PhysicsBody物理世界

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介绍

在3.2的重力系统，创建场景就不能用Scence *s = Scence::create(); 要用：Scence *s = Scence::createWithPhysics();

bool T07PhysicsWorld::init(){Layer::init();PhysicsBody* bodyA;PhysicsBody* bodyB;{//createCircle 创建一个圆形的bodyPhysicsBody* body = PhysicsBody::createCircle(20, PhysicsMaterial(1.0f, 1.0f, 0.0f));//PhysicsMaterial（密度，弹力，摩擦力）bodyA = body;Sprite* sprite = Sprite::create();#if 0/*此处精灵看不见，因为没有具体的精灵，在3.2里我们可以把这个body的边框画出来，在场景那边设置下：Scene* s = Scene::createWithPhysics();//就是下面这两句PhysicsWorld* world = s->getPhysicsWorld();//取出世界world->setDebugDrawMask(PhysicsWorld::DEBUGDRAW_ALL);*/#endifsprite->setPhysicsBody(body);addChild(sprite);sprite->setPosition(winSize.width / 2, winSize.height / 2);//设置速度，在x， y方向的速度。body->setVelocity(Vect(100, 200));}{//加四边形边框PhysicsBody* body = PhysicsBody::createEdgeBox(winSize, PhysicsMaterial(1.0f, 1.0f, 0.0f));bodyB = body;Sprite* sprite = Sprite::create();addChild(sprite);sprite->setPhysicsBody(body);sprite->setPosition(winSize.width / 2, winSize.height / 2);}//碰撞检测{//body碰撞要设置BitMask，表示这个body要不要计算碰撞bodyA->setContactTestBitmask(0x1);bodyB->setContactTestBitmask(0x1);//设置是哪个组的。组与组之间碰撞检测，组内部不做碰撞检测。bodyA->setGroup(1);bodyB->setGroup(2);//碰撞检测auto ev = EventListenerPhysicsContactWithBodies::create(bodyA, bodyB);//当碰撞开始时调用此函数ev->onContactBegin = [](PhysicsContact& contact){CCLog("Began Contact...........");return true;};_eventDispatcher->addEventListenerWithSceneGraphPriority(ev, this);}//也可以通过形状做碰撞检测{//一个body对应多个Shapesauto ev = EventListenerPhysicsContactWithShapes::create(bodyA->getShapes().at(0),bodyB->getShapes().at(0));ev->onContactBegin = [](PhysicsContact& contact){CCLog("Shape Began Contact...........");return true;};_eventDispatcher->addEventListenerWithSceneGraphPriority(ev, this);}{auto ev = EventListenerPhysicsContactWithGroup::create(3); //3是Gid等于3的有碰撞，就调用。类推。ev->onContactBegin = [](PhysicsContact& contact){CCLog("Group Began Contact...........");return true;};_eventDispatcher->addEventListenerWithSceneGraphPriority(ev, this);}return true;}

一个body可以对应多个shape，比如复杂的形状可以拆分为几个shape，如乌龟可以将头和脚等分开。

{PhysicsBody* body = PhysicsBody::create();PhysicsShape* shape1 = PhysicsShapeBox::create(Size(40, 40), PHYSICSBODY_MATERIAL_DEFAULT, Vec2::ZERO);body->addShape(shape1);PhysicsShape* shape2 = PhysicsShapeCircle::create(10, PHYSICSBODY_MATERIAL_DEFAULT, Vec2(-30, 0));body->addShape(shape2);//Sprite* sprite = Sprite::create();Node* node = Node::create();node->setPhysicsBody(body);addChild(node);node->setPosition(winSize.width / 2, winSize.height / 2);}// 边框{PhysicsBody* body = PhysicsBody::createEdgeBox(winSize, PhysicsMaterial(1.0f, 1.0f, 0.0f));Sprite* sprite = Sprite::create();addChild(sprite);sprite->setPhysicsBody(body);sprite->setPosition(winSize.width / 2, winSize.height / 2);}

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