ios - Swift:如何让子弹在玩家武器上产生？

Question

我有一个创建玩家的 CharacterCreator 类，在它里面我有这些函数让玩家射击:

func shoot(scene: SKScene) {
    if (playerArmed) {
        let bullet = self.createBullet()
        scene.addChild(bullet)
        bullet.position = playerWeaponBarrel.position
        bullet.physicsBody?.velocity = CGVectorMake(200, 0)
    }
}

func createBullet() -> SKShapeNode {
    let bullet = SKShapeNode(circleOfRadius: 2)
    bullet.fillColor = SKColor.blueColor()
    bullet.physicsBody = SKPhysicsBody(circleOfRadius: bullet.frame.height / 2)
    bullet.physicsBody?.affectedByGravity = false
    bullet.physicsBody?.dynamic = true
    bullet.physicsBody?.categoryBitMask = PhysicsCategory.Bullet
    bullet.physicsBody?.contactTestBitMask = PhysicsCategory.Ground
    bullet.physicsBody?.collisionBitMask = PhysicsCategory.Ground
    return bullet
}

playerWeaponBarrel 子节点是子弹应该生成的地方。当我在 GameScene 调用 shoot() 函数时会发生什么:

override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
    /* Called when a touch begins */
    for touch: AnyObject in touches {
        let location = touch.locationInNode(self)
        let touchedNode = self.nodeAtPoint(location)

        if (touchedNode == fireButton) {
            Player.shoot(self.scene!)
        }

它只是不会在 playerWeaponBarrel 上创建子弹。我该如何做到这一点？

Answer 1

你的问题是 playerWeaponBarrel.position 是相对于它的 super 节点的，它可能是 player。但是您希望 bullet 绝对位于场景中，而不是相对于 player。因此，您需要做的是将 playerWeaponBarrel.position 从其本地坐标系转换为 scene 坐标系:

bullet.position = scene.convertPoint(playerWeaponBarrel.position, fromNode: playerWeaponBarrel.parent!)