.friction = 0.3;
\n\t\t\tshapeDef.restitution = 0.8;
\n\t\t\tbody.CreateShape(shapeDef);
\n\t\t\tbody.SetMassFromShapes();<\/p>\n

\t\t}<\/p>\n

\t\t\/\/ extra to visualize
\n\t\tprivate function setupDebugDraw():void {
\n\t\t\tif(isDebugDrawing) {
\n\t\t\t\tdebugDraw = new b2DebugDraw();
\n\t\t\t\tdebugDraw.m_sprite = new Sprite();<\/p>\n

\t\t\t\taddChild(debugDraw.m_sprite);<\/p>\n

\t\t\t\tdebugDraw.m_drawScale = 30;
\n\t\t\t\tdebugDraw.m_fillAlpha = .25;
\n\t\t\t\tdebugDraw.m_lineThickness = 1;
\n\t\t\t\tdebugDraw.m_drawFlags = b2DebugDraw.e_shapeBit | b2DebugDraw.e_jointBit ;
\n\t\t\t\tworld.SetDebugDraw (debugDraw);
\n\t\t\t}
\n\t\t}<\/p>\n

\t\t\/**
\n\t\t * http:\/\/www.box2d.org\/wiki\/index.php?title=Manual\/AS3#Simulating_the_World_.28of_Box2D.29
\n\t\t *\/
\n\t\tpublic function onUpdateHandler(e:Event):void{
\n\t\t\tworld.Step(timeStep, iterations);
\n\t\t}<\/p>\n

\t} \/\/ end class<\/p>\n

} \/\/ end package
\n[\/as]<\/p>\n

So all you need to do is CTRL+ENTER.<\/p>\n

And you will have something like this:<\/p>\n

[swf]http:\/\/www.matthijskamstra.nl\/blog\/wp-content\/uploads\/helloworldbox2d_nice.swf,520, 390[\/swf]<\/div>\n","protected":false},"excerpt":{"rendered":"

In my previous post I update the “Hello world” for box2D so that you can see something visual interesting. You can find the original here: AS3: Hello Box2D. Today I will post the same code but now how it should be. Keeping the coding conventions in mind and making it easier to reuse code. Still […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[22,3],"tags":[408,230,231,398,159],"class_list":["post-783","post","type-post","status-publish","format-standard","hentry","category-as3","category-flash","tag-as3","tag-box2d","tag-box2dflash","tag-flash","tag-flashdevelop"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t