Code part to attach an anchor to a plane in AR Foundation

ARPlaceHologram.cs

ARAnchor CreateAnchor(in ARRaycastHit hit)
{
    ARAnchor anchor;

    // ... here, we'll place the plane anchoring code!

    // If we hit a plane, try to "attach" the anchor to the plane
    if (hit.trackable is ARPlane plane)
    {
        var planeManager = GetComponent<ARPlaneManager>();
        if (planeManager)
        {
            var oldPrefab = _anchorManager.anchorPrefab;
            _anchorManager.anchorPrefab = _prefabToPlace;
            anchor = _anchorManager.AttachAnchor(plane, hit.pose);
            _anchorManager.anchorPrefab = oldPrefab;
            
            Debug.Log($"Created anchor attachment for plane (id: {anchor.nativePtr}).");
            return anchor;
        }
    }

    // Otherwise, just create a regular anchor at the hit pose
    // (see previous code snippet)
    // ...