cocos2d-x3.0 Physics新的物理引擎

1、说明：

3.0以后将box2d和chipmunk这两个物理引擎进行了封装，使用起来很的便利

2、详细用法：

1、创建物理世界场景

auto scene = Scene::createWithPhysics();
scene->getPhysicsWorld()->setDebugDrawMask(PhysicsWorld::DEBUGDRAW_ALL); //调试时使用

2、在场景中加入重力

Vect gravity = Vect(0.0f, -10.0f);  //-10表示重力向下
scene->getPhysicsWorld()->setGravity(gravity); 

3、创建物理边界，边界有碰撞体

auto body = PhysicsBody::createEdgeSegment(Point(0,0),Point(600,0),PHYSICSBODY_MATERIAL_DEFAULT, 3); //3是边线度
auto edgeNode = Node::create();
edgeNode->setPosition(Point(0,10));
edgeNode->setPhysicsBody(body);
scene->addChild(edgeNode);

4、创建精灵，给精灵绑定刚体，这个封装一个加入刚体的方法，怎样创建精灵这里不做过多的说明

void GameScene::addBoxBodyForSprite(Sprite *sprite){
auto body = PhysicsBody::createCircle(sprite->getContentSize().width / 2);
// body->setCategoryBitmask(0);   //当为0不仅能闯过并且还检測不到碰撞
body->setContactTestBitmask(1); //有碰撞检測
body_player->setRotationEnable(false); //设置是否旋转
/** 设置body是否受引力影响 */
body->setGravityEnable(true);  //是否受重力影响
sprite->setPhysicsBody(body);

5、碰撞监听 在onEnter中绑定监听

void GameScene::onEnter()
{
    Layer::onEnter();
    auto contactListener = EventListenerPhysicsContact::create();
    contactListener->onContactBegin = CC_CALLBACK_1(GameScene::onContactBegin, this);  //刚開始碰撞，监听
    contactListener->onContactPreSolve = CC_CALLBACK_2(GameScene::onContactPreSolve, this); //碰撞中监听
    auto dispatcher = Director::getInstance()->getEventDispatcher();
    dispatcher->addEventListenerWithSceneGraphPriority(contactListener, this);
}

6、開始碰撞监听函数

bool GameScene::onContactBegin( const PhysicsContact& contact){
    auto spriteA = (Sprite*)contact.getShapeA()->getBody()->getNode();
    auto spriteB = (Sprite*)contact.getShapeB()->getBody()->getNode();
    return true;  //返回true，才干够继续监听其他碰撞
}

7、碰撞中的监听(反弹力、摩擦力等属性可在此改动)

bool GameScene::onContactPreSolve(PhysicsContact& contact, PhysicsContactPreSolve& solve){
//	solve.setFriction(0);  //摩擦力
	solve.setRestitution(0);  //反弹力
//	solve.setSurfaceVelocity(Point(200,200));  //反弹运动方向
	return true;
}

8、physicsShape

//能够依据刚体得到PhysicsShape，然后改动PhysicsShape属性，包含，密度反弹力等。跟在碰撞检測中改动效果一样
//Vector<PhysicsShape*> physicShape = player->getPhysicsBody()->getShapes();
Vector<PhysicsShape*> physicShape = body_player->getShapes();
for(int i=0; i<physicShape.size();i++){
    physicShape.at(i)->setDensity(0); //密度
    physicShape.at(i)->setRestitution(0);  //反弹力
}

3、射线使用

1、实现

Point point1(10,10);
Point point2(1000,1000);
Point point3 = point2;

auto func = CC_CALLBACK_3(GameScene::anyRay, this);
scene->getPhysicsWorld()->rayCast(func, point1, point2, &point3);  //起始点、终点、保存碰撞的坐标位置 scene为開始创建的物理世界scene
//以下是画红色线方便调试查看
DrawNode *_node = DrawNode::create();
this->addChild(_node);
_node->drawSegment(point1, point2, 1, Color4F(1.0f, 0.0f, 0.0f, 1.0f));

2、射线碰撞监听

bool GameScene::anyRay(PhysicsWorld& world, const PhysicsRayCastInfo& info, void* data)
{
    *((Point*)data) = info.contact;
    return false;
}

4、參考文献

http://blog.csdn.net/v_leg/article/details/22584743

http://blog.csdn.net/st75033562/article/details/29574939

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