SKShapeNode 检测两条线的交点

Posted 2023-03-16

【中文标题】SKShapeNode 检测两条线的交点

【英文标题】：SKShapeNode Detect Two Lines Intersection

【发布时间】：2015-05-30 09:48:15

【问题描述】：

我正在开发一个应用程序，我正在根据用户手指的用户触摸画线。一旦收到触摸结束事件，该行将转换为最后一条路径。当接收到新的触摸开始事件时，将绘制一条名为“当前路径”节点的新线。我为具有相反接触位掩码的两条线添加了一个物理体，但我无法接收碰撞事件。 以下是我的代码：

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event

    UITouch* touch = [touches anyObject];
    CGPoint positionInScene = [touch locationInNode:self];
    currentPath = CGPathCreateMutable();
    currentPathNode = [self newLineNodeWithFillColor :  CURRENT_LINE_COLOR];
    CGPathMoveToPoint(currentPath, NULL, positionInScene.x, positionInScene.y);
    currentPathNode.path = currentPath;
    [self addChild:currentPathNode];
    uint32_t contactBitMask = circleCategory | lastPathCategory;
    [self addPhysicsBodyForLine:currentPathNode withCategoryBitMask:drawPathCategory withContactBitMask:contactBitMask];

- (void)touchesMoved:(NSSet*)touches withEvent:(UIEvent*)event

    UITouch* touch = [touches anyObject];
    CGPoint positionInScene = [touch locationInNode:self];
    CGPathAddLineToPoint(currentPath, NULL, positionInScene.x, positionInScene.y);
    currentPathNode.path = currentPath;
    uint32_t contactBitMask = lastPathCategory;
    [self addPhysicsBodyForLine:currentPathNode withCategoryBitMask:drawPathCategory withContactBitMask:contactBitMask];

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event

    if(lastPath == nil)
        lastPath = CGPathCreateMutable();
    
    CGPathAddPath(lastPath, nil, currentPath);
    [lastPathNode removeFromParent];
    if(currentPathNode != nil)
        [currentPathNode removeFromParent];
        currentPathNode = nil;
    
    lastPathNode = [self newLineNodeWithFillColor : LAST_LINE_COLOR];
    lastPathNode.path = lastPath;
    [self addChild:lastPathNode];
    [self addPhysicsBodyForLine:lastPathNode withCategoryBitMask:lastPathCategory withContactBitMask:drawPathCategory];
    CGPathRelease(currentPath);
  
- (void) addPhysicsBodyForLine:(SKShapeNode*)node withCategoryBitMask:(uint32_t)category withContactBitMask:(uint32_t)contactBitMask
    node.physicsBody =  [SKPhysicsBody bodyWithEdgeChainFromPath:node.path];
    node.physicsBody.categoryBitMask    = category;
    node.physicsBody.contactTestBitMask = contactBitMask;
    node.physicsBody.collisionBitMask = contactBitMask;
    node.physicsBody.dynamic          = YES;
    node.physicsBody.usesPreciseCollisionDetection = YES;

但是没有检测到碰撞？任何解决方案。

【参考方案1】：

碰撞不能这样工作。如果您使用物理移动节点的位置，您只会记录碰撞。在已经存在的物理体上方（或跨过）创建新的物理体不会记录碰撞。

您可以在每次绘制新路径时使用-(BOOL)intersectsNode:(SKNode *)node 来检查新节点是否与任何其他节点相交。