使用RealityKit跟踪相机位置 [英] Track camera position with RealityKit

问题描述

如何使用RealityKit跟踪摄像机的位置?几个示例都在使用SceneKit，但我发现没有一个在使用RealityKit.我需要一个功能，例如:

How can you track the position of the camera using RealityKit? Several examples are using SceneKit, but I found none using RealityKit. I need a function such as:

func session(_ session: ARSession, didUpdate frame: ARFrame) {
    // Do something with the new transform
    let currentTransform = frame.camera.transform
    doSomething(with: currentTransform)
}

推荐答案

使用ARView Camera Transform:

您可以使用以下方法访问ARView Camera Transform:

You can access the ARView Camera Transform using the following method:

var cameraTransform: Transform

当前活动摄像机的变换.

The transform of the currently active camera.

因此，假设您的ARView被称为arView，您可以像这样访问Transform:

So assuming your ARView was called arView you could access the Transform like so:

let cameraTransform = arView.cameraTransform

但是，更有用的实现方式是使您的ARView通过使用以下内容来观察SceneEvents.Update:

A more useful implementation however would be to enable your ARView to observe SceneEvents.Updateby making use of the following:

subscribe(to:on:_:)

func subscribe<E>(to event: E.Type, on sourceObject: EventSource? = nil, _ handler: @escaping (E) -> Void) -> Cancellable where E : Event

这意味着您将拥有以下任何一个的观察者:

Which means you would have an observer of any:

事件每帧间隔触发一次，可用于执行 每帧的自定义逻辑.

event triggered once per frame interval that you can use to execute custom logic for each frame.

为此，您将: 首先导入Combine框架.

To do that you would: Firstly import the Combine Framework.

然后您将创建一个Cancellable变量:

You would then create a Cancellable variable:

var sceneObserver: Cancellable!

然后在ViewDidLoad中添加如下内容:

Then in ViewDidLoad add something like the following:

sceneObserver = arView.scene.subscribe(to: SceneEvents.Update.self) { [unowned self] in self.updateScene(on: $0) }

因此，每次更新都将调用以下内容:

Whereby each update calls the following:

/// Callback For ARView Update Events
/// - Parameter event: SceneEvents.Update
func updateScene(on event: SceneEvents.Update) {

  print(arView.cameraTransform)

}

使用ARSessionDelegate:

或者，您也可以通过订阅ARSessionDelegate例如在RealityKit中访问ARCamera:

Alternatively you can access the ARCamera from within RealityKit by subscribing to the ARSessionDelegate e.g:

arView.session.delegate = self

然后注册以下回调:

func session(_ session: ARSession, didUpdate frame: ARFrame)

一个有效的示例看起来像这样:

Whereby a working example would look something like this:

extension ViewController: ARSessionDelegate {

  func session(_ session: ARSession, didUpdate frame: ARFrame) {

    guard let arCamera = session.currentFrame?.camera else { return }
    print("""
      ARCamera Transform = \(arCamera.transform)
      ARCamera ProjectionMatrix = \(arCamera.projectionMatrix)
      ARCamera EulerAngles = \(arCamera.eulerAngles)
      """)

  }

}

希望它会为您指明正确的方向.

Hope it points you in the right direction.

这篇关于使用RealityKit跟踪相机位置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！