在cocos2dx v3版以后骄蝇，官方對Box2d和chipmunk兩個物理引擎進(jìn)行了封裝，對于我們開發(fā)人員而言，使用物理引擎的難度大大降低炊琉。
這里以構(gòu)建一個小車為例，對封裝的方法進(jìn)行介紹。

car.png

如圖所示苔咪，小車的組成很簡單锰悼，一個長方形加兩個圓形，貼圖都使用了同一個圖片团赏，只做演示使用箕般。

關(guān)鍵代碼：

//添加小車方法，參數(shù)為觸摸點(diǎn)坐標(biāo)
void Sence1::addNewCarAtPosition(Vec2 p) {
    //獲取屏幕大小
    Size visibleSize = Director::getInstance()->getVisibleSize();
    //獲取起點(diǎn)（在cocos2dx中舔清，以屏幕的左下角為坐標(biāo)原點(diǎn)）
    Vec2 origin = Director::getInstance()->getVisibleOrigin();

    //創(chuàng)建一個精靈對象丝里，作為長方形的車身
    auto boxC = Sprite::create("whiteSprite.png");
    //設(shè)置觸摸點(diǎn)為精靈所在的坐標(biāo)
    boxC->setPosition(origin + p);
    //創(chuàng)建物理Body
    //以精靈的寬的兩倍，精靈的高度為大小創(chuàng)建一個Box Body
    auto boxCBody = PhysicsBody::createBox(Size(boxC->getContentSize().width*2,boxC->getContentSize().height));
    //為精靈設(shè)置物理Body
    boxC->setPhysicsBody(boxCBody);
    //設(shè)置物理Body的類別掩碼
    boxCBody->setCategoryBitmask(0x01);
    //設(shè)置物理body的碰撞掩碼
    boxCBody->setCollisionBitmask(0x01);
    //設(shè)置物理Body不受重力影響
    boxCBody->setGravityEnable(false);
    //添加精靈到物理世界
    addChild(boxC, 30, 102);

    auto boxA = Sprite::create("whiteSprite.png");
    //將精靈的位置設(shè)置在觸摸點(diǎn)向左偏移boxC寬度的一半体谒，向下偏移boxC高度的一半
    boxA->setPosition(origin + p +Vec2(-boxC->getContentSize().width/2,-boxC->getContentSize().height/2));

    auto boxABody = PhysicsBody::createCircle(boxA->getContentSize().width/2);
//  boxABody->setAngularVelocity(2.0f);
    boxABody->setCategoryBitmask(0x10);
    boxABody->setCollisionBitmask(0x10);
    boxA->setPhysicsBody(boxABody);

    addChild(boxA, 10, 100);

    auto boxB = Sprite::create("whiteSprite.png");
    boxB->setPosition(origin + p + Vec2(boxC->getContentSize().width/2, -boxC->getContentSize().height/2));
    auto boxBBody = PhysicsBody::createCircle(boxB->getContentSize().width/2);
    boxBBody->setAngularVelocity(2.0f);
    boxBBody->setCategoryBitmask(0x10);
    boxBBody->setCollisionBitmask(0x10);
    boxB->setPhysicsBody(boxBBody);
    addChild(boxB, 20, 101);


    auto world = this->getScene()->getPhysicsWorld();
    //使用圖釘關(guān)節(jié)將boxABody與boxCBody連接起來杯聚，坐標(biāo)我認(rèn)為是相對錨點(diǎn)的偏移
    PhysicsJointPin* jointCA = PhysicsJointPin::construct(boxABody,
            boxCBody, Vec2(0, 0),Vec2(-boxC->getContentSize().width/2-10,-boxC->getContentSize().height/2));
    PhysicsJointPin* jointCB = PhysicsJointPin::construct(boxBBody,
                boxCBody, Vec2(0, 0),Vec2(boxC->getContentSize().width/2+10,-boxC->getContentSize().height/2));
//  PhysicsJointDistance* jointAB = PhysicsJointDistance::construct(boxABody,
//                  boxBBody, Vec2(0, 0), Vec2(0,0));
    world->addJoint(jointCA);
    world->addJoint(jointCB);
//  world->addJoint(jointAB);

}