SceneKit基础

Question

我刚刚开始用SceneKit做实验。尝试一个非常简单的代码来创建一个物体，给它分配物理，用一个抽头给它一个速度。到目前为止，我能够创造它，应用物理学。我可以给它速度，但不能实现这一点与点击。我做错了什么？我使用的技术与在SpriteKit中使用的技术相同，但在SceneKit中不起作用。请帮帮忙。

class GameViewController: UIViewController, SCNSceneRendererDelegate, SCNPhysicsContactDelegate {
let scene = SCNScene()

let shipNode = SCNNode()

let sceneView = SCNScene()

var cameraNode = SCNNode()
var floor = SCNFloor()
var floornod = SCNNode()

override func viewDidLoad() {
    super.viewDidLoad()

    let sceneView = self.view as SCNView
    sceneView.scene = scene
    sceneView.backgroundColor = SKColor.blueColor()
    sceneView.showsStatistics = true


    sceneView.scene?.physicsWorld.gravity = SCNVector3Make(0, -70, 0)
    sceneView.scene?.physicsWorld.speed = 1.0
    sceneView.delegate = self
    sceneView.jitteringEnabled = true
    sceneSetup()
    sceneView.pointOfView = cameraNode


    let ship = SCNScene(named: "art.scnassets/sphere.dae")!

    let shipNode = ship.rootNode.childNodeWithName("Sphere", recursively: true)!

    shipNode.position = SCNVector3Make(0, 50, 300)
    shipNode.scale = SCNVector3Make(10, 10, 10)
    shipNode.geometry?.firstMaterial?.diffuse.contents = UIImage(named: "ball.jpg")
    shipNode.physicsBody = SCNPhysicsBody(type: SCNPhysicsBodyType.Dynamic, shape: nil)
    shipNode.physicsBody?.restitution = 0.9
    shipNode.physicsBody?.velocity = SCNVector3Make(0, 100, 10)
    scene.rootNode.addChildNode(shipNode)
    println(shipNode.physicsBody?.velocity.y)
}
override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {
    shipNode.physicsBody?.velocity = SCNVector3Make(0, 200, 20) // code not working
    println(shipNode.physicsBody?.velocity.y) // prints nil instead of 200.00
}

    func sceneSetup() {

    cameraNode.camera = SCNCamera()
    cameraNode.camera?.zNear = 0.01
    cameraNode.camera?.zFar = 800
    cameraNode.camera?.xFov = 45
    cameraNode.camera?.yFov = 75


    cameraNode.rotation = SCNVector4Make(1, 0, 0, -25 * 0.017453293)
    cameraNode.position = SCNVector3Make(0, 150, 500)
    scene.rootNode.addChildNode(cameraNode)

    floornod.geometry = floor
    floornod.geometry?.firstMaterial?.diffuse.contents = "wood1.png"
    floornod.geometry?.firstMaterial?.locksAmbientWithDiffuse = true
    floornod.geometry?.firstMaterial?.diffuse.wrapS = SCNWrapMode.Repeat
    floornod.geometry?.firstMaterial?.diffuse.wrapT = SCNWrapMode.Repeat
    floornod.geometry?.firstMaterial?.diffuse.mipFilter = SCNFilterMode.Linear
    floornod.physicsBody = SCNPhysicsBody(type: SCNPhysicsBodyType.Static, shape: nil)
    floornod.position = SCNVector3Make(0, 0, 0)

    scene.rootNode.addChildNode(floornod)

}

}

第一个println给出的结果是100.00。touchesBegan中的println在每次点击时都会给出零的结果。

任何帮助都是非常感谢的。谢谢。

Answer 1

在viewDidLoad方法中使用let shipNode = ...定义一个新的局部变量。这个人得到了一个物理的身体，然后被放到了场景中。

这与您定义为类的一部分的实例变量shipNode是分开的。因此，当您在touchesBegan中访问它时，它没有物理体，并且可选的链接会导致查询其返回速度的整个表达式为零。

想必您希望摆脱viewDidLoad中的viewDidLoad，这样您就可以配置实例变量而不是跟踪它们。