package{
import Box2D.Collision.Shapes.b2CircleShape;
import Box2D.Collision.Shapes.b2PolygonShape;
import Box2D.Common.Math.b2Vec2;
import Box2D.Dynamics.b2Body;
import Box2D.Dynamics.b2BodyDef;
import Box2D.Dynamics.b2DebugDraw;
import Box2D.Dynamics.b2FixtureDef;
import Box2D.Dynamics.b2World;
import flash.display.Sprite;
import flash.events.Event;
[SWF(width=”800″,height=”600″,frameRate=”32″,backgroundColor=”0x000000″)]
public class MultiGravity extends Sprite{
private var world:b2World;
private var body:b2Body;
private var timeStep:Number;
private var iterations:uint;
private var pixelsPerMeter:Number = 30;
public function MultiGravity(){
createWorld();
makeDebugDraw();
createWall();
createBodies();
addEventListener(Event.ENTER_FRAME,onEnterframe);
}
private function createWorld():void{
var gravity:b2Vec2 = new b2Vec2(0.0,9.8);
var doSleep:Boolean = true;
world = new b2World(gravity,doSleep);
world.SetWarmStarting(true);
timeStep = 1.0/30.0;
iterations = 10;
}
private function createWall():void{
var bodyDef:b2BodyDef = new b2BodyDef();
bodyDef.position.Set(400/pixelsPerMeter,15/pixelsPerMeter);
body = world.CreateBody(bodyDef);
var shape:b2PolygonShape = new b2PolygonShape();
shape.SetAsBox(400/pixelsPerMeter,15/pixelsPerMeter);
body.CreateFixture2(shape);
bodyDef.position.Set(400/pixelsPerMeter,585/pixelsPerMeter);
body = world.CreateBody(bodyDef);
body.CreateFixture2(shape);
}
private function createBodies():void{
for(var i:int=0;i<10;i++){
var bodyDef:b2BodyDef = new b2BodyDef();
bodyDef.type = b2Body.b2_dynamicBody;
bodyDef.position.x = (Math.random()*600+120)/pixelsPerMeter;
bodyDef.position.y = (Math.random()*150)/pixelsPerMeter;
var hx:Number = (Math.random()*30+15)/pixelsPerMeter;
var hy:Number = (Math.random()*30+15)/pixelsPerMeter;
var fixtureDef:b2FixtureDef = new b2FixtureDef();
fixtureDef.density = 1.0;
fixtureDef.friction = 0.5;
fixtureDef.restitution = 0.2;
if(Math.random()<0.5){
bodyDef.userData = new Sprite();
bodyDef.userData.name ="square";
var square:b2PolygonShape = new b2PolygonShape();
square.SetAsBox(hx,hy);
fixtureDef.shape = square;
body = world.CreateBody(bodyDef);
body.CreateFixture(fixtureDef);
}
else{
bodyDef.userData = new Sprite();
bodyDef.userData.name = "circle";
var circle:b2CircleShape = new b2CircleShape();
circle.SetRadius(hx);
fixtureDef.shape = circle;
body = world.CreateBody(bodyDef);
body.CreateFixture(fixtureDef);
}
}
}
private function makeDebugDraw():void{
var debugDraw:b2DebugDraw = new b2DebugDraw();
var debugSprite:Sprite = new Sprite();
addChild(debugSprite);
debugDraw.SetSprite(debugSprite);
debugDraw.SetDrawScale(30.0);
debugDraw.SetFillAlpha(0.5);
debugDraw.SetLineThickness(1.0);
debugDraw.SetFlags(b2DebugDraw.e_shapeBit);
world.SetDebugDraw(debugDraw);
}
private function onEnterframe(e:Event):void{
world.Step(timeStep,iterations,iterations);
world.ClearForces();
world.DrawDebugData();
var reverseGravity:b2Vec2;
for(var body:b2Body = world.GetBodyList();body;body = body.GetNext()){
if(body.GetUserData() != null){
if(body.GetUserData().name == "circle"){
reverseGravity = new b2Vec2(0.0,-20*body.GetMass());
//reverseGravity = new b2Vec2(0.0,-9.8*body.GetMass());
body.ApplyForce(reverseGravity,body.GetWorldCenter());
}
}
}
}
}
}
[/code]
转载请注明：陈童的博客 » box2d施加多个重力
