我正在用 SpriteKit 制作一个简单的游戏,我有一个滚动背景。简单的情况是,当游戏场景加载时,几张背景图像彼此相邻放置,然后当图像滚出屏幕时,图像水平移动。这是来 self 的游戏场景的 didMoveToView
方法的代码。
// self.gameSpeed is 1.0 and gradually increases during the game
let backgroundTexture = SKTexture(imageNamed: "Background")
var moveBackground = SKAction.moveByX(-self.frame.size.width, y: 0, duration: (20 / self.gameSpeed))
var replaceBackground = SKAction.moveByX(self.frame.size.width, y: 0, duration: 0)
var moveBackgroundForever = SKAction.repeatActionForever(SKAction.sequence([moveBackground, replaceBackground]))
for var i:CGFloat = 0; i < 2; i++ {
var background = SKSpriteNode(texture: backgroundTexture)
background.position = CGPoint(x: self.frame.size.width / 2 + self.frame.size.width * i, y: CGRectGetMidY(self.frame))
background.size = self.frame.size
background.zPosition = -100
background.runAction(moveBackgroundForever)
self.addChild(background)
}
现在我想在游戏的某些点提高滚动背景的速度。可以看到背景水平滚动的时长设置为(20/self.gameSpeed)
。显然这是行不通的,因为这段代码只运行一次,因此移动速度永远不会更新以说明 self.gameSpeed
变量的新值。
所以,我的问题很简单:如何根据 self.gameSpeed
变量提高背景图片的移动速度(缩短持续时间)?
谢谢!
最佳答案
您可以使用 gameSpeed
变量来设置背景的速度。为此,首先,您需要引用您的两个背景片段(如果需要,可以引用更多):
class GameScene: SKScene {
lazy var backgroundPieces: [SKSpriteNode] = [SKSpriteNode(imageNamed: "Background"),
SKSpriteNode(imageNamed: "Background")]
// ...
}
现在您需要您的 gameSpeed
变量:
var gameSpeed: CGFloat = 0.0 {
// Using a property observer means you can easily update the speed of the
// background just by setting gameSpeed.
didSet {
for background in backgroundPieces {
// Minus, because the background is moving from left to right.
background.physicsBody!.velocity.dx = -gameSpeed
}
}
}
然后在 didMoveToView
中正确定位每一 block 。此外,要使此方法起作用,每个背景片段都需要一个物理体,以便您可以轻松更改其速度。
override func didMoveToView(view: SKView) {
for (index, background) in enumerate(backgroundPieces) {
// Setup the position, zPosition, size, etc...
background.physicsBody = SKPhysicsBody(rectangleOfSize: background.size)
background.physicsBody!.affectedByGravity = false
background.physicsBody!.linearDamping = 0
background.physicsBody!.friction = 0
self.addChild(background)
}
// If you wanted to give the background and initial speed,
// here's the place to do it.
gameSpeed = 1.0
}
您可以在 update
中更新 gameSpeed
,例如 gameSpeed += 0.5
。
最后,在 update
中,您需要检查背景片段是否离开屏幕(向左)。如果有,则需要将其移至背景片段链的末尾:
override func update(currentTime: CFTimeInterval) {
for background in backgroundPieces {
if background.frame.maxX <= 0 {
let maxX = maxElement(backgroundPieces.map { $0.frame.maxX })
// I'm assuming the anchor of the background is (0.5, 0.5)
background.position.x = maxX + background.size.width / 2
}
}
}
关于ios - 逐渐提高 SpriteKit 中滚动背景的速度,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/30226379/