ios - 如何将 SKScene 添加到 SCNNode 平面？

Question

我已经完成了 raywenderlich.com 教程 Building a Museum App with ARKit 2. 我试图修改这个应用程序以放置一个 SKScene 在 anchor 图像而不是 AVPlayer 上。

我真正想做的是在图像上放置一个 SKShapeNode，但经过研究后我似乎必须创建一个 SKScene，添加 SKShapeNode 到 SKScene，然后将 SKScene 添加到 SCNPlane。

You can set a value for this property using any of the following types:

• A color (NSColor/UIColor or CGColor), specifying a uniform color for the material’s surface

• A number (NSNumber), specifying a uniform scalar value for the material's surface (useful for physically based properties such as metalness)

• An image (NSImage/UIImage or CGImage), specifying a texture to be mapped across the material’s surface

• An NSString or NSURL object specifying the location of an image file

• A video player (AVPlayer) or live video capture preview (AVCaptureDevice, in iOS only)

• A Core Animation layer (CALayer)

• A texture (SKTexture, MDLTexture, MTLTexture, or GLKTextureInfo)

• A SpriteKit scene (SKScene)

• A specially formatted image or array of six images, specifying the faces of a cube map

这是我修改后的代码:

private func handleFoundImage(_ imageAnchor: ARImageAnchor, _ node: SCNNode) {
    let name = imageAnchor.referenceImage.name!
    print("you found a \(name) image")
    
    let size = imageAnchor.referenceImage.physicalSize
    
    let skScene = SKScene(size: size)
    print("SKSCENE FRAME: \(skScene.frame)")
    skScene.backgroundColor = .white
    
    let skShape = SKShapeNode(rectOf: size, cornerRadius: 5.0)
    skShape.fillColor = .blue
    skShape.strokeColor = .red
    skShape.lineWidth = 1.5
    
    skScene.addChild(skShape)
    
    let plane = SCNPlane(width: size.width, height: size.height)
    
    let material = SCNMaterial()
    material.lightingModel = SCNMaterial.LightingModel.constant
    material.isDoubleSided = true
    material.diffuse.contents = skScene
    plane.materials = [material]
    
    let rectNode = SCNNode(geometry: plane)
    rectNode.eulerAngles.x = -.pi / 2
    node.addChildNode(rectNode)
}

当我在我的 iPhone 上运行它并将其指向图像时，应用程序崩溃，我得到以下堆栈跟踪。

2019-04-15 22:32:28.650432-0600 ImageTracker[3807:1577260] [DYMTLInitPlatform] platform initialization successful
2019-04-15 22:32:29.238671-0600 ImageTracker[3807:1577061] [Accessibility] ****************** Loading GAX Client Bundle ****************
2019-04-15 22:32:29.362407-0600 ImageTracker[3807:1577061] Metal GPU Frame Capture Enabled
2019-04-15 22:32:29.364368-0600 ImageTracker[3807:1577061] Metal API Validation Enabled
2019-04-15 22:32:29.499256-0600 ImageTracker[3807:1577061] [MC] System group container for systemgroup.com.apple.configurationprofiles path is /private/var/containers/Shared/SystemGroup/systemgroup.com.apple.configurationprofiles
2019-04-15 22:32:29.500912-0600 ImageTracker[3807:1577061] [MC] Reading from public effective user settings.
Point the camera at a dinsoaur.
you found a stegosaurus image
SKSCENE FRAME: (-0.0, -0.0, 0.10541000217199326, 0.06538714197231457)
<SKScene> name:'(null)' frame:{{-0, -0}, {0.10541000217199326, 0.065387141972314572}} anchor:{0, 0}
2019-04-15 22:32:37.189388-0600 ImageTracker[3807:1577292] validateTextureDimensions, line 1071: error 'MTLTextureDescriptor has width of zero.'
validateTextureDimensions:1071: failed assertion `MTLTextureDescriptor has width of zero.'

我不太确定什么是 MTLTextureDescriptor 或如何使宽度成为非零值。

有人可以帮我弄清楚我在这里做错了什么，或者这是正确的方法吗？同样，我只想找到一张图片，然后用 SKShapeNode 覆盖它。如果我必须使用一个很好的 SKScene 来执行此操作，我只需要帮助弄清楚如何执行此操作。如果这不是最好的方法，有人可以指点我可以找到仪表解决方案的文档吗？

谢谢!

Answer 1

那是因为这里 let size = imageAnchor.referenceImage.physicalSize 中 size 的宽度和高度为零。

您获得的尺寸将是您为引用图像设置的 physicalSize，肯定小于 1 米。因此，当您将其用作 skScene 的大小时，您创建的它的高度和宽度都为零。

例如:如果您的引用图片的物理尺寸为 10x15 厘米，则您的尺寸 的宽度为 0.1，高度为 0.15，这将更改为零。

我推荐:

let physicalSize = imageAnchor.referenceImage.physicalSize
let size = CGSize(width: physicalSize.width * 1000, height: physicalSize.height * 1000)