Question

我做了一个简单的游戏。

它有许多钻石图像和一个球。当球与钻石形状接触时，则发生碰撞。在我的应用中，当球在边缘上碰触然后碰撞正常工作但是当球碰到角落时碰撞不起作用。

听到代码..

- (id)init {

if ((self=[super init])) {

    CGSize winSize = [CCDirector sharedDirector].winSize;

    self.isTouchEnabled = YES;

    self.isAccelerometerEnabled=YES;
    // Create a world
    b2Vec2 gravity = b2Vec2(0.0f, 0.0f);
    bool doSleep = true;
    _world = new b2World(gravity, doSleep);

    // Create edges around the entire screen
    b2BodyDef groundBodyDef;
    groundBodyDef.position.Set(0,0);
    _groundBody = _world->CreateBody(&groundBodyDef);
    b2PolygonShape groundBox;
    b2FixtureDef groundBoxDef;
    groundBoxDef.shape = &groundBox;
    groundBox.SetAsEdge(b2Vec2(0,0), b2Vec2(winSize.width/PTM_RATIO, 0));
    _bottomFixture = _groundBody->CreateFixture(&groundBoxDef);
    groundBox.SetAsEdge(b2Vec2(0,0), b2Vec2(0, winSize.height/PTM_RATIO));
    _groundBody->CreateFixture(&groundBoxDef);
    groundBox.SetAsEdge(b2Vec2(0, winSize.height/PTM_RATIO), b2Vec2(winSize.width/PTM_RATIO, winSize.height/PTM_RATIO));
    _groundBody->CreateFixture(&groundBoxDef);
    groundBox.SetAsEdge(b2Vec2(winSize.width/PTM_RATIO, winSize.height/PTM_RATIO), b2Vec2(winSize.width/PTM_RATIO, 0));
    _groundBody->CreateFixture(&groundBoxDef);

    // Create sprite and add it to the layer
    CCSprite *ball = [CCSprite spriteWithFile:@"ball1.png" rect:CGRectMake(0, 0, 16,16)];
   // ball.position = ccp(180, 400);
    ball.tag = 1;

// Create ball body 
    b2BodyDef ballBodyDef;
    ballBodyDef.type = b2_dynamicBody;
    ballBodyDef.position.Set(180/PTM_RATIO, 450/PTM_RATIO);
    ballBodyDef.userData = ball;
     ballBody = _world->CreateBody(&ballBodyDef);

    // Create circle shape
    b2CircleShape circle;
    circle.m_radius = 16/PTM_RATIO;
    //circle.m_radius = 50/PTM_RATIO;

    // Create shape definition and add to body
    b2FixtureDef ballShapeDef;
    ballShapeDef.shape = &circle;
    ballShapeDef.density = 1.0f;
    ballShapeDef.friction = 0.0f; // We don't want the ball to have friction!
    ballShapeDef.restitution = 0.0f;
    _ballFixture = ballBody->CreateFixture(&ballShapeDef);

    // Give shape initial impulse...
    b2Vec2 force = b2Vec2(0, 0);
    ballBody->ApplyLinearImpulse(force, ballBodyDef.position);

    for(int i = 0; i < 5; i++) 


    {
        static int padding=25;



        CCSprite *block = [CCSprite spriteWithFile:@"diamond2.png"];
       int  xOffset = padding+block.contentSize.width/5+((block.contentSize.width+padding)*i);
        block.position = ccp(xOffset, 250);
        block.tag = 2;
        [self addChild:block];


        // Create block body
        b2BodyDef blockBodyDef;
       // blockBodyDef.type = b2_dynamicBody;
        blockBodyDef.position.Set(xOffset/PTM_RATIO, 400/PTM_RATIO);
        blockBodyDef.userData = block;

        b2Body *blockBody = _world->CreateBody(&blockBodyDef);

        // Create block shape
        b2PolygonShape blockShape;
        blockShape.SetAsBox(block.contentSize.width/PTM_RATIO/8,
                            block.contentSize.height/PTM_RATIO/8
                            );

        // Create shape definition and add to body
        b2FixtureDef blockshapeDef;
        blockshapeDef.shape = &blockShape;
        blockshapeDef.density = 0.0;
        blockshapeDef.friction = 10.0;
        blockshapeDef.restitution = 0.1f;
        blockBody->CreateFixture(&blockshapeDef);
    }

    [self addChild:ball]; 

// Create contact listener
    _contactListener = new MyContactListener();
    _world->SetContactListener(_contactListener);

    [[SimpleAudioEngine sharedEngine] playBackgroundMusic:@"background-music-aac.caf"];

    [self schedule:@selector(tick:)];

}
return self;

}

- (void)tick:(ccTime) dt {

   // bool blockFound = false;
_world->Step(dt, 10, 10);    
for(b2Body *b = _world->GetBodyList(); b; b=b->GetNext()) {    
    if (b->GetUserData() != NULL) {
        CCSprite *sprite = (CCSprite *)b->GetUserData();     



        if (sprite.tag == 1) {
            static int maxSpeed = 20;

            b2Vec2 velocity = b->GetLinearVelocity();
            float32 speed = velocity.Length();

            // When the ball is greater than max speed, slow it down by
            // applying linear damping.  This is better for the simulation
            // than raw adjustment of the velocity.
            if (speed > maxSpeed) {
                b->SetLinearDamping(0.2);
            } else if (speed < maxSpeed) {
                b->SetLinearDamping(0.0);
            }

        }

       sprite.position = ccp(b->GetPosition().x * PTM_RATIO,
                                b->GetPosition().y * PTM_RATIO);
        sprite.rotation = 1 * CC_RADIANS_TO_DEGREES(b->GetAngle());

}
}
}

Plz帮助我检测钻石形状角落附近正确的collsion检测....

Answer 1

我不确定我是否理解，但似乎你没有制作钻石，你正在制作方形/盒子：

blockShape.SetAsBox(block.contentSize.width/PTM_RATIO/8,block.contentSize.height/PTM_RATIO/8);

也许这就是为什么你说碰撞不起作用的原因。

如果你的身体是正方形而你的精灵是钻石，则有三种选择：

或者钻石具有相同的宽度和高度，旋转正方形只需要。碰撞应该没问题。

或其他形状碰撞在正方形的（看不见的）角落时不应该在那里（当精灵/菱形适合正方形，正方形没有旋转或钻石有宽度！=高度需要定制的形状）

或者其他形状不与钻石精灵角碰撞（当正方形较小并且适合钻石精灵时）。

还有其他方法可以创建自定义形状，如：

void b2PolygonShape::Set(const b2Vec2* vertices, int32 count) void b2PolygonShape::SetAsEdge(const b2Vec2& v1, const b2Vec2& v2)

在box2d中检测钻石形状的问题

1 个答案: