ios - SKShapeNode 检测两条线的交点

Question

我正在开发一个应用程序，我正在根据用户手指的触摸来绘制线条。一旦收到触摸结束事件，该行将转换为最后一条路径。当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。

Answer 1

碰撞不是那样工作的。如果您使用物理来移动节点的位置，您只会注册碰撞。在(或跨越)现有物理体上创建新物理体不会发生碰撞。

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