打开和关闭物理

Question

我正在尝试解决一个精灵节点可以在平台上跳跃但不能向下跳的问题。我尝试使用此代码：

override func didMove(to view: SKView) {
    if (thePlayer.position.y > stonePlatform1.position.y) ==  true {
        stonePlatform1.physicsBody = SKPhysicsBody(rectangleOf: CGSize(width: stonePlatform.size.width * 0.9, height: stonePlatform.size.height * 0.75))
        stonePlatform1.physicsBody!.isDynamic = false
        stonePlatform1.physicsBody!.affectedByGravity = false
        stonePlatform1.physicsBody!.categoryBitMask = BodyType.object.rawValue
        stonePlatform1.physicsBody!.contactTestBitMask = BodyType.object.rawValue
        stonePlatform1.physicsBody!.restitution = 0.4
    }
}

这个想法是在玩家在平台上方时打开平台的物理主体。但是，当我使用此代码时，物理学根本不起作用。事实上，我尝试使用这段代码：

override func didMove(to view: SKView) {
    if (thePlayer.position.y < stonePlatform1.position.y) ==  true {
        stonePlatform1.physicsBody = SKPhysicsBody(rectangleOf: CGSize(width: stonePlatform.size.width * 0.9, height: stonePlatform.size.height * 0.75))
        stonePlatform1.physicsBody!.isDynamic = false
        stonePlatform1.physicsBody!.affectedByGravity = false
        stonePlatform1.physicsBody!.categoryBitMask = BodyType.object.rawValue
        stonePlatform1.physicsBody!.contactTestBitMask = BodyType.object.rawValue
        stonePlatform1.physicsBody!.restitution = 0.4
    }
}

物理学也没有开启。如果不存在 IF 语句，则物理始终有效。

Answer 1

您可以在此平台上使用节点速度，如下所示：

SpriteKit - Swift 3 代码：

private var up1 : SKSpriteNode!
private var down1 : SKSpriteNode!
private var down2 : SKSpriteNode!
private var player : SKSpriteNode!

override func didMove(to view: SKView) {
    up1 = self.childNode(withName: "up1") as! SKSpriteNode
    down1 = self.childNode(withName: "down1") as! SKSpriteNode
    down2 = self.childNode(withName: "down2") as! SKSpriteNode
    player = self.childNode(withName: "player") as! SKSpriteNode
    up1.physicsBody?.categoryBitMask = 0b0001 // Mask for UoPlatforms
    down1.physicsBody?.categoryBitMask = 0b0010 // Mask for downPlatforms
    down2.physicsBody?.categoryBitMask = 0b0010 // Same mask
}

override func update(_ currentTime: TimeInterval) {
    player.physicsBody?.collisionBitMask = 0b0000 // Reset the mask

    // For UP only Platform
    if (player.physicsBody?.velocity.dy)! < CGFloat(0.0) {
        player.physicsBody?.collisionBitMask |= 0b0001 // The pipe | operator adds the mask by binary operations
    }

    // For Down only platforms
    if (player.physicsBody?.velocity.dy)! > CGFloat(0.0) {
        player.physicsBody?.collisionBitMask |= 0b0010  // The pipe | operator adds the mask by binary operations
    }

}

示例源代码：https://github.com/Maetschl/SpriteKitExamples/tree/master/PlatformTest

示例显示： 绿色平台 -> 仅向下 红色平台 -> 仅向上

Answer 2

您可以尝试从nil 的物理体开始，然后在玩家位于其上方后为其设置物理值。此外，这种代码应该在更新函数中。将它放在 didMove 中只会让它被调用一次。

override func update(_ currentTime: TimeInterval){
 if (thePlayer.position.y < stonePlatform1.position.y) && stonePlatform1.physicsBody != nil {
       stonePlatform1.physicsBody = nil
 }else if (thePlayer.position.y > stonePlatform1.position.y) && stonePlatform1.physicsBody == nil{
    setPhysicsOnPlatform(stonePlatform1)
 }
}

func setPhysicsOnPlatform(_ platform: SKSpriteNode){
   platform.physicsBody = SKPhysicsBody(rectangleOf: CGSize(width: stonePlatform.size.width * 0.9, height: stonePlatform.size.height * 0.75))
   ...
   //the rest of your physics settings
}

您还应该对播放器的高度和锚点进行一些处理。否则，如果您的 anchorPoint 为 (0,0) 并且玩家在平台的中途，则会应用物理并且会出现不希望的结果。