box2d旋转关节之绳索

Box2D everyinch 2625℃ 0评论

package{
import Box2D.Collision.Shapes.b2PolygonShape;
import Box2D.Collision.Shapes.b2Shape;
import Box2D.Collision.b2AABB;
import Box2D.Common.Math.b2Vec2;
import Box2D.Dynamics.Joints.b2MouseJoint;
import Box2D.Dynamics.Joints.b2MouseJointDef;
import Box2D.Dynamics.Joints.b2RevoluteJointDef;
import Box2D.Dynamics.b2Body;
import Box2D.Dynamics.b2BodyDef;
import Box2D.Dynamics.b2DebugDraw;
import Box2D.Dynamics.b2Fixture;
import Box2D.Dynamics.b2FixtureDef;
import Box2D.Dynamics.b2World;

import flash.display.Sprite;
import flash.events.Event;
import flash.events.MouseEvent;

[SWF(width=”800″,height=”600″,frameRate=”32″,backgroundColor=”0x000000″)]
public class RevoluteJoint_Rope extends Sprite{
private var world:b2World;
private var timeStep:Number;
private var iterations:uint;
private var pixelsPerMeter:Number = 30;
private var mouseJoint:b2MouseJoint;
private var mousePVec:b2Vec2 = new b2Vec2();

public function RevoluteJoint_Rope(){
createWorld();
makeDebugDraw();
createRope();
addEventListener(Event.ENTER_FRAME,onEnterframe);
stage.addEventListener(MouseEvent.MOUSE_DOWN,onMouseDown);
stage.addEventListener(MouseEvent.MOUSE_UP,onMouseUp);
}

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 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 createRope():void{
//天棚
var bodyDef:b2BodyDef = new b2BodyDef();
bodyDef.position.Set(400/pixelsPerMeter,0);
var body:b2Body = world.CreateBody(bodyDef);
var box:b2PolygonShape = new b2PolygonShape();
box.SetAsBox(60/pixelsPerMeter,15/pixelsPerMeter);
body.CreateFixture2(box);
var link:b2Body = body;
var fixtureDef:b2FixtureDef = new b2FixtureDef();
var jointDef:b2RevoluteJointDef = new b2RevoluteJointDef();
for(var i:int=0;i<10;i++){ // 10段绳索 bodyDef = new b2BodyDef(); bodyDef.type = b2Body.b2_dynamicBody; bodyDef.position.Set(400/pixelsPerMeter,(i*30+30)/pixelsPerMeter);trace(i*30+15); box = new b2PolygonShape(); box.SetAsBox(3/pixelsPerMeter,15/pixelsPerMeter); fixtureDef.shape = box; fixtureDef.density = 100; fixtureDef.friction = 0.5; fixtureDef.restitution = 0.2; body = world.CreateBody(bodyDef); body.CreateFixture(fixtureDef); // Joint jointDef.Initialize(link,body,new b2Vec2(400/pixelsPerMeter,(i*30+15)/pixelsPerMeter)); world.CreateJoint(jointDef); link = body; } // 绳索悬挂物 bodyDef = new b2BodyDef(); bodyDef.type = b2Body.b2_dynamicBody; bodyDef.position.Set(400/pixelsPerMeter,330/pixelsPerMeter); box = new b2PolygonShape(); box.SetAsBox(15/pixelsPerMeter,15/pixelsPerMeter); fixtureDef = new b2FixtureDef(); fixtureDef.shape = box; fixtureDef.density = 2; fixtureDef.friction = 0.5; fixtureDef.restitution = 0.2; body = world.CreateBody(bodyDef); body.CreateFixture(fixtureDef); jointDef.Initialize(link,body,new b2Vec2(400/pixelsPerMeter,315/pixelsPerMeter)); world.CreateJoint(jointDef); } private function onMouseDown(e:MouseEvent):void{ var body:b2Body = getBodyAtMouse(); if(body){ var mouseJointDef:b2MouseJointDef = new b2MouseJointDef(); mouseJointDef.bodyA = world.GetGroundBody(); mouseJointDef.bodyB = body; mouseJointDef.target.Set(mouseX/pixelsPerMeter,mouseY/pixelsPerMeter); mouseJointDef.maxForce = 30000; mouseJoint = world.CreateJoint(mouseJointDef) as b2MouseJoint; } } private function onMouseUp(e:MouseEvent):void{ if(mouseJoint){ world.DestroyJoint(mouseJoint); mouseJoint = null; } } private function getBodyAtMouse(includeStatic:Boolean = false):b2Body{ var mouseXWorldPhys:Number = mouseX/pixelsPerMeter; var mouseYWorldPhys:Number = mouseY/pixelsPerMeter; mousePVec.Set(mouseXWorldPhys,mouseYWorldPhys); var aabb:b2AABB = new b2AABB(); aabb.lowerBound.Set(mouseXWorldPhys-0.001,mouseYWorldPhys-0.001); aabb.upperBound.Set(mouseXWorldPhys+0.001,mouseYWorldPhys+0.001); var body:b2Body = null; var fixture:b2Fixture; function GetBodyCallBack(fixture:b2Fixture):Boolean{ var shape:b2Shape = fixture.GetShape(); if(fixture.GetBody().GetType() != b2Body.b2_staticBody || includeStatic){ var inside:Boolean = shape.TestPoint(fixture.GetBody().GetTransform(),mousePVec); if(inside){ body = fixture.GetBody(); return false; } } return true; } world.QueryAABB(GetBodyCallBack,aabb); return body; } private function onEnterframe(e:Event):void{ world.Step(timeStep,iterations,iterations); world.ClearForces(); world.DrawDebugData(); if(mouseJoint){ var xpos:Number = mouseX/pixelsPerMeter; var ypos:Number = mouseY/pixelsPerMeter; var v2:b2Vec2 = new b2Vec2(xpos,ypos); mouseJoint.SetTarget(v2); } } } } [/code]



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