Reality Composer默认锚点能否通过代码手动设置？如Hit Test锚定特定点

Absolutely! You totally can manually set anchors for your Reality Composer scenes using code—this is such a useful workflow when you want to place content based on user interactions like tap-to-place hit tests. Let me walk you through exactly how to do this:

1. Prep Your Reality Composer Scene #

First, make sure you’ve exported your scene from Reality Composer correctly. For code integration, export it as a .reality file (or just embed the .rcproject directly in your Xcode project—either works perfectly).

2. Perform a Hit Test to Get Your Target Point #

Use ARKit’s hit testing to find the real-world surface or point where you want to anchor your scene. Here’s a Swift example for handling a screen tap:

@objc func handleScreenTap(_ gesture: UITapGestureRecognizer) {
    guard let arView = gesture.view as? ARView else { return }
    let tapLocation = gesture.location(in: arView)
    
    // Run hit test to find valid surfaces (adjust types based on your use case)
    if let hitResult = arView.hitTest(tapLocation, types: [.existingPlaneUsingGeometry, .estimatedHorizontalPlane]).first {
        // Attach our scene to this hit result's anchor
        addRealityComposerScene(to: hitResult.anchor, in: arView)
    }
}

3. Load and Anchor the Scene Programmatically #

Once you have your hit test result, load the Reality Composer scene and attach it to your custom anchor. Here’s how to wire it up:

func addRealityComposerScene(to targetAnchor: ARAnchor, in arView: ARView) {
    // Load your scene (replace "MyCustomScene" with your actual scene name)
    guard let sceneAnchor = try? Entity.loadAnchor(named: "MyCustomScene") else {
        print("Oops—failed to load the Reality Composer scene!")
        return
    }
    
    // Update the scene's transform to match the hit test point
    sceneAnchor.transform = targetAnchor.transform
    
    // Add the scene's anchor to the AR session
    arView.session.add(anchor: sceneAnchor)
}

Quick Tips to Avoid Headaches #

• Override Default Anchors: When you build scenes in Reality Composer, those floor/wall/face anchors are just default templates. By loading the scene as an Entity and attaching it to your own ARAnchor, you’re completely overriding that default behavior.
• Reposition Anytime: If you need to move the scene later, just update the transform property of the sceneAnchor entity—super easy!
• Framework Compatibility: This works seamlessly with both ARKit and RealityKit, since Reality Composer is built to integrate with both.

内容的提问来源于stack exchange，提问作者Mostafa