Unity component for placing a target gameobject on a plane. Raycasts from the center of the screen

ARPlanePlacement.cs

using System.Collections.Generic;
using UnityEngine;
using UnityEngine.XR.ARFoundation;
using UnityEngine.XR.ARSubsystems;

/// <summary>
/// Component for placing a target gameobject on a plane. Raycasts from the center of the screen.
/// </summary>
public class ARPlanePlacement : MonoBehaviour
{
    [SerializeField]
    [Tooltip("The target game object that we're trying to place")]
    private Transform target;

    [SerializeField]
    [Tooltip("Y Offset from the AR Plane. Useful for avoiding occlusion artifacts")]
    private float yOffset = 0.05f;

    [SerializeField]
    [Tooltip("ARRaycastManager. Usually attached to the AR Session Origin")]
    private ARRaycastManager raycastManager;

    [SerializeField]
    [Tooltip("ARPlaneManager. Usually attached to the AR Session Origin")]
    private ARPlaneManager planeManager;
    private List<ARRaycastHit> hits = new List<ARRaycastHit>();
    private Vector2 screenPos;
    private bool isPlacing = true;

    public void TogglePlacement()
    {
        isPlacing = !isPlacing;

        planeManager.enabled = isPlacing;
        foreach (var plane in planeManager.trackables)
        {
            plane.gameObject.SetActive(isPlacing);
        }
    }

    private void Start()
    {
        screenPos = new Vector2(Screen.width / 2f, Screen.height / 2f);
    }

    private void LateUpdate()
    {
        if (isPlacing && Raycast(out Pose pose))
        {
            pose.position.y += yOffset;
            target.SetPositionAndRotation(pose.position, pose.rotation);
        }
    }
    
    /// <summary>
    /// Perform a AR Raycast against an AR plane
    /// </summary>
    /// <param name="pose">Pose of the raycast hit, if successful</param>
    /// <returns>True if raycast succeeded</returns>
    private bool Raycast(out Pose pose)
    {
        if (raycastManager.Raycast(screenPos, hits))
        {
            foreach (ARRaycastHit hit in hits)
            {
                if ((hit.hitType & TrackableType.Planes) != 0)
                {
                    ARPlane plane = planeManager.GetPlane(hit.trackableId);
                    pose = hit.pose;
                    return true;
                }
            }
        }
        pose = Pose.identity;
        return false;
    }
}