在 SpriteKit 中检测节点半径内的触摸

Question

我的 SpriteKit 游戏中有一个玩家对象，目前我正在使用以下代码移动它：

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    if (touches.count == 1)
    {
        [self touchesMoved:touches withEvent:event];
    }
}


-(void)touchesMoved:(NSSet*)touches withEvent:(UIEvent*)event
{
    if (touches.count == 1)
    {
        [_player runAction:[SKAction moveTo:[[touches anyObject] locationInNode:self] duration:0.01]];
    }
}

但我只想在触摸在位置的特定范围内时移动播放器节点。

Answer 1

由于您似乎只关心触摸与您的_player 对象的距离，我会将半径检测逻辑移至您的_player 对象并使用SKRegion 来处理它。

注意： 如果您需要知道您的触摸是否在多个节点的半径内，那么您可能需要使用this question 中的方法。 p>

要使用SKRegion 来确定您的触摸是否在_player 的某个半径内，请将SKRegion 实例添加到您的_player 对象并使用您想要的半径对其进行初始化。在[_player init] 或任何对您的项目最有意义的地方：

self.touchRegion = [[SKRegion alloc] initWithRadius:radius];

然后添加一个方法来确定一个点是否在该区域内：

- (BOOL)pointIsInTouchRegion:(CGPoint)point {
    return [self.touchRegion containsPoint: point];
}

接下来将您的 touchesMoved 方法更改为：

-(void)touchesMoved:(NSSet*)touches withEvent:(UIEvent*)event
{
    if (touches.count == 1)
    {
        UITouch *touch = [touches anyObject];
        CGPoint point = [self locationInNode:_player]; // NOTE: It's important to use _player here!
        if ([_player pointIsInTouchRegion: point]) {
            [_player runAction:[SKAction moveTo:[[touches anyObject] locationInNode:self] duration:0.01]];
        }
    }
}

注意： 在[self locationInNode:_player]; 中使用_player 至关重要，因为您的SKRegion 将在_player 节点的坐标系中定义。

还有一点需要注意：您实际上不必将所有这些逻辑都放在_player 中，这正是我的做法。您可以轻松地将 SKRegion 存储在场景的类中，然后直接调用 [region containsPoint: point]。

---

更新：iOS 7 方法

对 iOS 7 执行此操作的主要区别在于，您需要存储您感兴趣的实际半径而不是 SKRegion（因为它仅在 iOS 8 中可用），然后在 @ 中自己进行计算987654342@。

因此，在_player 中，将您的触摸半径设置为您之前设置touchRegion 的位置：

self.touchRadius = radius

然后更改pointIsInTouchRegion: 方法，让它进行实际距离计算。

- (BOOL)pointIsInTouchRegion:(CGPoint)point {
    CGPoint centerOfNode = CGPointMake(self.frame.size.width / 2.0, self.frame.size.height / 2.0); // NOTE: If this is in an SKSpriteNode, you might want to use self.anchorPoint instead
    CGFloat distanceToCenter = return hypotf(point.x - centerOfNode.x, point.y - centerOfNode.y);
    return (distanceToCenter <= self.radius);
}

touchesMoved 中的代码不需要任何更改。

Answer 2

以下演示如何 1) 选择距触摸事件指定距离内的精灵，以及 2) 将选定的精灵拖放到新位置。

@interface MyScene()

@property (weak) SKSpriteNode *selectedNode;

@end

@implementation MyScene

-(id)initWithSize:(CGSize)size {    
    if (self = [super initWithSize:size]) {
        /* Setup your scene here */

        self.backgroundColor = [SKColor colorWithRed:0.15 green:0.15 blue:0.3 alpha:1.0];

        // Add three sprites to scene
        SKSpriteNode *sprite = [SKSpriteNode spriteNodeWithColor:[SKColor blueColor] size:CGSizeMake(32, 32)];
        sprite.name = @"Blue";
        sprite.position = CGPointMake(CGRectGetMidX(self.frame),
                                      CGRectGetMidY(self.frame)-64);
        [self addChild:sprite];

        sprite = [SKSpriteNode spriteNodeWithColor:[SKColor redColor] size:CGSizeMake(32, 32)];
        sprite.name = @"Red";
        sprite.position = CGPointMake(CGRectGetMidX(self.frame),
                                      CGRectGetMidY(self.frame) + 64);
        [self addChild:sprite];


        sprite = [SKSpriteNode spriteNodeWithColor:[SKColor greenColor] size:CGSizeMake(32, 32)];
        sprite.name = @"Green";
        sprite.position = CGPointMake(CGRectGetMidX(self.frame),
                                      CGRectGetMidY(self.frame));

        [self addChild:sprite];
    }
    return self;
}

#define kRadius     64

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
    _selectedNode = nil;
    CGFloat minDistance = kRadius+1;
    for (UITouch *touch in touches) {
        CGPoint location = [touch locationInNode:self];
        for (SKSpriteNode *node in self.children) {
            CGFloat dx = location.x - node.position.x;
            CGFloat dy = location.y - node.position.y;
            // Compute distance from sprite to tap point
            CGFloat distance = sqrtf(dx*dx+dy*dy);
            if (distance <= kRadius) {
                if (distance < minDistance) {
                    // Select the closest node so far
                    _selectedNode = node;
                    minDistance = distance;
                }
            }
        }
    }
}

- (void) touchesMoved:(NSSet*)touches withEvent:(UIEvent*)event
{
    UITouch *touch = [touches anyObject];
    CGPoint location = [touch locationInNode:self];
    if (_selectedNode) {
        // Move selected node to current touch position
        _selectedNode.position = location;
    }
}

- (void) touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
    // Unselect node
    _selectedNode = nil;
}

- (void) update:(CFTimeInterval)currentTime {
    /* Called before each frame is rendered */
}

@end

Answer 3

我认为你应该添加这个，如果我误解了你的问题，请原谅我：

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
   CGPoint point = [touch locationInView:self.view];

if (touches.count == 1) && (point.x == yourObjectsXPosition) && (point.y ==  yourObjectsYPosition) 

     {
    [self touchesMoved:touches withEvent:event];
     }
}