Box2d物理引擎:b2ContactListener类碰撞检测

来源：互联网发布：遗传算法优缺编辑：程序博客网时间：2024/04/27 19:32

box2d有一个名为b2ContactListener类，需要继承此类，来接收碰撞的回调。
此类为c++代码。在xcode中，需要将.m文件更改为.mm文件

//接口文件
#import "Box2D.h"

class ContactListener : public b2ContactListener
{
private:
    //碰撞开始
    void BeginContact(b2Contact* contact);
    //碰撞结束
    void EndContact(b2Contact* contact);
};

//实现文件

#import "ContactListener.h"
#import "cocos2d.h"

void ContactListener::BeginContact(b2Contact* contact)
{
    b2Body* bodyA = contact->GetFixtureA()->GetBody();
    b2Body* bodyB = contact->GetFixtureB()->GetBody();
    CCSprite* spriteA = (CCSprite*)bodyA->GetUserData();
    CCSprite* spriteB = (CCSprite*)bodyB->GetUserData();

    //更改碰撞体颜色
    if (spriteA != NULL && spriteB != NULL)
    {
        spriteA.color = ccMAGENTA;
        spriteB.color = ccMAGENTA;
    }
}

void ContactListener::EndContact(b2Contact* contact)
{
    b2Body* bodyA = contact->GetFixtureA()->GetBody();
    b2Body* bodyB = contact->GetFixtureB()->GetBody();
    CCSprite* spriteA = (CCSprite*)bodyA->GetUserData();
    CCSprite* spriteB = (CCSprite*)bodyB->GetUserData();

    //更改碰撞体颜色
    if (spriteA != NULL && spriteB != NULL)
    {
        spriteA.color = ccWHITE;
        spriteB.color = ccWHITE;
    }
}

//在刚体世界中添加监听
-(id) init
{
    if ((self = [super init]))
    {
        //创建物理引擎世界
        b2Vec2 gravity = b2Vec2(0.0f, -10.0f);
        bool allowBodiesToSleep = true;
        world = new b2World(gravity, allowBodiesToSleep);

        //向刚体世界中添加监听
        contactListener = new ContactListener();
        world->SetContactListener(contactListener);
    ｝
｝

-(void) dealloc
{
    //删除监听
    delete contactListener;
    [super dealloc];
}