Question

嗨我需要随机地在屏幕上沿x轴底部生成我的精灵气球。我使用了Ray Wenderliches网站上的代码，但当我点击开始产卵的按钮时，他们不会产卵？

 @implementation MyScene2



 - (void)addMonster {

// Create sprite
SKSpriteNode * monster = [SKSpriteNode spriteNodeWithImageNamed:@"balloon11.png"];

// Determine where to spawn the monster along the X axis
int minX = monster.size.height / 2;
int maxX = self.frame.size.height - monster.size.height / 2;
int rangeX = maxX - minX;
int actualX = (arc4random() % rangeX) + minX;

// Create the monster slightly off-screen along the right edge,
// and along a random position along the X axis as calculated above
monster.position = CGPointMake(self.frame.size.width + monster.size.width/2, actualX);
[self addChild:monster];

// Determine speed of the monster
int minDuration = 2.0;
int maxDuration = 4.0;
int rangeDuration = maxDuration - minDuration;
int actualDuration = (arc4random() % rangeDuration) + minDuration;

   // Create the actions
SKAction * actionMove = [SKAction moveTo:CGPointMake(-monster.size.width/2, actualX)   
 duration:actualDuration];
SKAction * actionMoveDone = [SKAction removeFromParent];
[monster runAction:[SKAction sequence:@[actionMove, actionMoveDone]]];

}


  - (void)updateWithTimeSinceLastUpdate:(CFTimeInterval)timeSinceLast {

  self.lastSpawnTimeInterval += timeSinceLast;
  if (self.lastSpawnTimeInterval > 1) {
    self.lastSpawnTimeInterval = 0;
     [self addMonster];
   }
 }



  - (void)update:(NSTimeInterval)currentTime {
 // Handle time delta.
 // If we drop below 60fps, we still want everything to move the same distance.
 CFTimeInterval timeSinceLast = currentTime - self.lastUpdateTimeInterval;
 self.lastUpdateTimeInterval = currentTime;
 if (timeSinceLast > 1) { // more than a second since last update
    timeSinceLast = 1.0 / 60.0;
    self.lastUpdateTimeInterval = currentTime;
    }

  [self updateWithTimeSinceLastUpdate:timeSinceLast];

 }

Answer 1

您的主要问题在于以下代码：

monster.position = CGPointMake(self.frame.size.width + monster.size.width/2 , actualX);

该方法的工作方式如下：CGPointMake( x_coord , y_coord );。

现在，您将x值设置为帧的宽度加上精灵的宽度，因此这将导致精灵在屏幕上生成。你给y坐标随机化的值。相反，使用

CGPointMake(actualX , self.frame.size.height);

此代码存在另一个问题。这些坐标基于视图，但monster.position基于SKScene。 SKScene来源通常与视图的原点不匹配。所以你必须这样做：

monster.position = [CGPointMake(actualX , self.frame.size.height); locationInNode: self];

另外，我注意到您使用frame.size.width表示预期的Y轴坐标，frame.size.height表示预期的X轴坐标。宽度用于x，高度用于y，因此请确保正确使用它们。

在x轴上随机产生精灵

1 个答案: