SceneKit - 在另一个 SCNNode 上添加 SCNNode [英] SceneKit - adding SCNNode on another SCNNode

问题描述

我试图将球体放在盒子的顶部，但位置很奇怪:球半隐藏在盒子里.我尝试更改框和球体枢轴，但没有帮助.代码如下:

I'm trying to put sphere on top of the box, but the position is strange: Ball is half hidden inside box. I tried to change box and sphere pivot, but it didn't help. Here's the code:

    let cubeGeometry = SCNBox(width: 10, height: 10, length: 10, 
    chamferRadius: 0)
    let cubeNode = SCNNode(geometry: cubeGeometry)
    //cubeNode.pivot = SCNMatrix4MakeTranslation(0, 1, 0)
    scene.rootNode.addChildNode(cubeNode)

    let ballGeometry = SCNSphere(radius: 1)
    let ballNode = SCNNode(geometry: ballGeometry)
    ballNode.pivot = SCNMatrix4MakeTranslation(0.5, 0, 0.5)
    ballNode.position = SCNVector3Make(0, 5, 0)
    cubeNode.addChildNode(ballNode)`

结果:

我做错了什么?如何将球放在盒子的正上方?

what I'm doing wrong? How to put the ball right on the top side of the box?

更新:如果我添加立方体而不是球，它看起来不错

UPDATE: If I add Cube instead of ball, it looks good as I want

推荐答案

您需要通过 cube-height/2 + sphere-radius 在 Y 轴上平移.因此你应该有:

You need to translate on the Y-axis by cube-height/2 + sphere-radius. Thus you should have:

ballNode.position = SCNVector3Make(0, 6, 0)

截图如下:

相关完整代码:

override func viewDidLoad() {
    super.viewDidLoad()

    // create a new scene
    let scene = SCNScene()

    let cubeGeometry = SCNBox(width: 10, height: 10, length: 10,
                              chamferRadius: 0)
    cubeGeometry.firstMaterial?.diffuse.contents = UIColor.yellow
    let cubeNode = SCNNode(geometry: cubeGeometry)
    scene.rootNode.addChildNode(cubeNode)

    let ballGeometry = SCNSphere(radius: 1)
    ballGeometry.firstMaterial?.diffuse.contents = UIColor.green
    let ballNode = SCNNode(geometry: ballGeometry)
    ballNode.position = SCNVector3Make(0, 6, 0)
    cubeNode.addChildNode(ballNode)

    // retrieve the SCNView
    let scnView = self.view as! SCNView

    // set the scene to the view
    scnView.scene = scene

    // allows the user to manipulate the camera
    scnView.allowsCameraControl = true

    // show statistics such as fps and timing information
    scnView.showsStatistics = true

    // configure the view
    scnView.backgroundColor = UIColor.gray
}

更新:为什么是半径而不是半径/2

在 Xcode 中的场景编辑器中查看此屏幕截图.立方体的原始位置是 (0, 0, 0) 球的位置也是如此；因此球需要移动 r 而不是 r/2；对于 r/2，高度为 r/2 的球的下部将仍在立方体内.您可以在编辑器中添加一个立方体和球体，如下面的场景所示，这应该有助于澄清.

See this screenshot from the Scene Editor in Xcode. The original position of cube is (0, 0, 0) and so is that of the ball; hence the ball needs to be moved by r and not r / 2; with r / 2 the lower section of the ball with height r/2 will be still inside the cube. You can just add a cube and sphere as in the scene below in the editor and that should help clarify.

这篇关于SceneKit - 在另一个 SCNNode 上添加 SCNNode的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！