SpriteKit中精灵之间的碰撞

Question

我正在使用SpriteKit在XCode中制作一个游戏。游戏中有一个玩家，他必须避免不同类型的投射物。当玩家与投射物相撞时，分数发生变化，投射物消失。然而，当两个弹丸碰撞时，它们会反弹。我想让两个炮弹每次相撞时，它们表现得像什么都没发生过一样，并保持原来的轨迹。我该怎么办？

*注意：这并不是整个代码，重要的是它。

    import SpriteKit

    struct Physics {
        static let player : UInt32 = 1
        static let missileOne : UInt32 = 2
        static let missileTwo : UInt32 = 3
    }

class GameScene: SKScene, SKPhysicsContactDelegate {

    var player = SKSpriteNode(imageNamed: "p1.png")

    override func didMoveToView(view: SKView) {

        physicsWorld.contactDelegate = self

        player.position = CGPointMake(self.size.width/2, self.size.height/5)
        player.physicsBody = SKPhysicsBody(rectangleOfSize: player.size)
        player.physicsBody?.affectedByGravity = false
        player.physicsBody?.dynamic = false
        player.physicsBody?.categoryBitMask = Physics.player
        player.physicsBody?.collisionBitMask = Physics.missileOne
        player.physicsBody?.collisionBitMask = Physics.missileTwo

        var missileOneTimer = NSTimer.scheduledTimerWithTimeInterval(1, target: self, selector: Selector("SpawnMissileOne"), userInfo: nil, repeats: true)
        var missileTwoTimer = NSTimer.scheduledTimerWithTimeInterval(1.2, target: self, selector: Selector("SpawnMissileTwo"), userInfo: nil, repeats: true)

        self.addChild(player)
    }

    //When contact happens
func didBeginContact(contact: SKPhysicsContact) {
    var firstBody : SKPhysicsBody = contact.bodyA
    var secondBody : SKPhysicsBody = contact.bodyB

    if ((firstBody.categoryBitMask == Physics.player) && (secondBody.categoryBitMask == Physics.missileOne)) {

        CollisionWithMissileOne(firstBody.node as SKSpriteNode, missileOne: secondBody.node as SKSpriteNode)

    } else if ((firstBody.categoryBitMask == Physics.player) && (secondBody.categoryBitMask == Physics.missileTwo)){

        CollisionWithMissileTwo(firstBody.node as SKSpriteNode, missileTwo: secondBody.node as SKSpriteNode)

    } else if ((firstBody.categoryBitMask == Physics.missileOne)&&(secondBody.categoryBitMask == Physics.missileTwo)) {

        CollisionBetweenMissiles(firstBody.node as SKSpriteNode, missileTwo: secondBody.node as SKSpriteNode)

        } 

    }

//For Player and MissileOne
    func CollisionWithMissileOne(player: SKSpriteNode, missileOne: SKSpriteNode) {

        missileOne.removeFromParent()
    }

//For Player and MissileTwo
    func CollisionWithMissileOne(player: SKSpriteNode, missileTwo: SKSpriteNode) {

        missileTwo.removeFromParent()
    }

//For MissileOne and MissileTwo
        func CollisionBetweenMissiles(missileOne: SKSpriteNode, missileTwo: SKSpriteNode) {

        ???WHAT SHOULD I CODE HERE???

    }

}

Answer 1

令人困惑的是，碰撞BitMask用于定义哪些物理体在物理模型中相互作用。您真正想要的是联系测试位掩码。

此外，您的物理没有返回正确的值用于位掩码。作为纯整数，它们应该是1、2、4、8等。

这是你修改后的代码，希望可以正常工作，我已经在修改的地方做了注释。

 struct Physics {
        static let player : UInt32 = 1
        static let missileOne : UInt32 = 2
        static let missileTwo : UInt32 = 4 // to work properly as bit masks
    }

如果要检查与多种类型的物理的接触对象正文.categoryBitMask，则此更改是必需的。看看玩家.物理身体？.联系测试位掩码 = ...在 didMoveToView 中：

override func didMoveToView(view: SKView) {
    physicsWorld.contactDelegate = self
    // All your existing player-stuff is fine until...
    // contactTest, not collision but contact, also: use bitwise OR
    player.physicsBody?.contactTestBitMask = Physics.missileOne | Physics.missileTwo
    self.addChild(player)

    // It is not recommended to use NSTimer for SpriteKit, use SKActions instead
    let missileOneWait = SKAction.waitForDuration(1)
    let callSpawnOneAction = SKAction.runBlock({ self.spawnMissileOne() })
    let missileOneRepeat = SKAction.repeatActionForever(SKAction.sequence([missileOneWait, callSpawnOneAction]))
    runAction(missileOneRepeat)

    let missileTwoWait = SKAction.waitForDuration(1.2)
    let callSpawnTwoAction = SKAction.runBlock({ self.spawnMissileTwo() })
    let missileTwoRepeat = SKAction.repeatActionForever(SKAction.sequence([missileTwoWait, callSpawnTwoAction]))
    runAction(missileTwoRepeat)
}

几乎重写了开始接触一些我相信读起来和缩放得更好的东西：

func didBeginContact(contact: SKPhysicsContact) {
    var firstBody = contact.bodyA
    var secondBody = contact.bodyB

    // Rewritten with dynamic variables
    var playerNode : SKSpriteNode? {
        if firstBody.categoryBitMask == Physics.player {
            return firstBody.node as? SKSpriteNode
        } else if secondBody.categoryBitMask == Physics.player {
            return secondBody.node as? SKSpriteNode
        }
        return nil
    }

    // If you want to handle contact between missiles you need to split this 
    // into two different variables
    var missileNode : SKSpriteNode? {
        let bitmask1 = firstBody.categoryBitMask
        let bitmask2 = secondBody.categoryBitMask

        if bitmask1 == Physics.missileOne || bitmask1 == Physics.missileTwo {
            return firstBody.node as? SKSpriteNode
        } else if bitmask2 == Physics.missileOne || bitmask2 == Physics.missileTwo {
            return secondBody.node as? SKSpriteNode
        }
        return nil
    }

    if playerNode != nil {
        collisionBetweenPlayer(playerNode, missile: missileNode)
    }
} 

那么你只需要一个功能来联系导弹和玩家:

func collisionBetweenPlayer(player: SKSpriteNode?, missile: SKSpriteNode?) {
    missile?.removeFromParent()
}