iphone - 检测两个物体的碰撞，每个物体都有不同的形状

Question

我想检测两个物体之间的碰撞，一个物体具有圆形形状，另一个物体具有凸形物体(通过使用顶点和顶点数量)，并且我使用接触监听器类来检测物体之间的碰撞。我尝试检测两个圆形之间的碰撞并且成功了，但是当我尝试检测两个物体(一个具有凸形状，另一个具有圆形形状)之间的碰撞时，它失败的!即使我使用标签来识别这些尸体。

如何检测具有两种不同形状(圆形和凸形)的两个物体？

ContactListener.h代码:

#import "Box2D.h"

class ContactListener : public b2ContactListener 
{
private: 
    void BeginContact(b2Contact* contact);
    void EndContact(b2Contact* contact);
};

ContactListener.mm代码:

#import "ContactListener.h"
#import "SimpleAudioEngine.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();

    if (spriteA != NULL && spriteB != NULL) {
        if (spriteA.tag == 1 && spriteB.tag == 50) { // this is work (two shapes are circles

            [[SimpleAudioEngine sharedEngine] playEffect:@"Pin.wav"];
            NSLog(@"Contact With Pin is Beginning");
        }

        if (spriteA.tag == 1 && spriteB.tag == 51) { // this is not work (one is circle shape and another one is convex shape)

            [[SimpleAudioEngine sharedEngine] playEffect:@"Jump.wav"];
            NSLog(@"Contact With Barrier is Beginning");
        }
    }
}

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();

    if (spriteA != NULL && spriteB != NULL) {

    }
}

上面代码的标签:

• 球(游戏主要 Sprite )形状的标签为 1
• 圆形标签为50
• 凸形标签为51

编辑:

这是对象主体创建的代码:

#define pinSpriteTag 50
#define barrierSpriteTag 51
#define ballSpriteTag 1

// Creating ball of game (has b2CircleShape)
-(void) createBallOfGameWithPositionX:(int)x yPosition:(int)y radius:(float)radius {

        // Put ball on screen
        ballOfGameSprite = [CCSprite spriteWithFile:@"GameBall-1-ipad.png"];
        ballOfGameSprite.position = ccp(x, y);
        [self addChild:ballOfGameSprite z:1 tag: ballSpriteTag];

        // Create body of ball
        b2BodyDef ballOfGameBodyDef;
        ballOfGameBodyDef.type = b2_staticBody;
        ballOfGameBodyDef.position.Set(ballOfGameSprite.position.x/PTM_RATIO, ballOfGameSprite.position.y/PTM_RATIO);
        ballOfGameBodyDef.userData = ballOfGameSprite;
        ballOfGameBody = world->CreateBody(&ballOfGameBodyDef);

        // Create Physics properties of ball
        b2CircleShape ballOfGameShape;
        ballOfGameShape.m_radius = radius/PTM_RATIO;

        // Create fixture of ball
        b2FixtureDef ballOfGameFixtureDef;
        ballOfGameFixtureDef.shape = &ballOfGameShape;
        ballOfGameFixtureDef.density = 0.9f;
        ballOfGameFixtureDef.friction = 1.0f;
        ballOfGameFixtureDef.restitution = 0.9f;
        ballOfGameBody->CreateFixture(&ballOfGameFixtureDef);

}

// Creating pin of game (has b2CircleShape)
-(void) createNormalPinOnScreenWithPositionX:(int)x yPosition:(int)y radius:(float)radius {

        // Put ball on screen
        CCSprite *pin = [CCSprite spriteWithFile:@"GamePinNormal-ipad.png"];
        pin.position = ccp(x, y);
        [self addChild:pin z:2 tag:pinSpriteTag];

        // Create body of ball
        b2BodyDef pinBodyDef;
        pinBodyDef.type = b2_staticBody;
        pinBodyDef.position.Set(pin.position.x/PTM_RATIO, pin.position.y/PTM_RATIO);
        pinBodyDef.userData = pin;
        b2Body *pinBody = world->CreateBody(&pinBodyDef);

        // Create Physics properties of ball
        b2CircleShape pinShape;
        pinShape.m_radius = radius/PTM_RATIO;

        // Create fixture of ball
        b2FixtureDef pinFixtureDef;
        pinFixtureDef.shape = &pinShape;
        pinFixtureDef.density = 0.9f;
        pinFixtureDef.friction = 1.0f;
        pinFixtureDef.restitution = 0.85f;
        pinBody->CreateFixture(&pinFixtureDef);
}

// Creating Barrier of game (has b2PolygonShape)
-(void) createBarrierOnScreenPositionX:(int)x yPosition:(int)y imageName:(NSString *)imageName verts:(b2Vec2*)verts verNum:(int)verNum {

    CCSprite *BarrierOfGameSprite = [CCSprite spriteWithFile:imageName];
    BarrierOfGameSprite.position = ccp(x, y);
    [self addChild:BarrierOfGameSprite z:1 tag:barrierSpriteTag];

    b2BodyDef BarrierOfGameBodyDef;
    BarrierOfGameBodyDef.type = b2_staticBody;
    BarrierOfGameBodyDef.position.Set(BarrierOfGameSprite.position.x/PTM_RATIO, BarrierOfGameSprite.position.y/PTM_RATIO);
    BarrierOfGameBodyDef.userData = BarrierOfGameSprite;

    b2Body *BarrierOfGameBody = world->CreateBody(&BarrierOfGameBodyDef);

    b2PolygonShape BarrierOfGameShape;
    BarrierOfGameShape.Set(verts, verNum);

    b2FixtureDef BarrierOfGameFixtureDef;
    BarrierOfGameFixtureDef.shape = &BarrierOfGameShape;    
    BarrierOfGameFixtureDef.density = 0.9f;
    BarrierOfGameFixtureDef.friction = 1.0f;
    BarrierOfGameFixtureDef.restitution = 0.0f;
    BarrierOfGameBody->CreateFixture(&BarrierOfGameFixtureDef); 

}

Answer 1

不检测两个形状之间的碰撞。最好的方法是将对象设置为body的userData。

@implemention RigidBody
-(id)init{
    ...
    self.body->userData = self;
}

然后比较类和地址

void beginContact(b2contact contact){
    RigidBody *A = (RigidBody*)contact->GetFixtureA()->GetBody()->GetUserData();
    if([A isKindOfClass:[RigidBody class]]){

    }
    //  Or
    if(self == A){

    }

希望对您有帮助。