Spritekit SKPhysicsBody销接头

Question

我在尝试制造一个摩天轮。它由三种不同的精灵组成:底座(腿)、身体(旋转的圆形部分)和座椅(总共16个)。

在下面的代码中，我将底座添加到场景中，然后将身体附加到底座上，最后将每个座椅附加到身体上。座椅目前(以一种奇怪的方式)与身体旋转。我根本不想让座位旋转。我做错了什么？

注:更新后有@dragoneye的评论和建议

-(void) initFerrisWheel {
    self.physicsWorld.gravity = CGVectorMake(0, 0);

    //creates the body of the ferris wheel and attaches it to the base
    SKSpriteNode *ferrisWheel = (SKSpriteNode*)[self childNodeWithName:@"ferriswheel_base"];
    SKTexture *bodyTexture = [[SharedAssetsManager sharedData].menuAssets objectForKey:@"ferriswheel_body"];
    SKSpriteNode *body = [[SKSpriteNode alloc] initWithTexture:bodyTexture];
    [body setZPosition:2];
    [body setPosition:CGPointMake(0, 55)];
    body.physicsBody = [SKPhysicsBody bodyWithCircleOfRadius:self.size.height/2];
    [ferrisWheel addChild:body];

    //rotates the body of the ferris wheel
    SKAction *rotateSequence = [SKAction rotateByAngle:-0.785 duration:2.0];
    SKAction *rotateFinal = [SKAction repeatActionForever:rotateSequence];
    [body runAction:rotateFinal];

    SKTexture *seatTexture = [[SharedAssetsManager sharedData].menuAssets objectForKey:@"ferriswheel_seat"];

    int r = 130; //radius of the body for the ferris wheel
    for (int i = 0; i < 16; i++) {
        //creates a seat and places it on the body
        SKSpriteNode *seat = [[SKSpriteNode alloc] initWithTexture:seatTexture];
        float x = r * cosf(2*M_PI*i/16);
        float y = r * sinf(2*M_PI*i/16);
        [seat setPosition:CGPointMake(x, y)];
        [seat setZPosition:3];
        [body addChild:seat];

        //physics body stuff
        seat.physicsBody = [SKPhysicsBody bodyWithCircleOfRadius:seat.size.height/2];
        seat.physicsBody.dynamic = YES;

        CGPoint anchor = CGPointMake(x, y);
        SKPhysicsJointPin *pin = [SKPhysicsJointPin jointWithBodyA:body.physicsBody bodyB:seat.physicsBody anchor:anchor];
        [self.physicsWorld addJoint:pin];
        pin.shouldEnableLimits = YES;
        pin.lowerAngleLimit = -0.25;
        pin.upperAngleLimit = 0.25;

    }
}

Answer 1

经过一段时间的努力，并创建了一个简单的测试项目，我意识到我的问题是，我把摩天轮的车身作为一个子节点附加到底座上，我还把座椅作为子节点附加到身体上。虽然可能有办法让这个工作，我把所有的坐标都基于世界坐标。这可能会对未来的人有所帮助。这是固定代码：

-(void) initFerrisWheel {
    //creates the body of the ferris wheel and attaches it to the base
    SKSpriteNode *ferrisWheel = (SKSpriteNode*)[self childNodeWithName:@"ferriswheel_base"];
    SKTexture *bodyTexture = [[SharedAssetsManager sharedData].menuAssets objectForKey:@"ferriswheel_body"];
    SKSpriteNode *body = [[SKSpriteNode alloc] initWithTexture:bodyTexture];
    [body setZPosition:2];
    [body setPosition:CGPointMake(ferrisWheel.position.x, ferrisWheel.position.y + 55)];
    body.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:body.size];
    body.physicsBody.affectedByGravity = NO;
    [self addChild:body];

    //rotates the body of the ferris wheel
    SKAction *rotateSequence = [SKAction rotateByAngle:-0.785 duration:2.0];
    SKAction *rotateFinal = [SKAction repeatActionForever:rotateSequence];
    [body runAction:rotateFinal];

    SKTexture *seatTexture = [[SharedAssetsManager sharedData].menuAssets objectForKey:@"ferriswheel_seat"];

    int r = 130; //radius of the body for the ferris wheel
    for (int i = 0; i < 16; i++) {
        //creates a seat and places it on the body
        SKSpriteNode *seat = [[SKSpriteNode alloc] initWithTexture:seatTexture];
        float x = body.position.x + r * cosf(2*M_PI*i/16);
        float y = body.position.y + r * sinf(2*M_PI*i/16);
        [seat setPosition:CGPointMake(x, y)];
        [seat setZPosition:3];
        [self addChild:seat];

        //physics body stuff
        seat.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:seat.size];
        seat.physicsBody.affectedByGravity = NO;

        SKPhysicsJointPin *pin = [SKPhysicsJointPin jointWithBodyA:body.physicsBody bodyB:seat.physicsBody anchor:seat.position];
        [self.physicsWorld addJoint:pin];
    }
}

Answer 2

设置连接的上、下限值。

pinJoint.shouldEnableLimits=TRUE；

pinJoint.lowerAngleLimit = -0.25；

pinJoint.upperAngleLimit = 0.25；