创建凸 SKPhisycsBodies

Question

我在Apple提供的新框架中基本上尝试了一个带孔的矩形，唯一的问题是它的默认方法bodyWithPolygonFromPath不接受凹多边形，所以我尝试如下解决问题：

        CGPathMoveToPoint   (path, NULL, self.size.width/4.0,   self.size.height/4.0);
        CGPathAddLineToPoint(path, NULL, self.size.width/2.0,  -self.size.height/4.0);
        CGPathAddLineToPoint(path, NULL, -self.size.width/2.0, -self.size.height/4.0);
        CGPathAddLineToPoint(path, NULL, -self.size.width/2.0,  self.size.height/4.0);
        CGPathCloseSubpath  (path);
        self.physicsBody = [SKPhysicsBody bodyWithPolygonFromPath:path];
        self.physicsBody.affectedByGravity = YES;
        self.physicsBody.categoryBitMask = solidCategory;
        self.physicsBody.dynamic = YES;
        [self addChild:shape1];

        self.auxiliaryShapeNode  = [[SKSpriteNode alloc] init];
        CGPathMoveToPoint   (path_aux, NULL, 3*self.size.width/8.0, 0);
        CGPathAddLineToPoint(path_aux, NULL, self.size.width/2.0,   1.5*self.size.height/4.0);
        CGPathAddLineToPoint(path_aux, NULL, self.size.width/2.0,   -self.size.height/4.0);
        CGPathCloseSubpath  (path_aux);
        self.auxiliaryShapeNode.anchorPoint = CGPointMake(-3.0, 1.0/2.5);
        self.auxiliaryShapeNode.physicsBody = [SKPhysicsBody bodyWithPolygonFromPath:path_aux];
        self.auxiliaryShapeNode.physicsBody.dynamic = YES;
        self.auxiliaryShapeNode.physicsBody.categoryBitMask = solidCategory;


        [self addChild:self.auxiliaryShapeNode];
        [self.scene.physicsWorld addJoint:[SKPhysicsJointFixed jointWithBodyA:self.physicsBody bodyB:self.auxiliaryShapeNode.physicsBody anchor:self.position]];
        break;

其中 self 是我创建的自定义精灵节点，它有一个 SKSprite 节点作为辅助身体形状，因此形状可以由两个凸多边形组成，它按预期创建形状，但是当场景开始播放时关节没有按预期工作，并将小三角形从它开始的地方移开

Answer 1

我解决了我的问题，我实际上没有找到答案，但我想你可以说我解决了它

我意识到 Bodyjoint 的点只服从 x 坐标，但总是将 y 坐标移动到 0，所以我将 body 移动到 0,0 坐标，然后将 body 再次移动到它的位置以前的位置

    CGPoint *prevPosition = self.position;
    //positioning of the node so that the joint lands exactly 0,0
    self.position = CGPointMake(-3*self.size.width/8.0,0);

    CGPathMoveToPoint   (path, NULL, self.size.width/4.0,   self.size.height/4.0);
    CGPathAddLineToPoint(path, NULL, self.size.width/2.0,  -self.size.height/4.0);
    CGPathAddLineToPoint(path, NULL, -self.size.width/2.0, -self.size.height/4.0);
    CGPathAddLineToPoint(path, NULL, -self.size.width/2.0,  self.size.height/4.0);
    CGPathCloseSubpath  (path);
    self.physicsBody = [SKPhysicsBody bodyWithPolygonFromPath:path];
    self.physicsBody.affectedByGravity = YES;
    self.physicsBody.categoryBitMask = solidCategory;
    self.physicsBody.dynamic = YES;
    [self addChild:shape1];

    self.auxiliaryShapeNode  = [[SKSpriteNode alloc] init];
    //now we asssign the frame, the position does not matter as it is determined by the joint
    self.auxiliaryShapeNode.frame = CGRectMake(0,0,sel.size.width/8.0,self.height/2);
    self.auxiliaryShapeNode.anchor = CGPointMake(0,0.5);
    CGPathMoveToPoint   (path_aux, NULL, 0,0);
    CGPathAddLineToPoint(path_aux, NULL, self.auxiliaryShapeNode.size.width,   self.auxiliaryShapeNode.size.width/2.0);
    CGPathAddLineToPoint(path_aux, NULL, self.auxiliaryShapeNode.size.width, -self.auxiliaryShapeNode.size.width/2.0);
    CGPathCloseSubpath  (path_aux);
    self.auxiliaryShapeNode.physicsBody = [SKPhysicsBody bodyWithPolygonFromPath:path_aux];
    self.auxiliaryShapeNode.physicsBody.dynamic = YES;
    self.auxiliaryShapeNode.physicsBody.categoryBitMask = solidCategory;


    [self addChild:self.auxiliaryShapeNode];
    [self.scene.physicsWorld addJoint:[SKPhysicsJointFixed jointWithBodyA:self.physicsBody bodyB:self.auxiliaryShapeNode.physicsBody anchor:CGPointZero]];
    self.position=prevPosition;

所以，我设法以这种方式“让它工作”，希望它对某人有用