问雪碧包bodyAtPoint和bodyInRect返回不正确的值？
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Stack Overflow用户

提问于 2013-11-09 14:10:28

回答 1查看 680关注 0票数 5

我创建了一个非常简单的示例代码，只有一个场景，一个sprite节点20x20px，在屏幕上的点0.0。当我调用scene.physicsWorld bodyAtPoint时，它会返回这个节点，即使是在点，例如: 34x34。但是在35x35点处，它返回null。所以基本上在两个轴上从0px到34px的所有点都返回这个节点，从35px开始，它不再返回它。如果sprite在20px 20px上明显结束，你知道原因是什么吗？在bodyInRect中也可以看到同样的行为。

以下是示例代码：

-(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];
    self.physicsWorld.gravity = CGVectorMake(0, 0);

    SKSpriteNode *node = [[SKSpriteNode alloc] initWithColor:[UIColor whiteColor] size:CGSizeMake(20, 20)];
    node.position = CGPointMake(10, 10);

    node.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:CGSizeMake(20, 20)];
    [self addChild:node];

}
return self;
}

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

for (UITouch *touch in touches) {
    CGPoint location = [touch locationInNode:self];
    if([self.physicsWorld bodyAtPoint:location])
    {
        NSLog(@"Detected at point: %f %f", location.x, location.y);
    }else{
        NSLog(@"No node at point: %f %f", location.x, location.y);
    }
}
}

下面是控制台日志：

2013-11-09 15:05:52.822 SKTest[43143:70b] Detected at point: 2.000000 1.000000
2013-11-09 15:05:56.274 SKTest[43143:70b] Detected at point: 3.000000 7.000000
2013-11-09 15:05:57.006 SKTest[43143:70b] Detected at point: 3.000000 11.000000
2013-11-09 15:05:58.199 SKTest[43143:70b] Detected at point: 3.000000 12.000000
2013-11-09 15:05:58.918 SKTest[43143:70b] Detected at point: 3.000000 14.000000
2013-11-09 15:05:59.785 SKTest[43143:70b] Detected at point: 3.000000 17.000000
2013-11-09 15:06:00.685 SKTest[43143:70b] Detected at point: 3.000000 20.000000
2013-11-09 15:06:01.565 SKTest[43143:70b] Detected at point: 3.000000 22.000000
2013-11-09 15:06:02.915 SKTest[43143:70b] Detected at point: 3.000000 25.000000
2013-11-09 15:06:04.285 SKTest[43143:70b] Detected at point: 3.000000 30.000000
2013-11-09 15:06:05.387 SKTest[43143:70b] Detected at point: 3.000000 34.000000
2013-11-09 15:06:08.492 SKTest[43143:70b] No node at point: 4.000000 38.000000
2013-11-09 15:06:12.499 SKTest[43143:70b] Detected at point: 4.000000 5.000000
2013-11-09 15:06:13.240 SKTest[43143:70b] Detected at point: 6.000000 5.000000
2013-11-09 15:06:13.881 SKTest[43143:70b] Detected at point: 10.000000 5.000000
2013-11-09 15:06:15.064 SKTest[43143:70b] Detected at point: 12.000000 5.000000
2013-11-09 15:06:16.120 SKTest[43143:70b] Detected at point: 14.000000 5.000000
2013-11-09 15:06:16.873 SKTest[43143:70b] Detected at point: 16.000000 5.000000
2013-11-09 15:06:17.582 SKTest[43143:70b] Detected at point: 18.000000 5.000000
2013-11-09 15:06:18.066 SKTest[43143:70b] Detected at point: 21.000000 5.000000
2013-11-09 15:06:18.966 SKTest[43143:70b] Detected at point: 24.000000 5.000000
2013-11-09 15:06:19.585 SKTest[43143:70b] Detected at point: 31.000000 5.000000
2013-11-09 15:06:20.531 SKTest[43143:70b] Detected at point: 35.000000 5.000000
2013-11-09 15:06:22.581 SKTest[43143:70b] No node at point: 36.000000 4.000000
2013-11-09 15:06:26.560 SKTest[43143:70b] Detected at point: 19.000000 16.000000
2013-11-09 15:06:27.933 SKTest[43143:70b] Detected at point: 20.000000 17.000000
2013-11-09 15:06:29.856 SKTest[43143:70b] Detected at point: 25.000000 19.000000
2013-11-09 15:06:31.487 SKTest[43143:70b] Detected at point: 26.000000 22.000000
2013-11-09 15:06:33.850 SKTest[43143:70b] Detected at point: 29.000000 27.000000
2013-11-09 15:06:35.492 SKTest[43143:70b] Detected at point: 31.000000 29.000000
2013-11-09 15:06:36.854 SKTest[43143:70b] Detected at point: 35.000000 32.000000
2013-11-09 15:06:40.004 SKTest[43143:70b] No node at point: 40.000000 34.000000

这有没有可能是一个苹果的bug，在nodeAtPoint和nodeInRect中都有？这很难让人相信。但是代码太短了，我看不出这里会有什么错误。任何帮助都将不胜感激。

ios

ios7

sprite-kit

skphysicsbody

sknode

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回答 1

Stack Overflow用户

发布于 2013-11-09 22:26:12

我对此做了一些实验。当我放大精灵时，我注意到身体区域似乎比精灵更大。我不得不除以1.15的精灵大小，以获得身体直立，以大致匹配显示的精灵在所有4个方面。不过，我不知道为什么。我从来没有在游戏性方面有过问题，所以也许nodeAtPoint有一个阈值范围？

SKSpriteNode *node = [SKSpriteNode spriteNodetWithColor:[SKColor whiteColor]
                                                   size:CGSizeMake(200, 200)];
node.position = CGPointMake(200, 200);

CGRect bodySize = CGSizeMake(node.size.width / 1.15, node.size.height / 1.15);
node.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:bodySize];
[self addChild:node];