arfoundation-samples/Assets/Scenes/InputSystem/InputSystem_PlaceOnPlane.cs

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

namespace UnityEngine.XR.ARFoundation.Samples
{
    public class InputSystem_PlaceOnPlane : MonoBehaviour
    {

        [SerializeField]
        [Tooltip("Instantiates this prefab on a plane at the touch location.")]
        GameObject m_PlacedPrefab;

        /// <summary>
        /// The prefab to instantiate on touch.
        /// </summary>
        public GameObject placedPrefab
        {
            get { return m_PlacedPrefab; }
            set { m_PlacedPrefab = value; }
        }

        /// <summary>
        /// The object instantiated as a result of a successful raycast intersection with a plane.
        /// </summary>
        public GameObject spawnedObject { get; private set; }

        void Awake()
        {
            m_RaycastManager = GetComponent<ARRaycastManager>();
        }

        public void AddObject(InputAction.CallbackContext context)
        {
            var touchPosition = context.ReadValue<Vector2>();
            if (m_RaycastManager.Raycast(touchPosition, s_Hits, TrackableType.PlaneWithinPolygon))
            {
                // Raycast hits are sorted by distance, so the first one
                // will be the closest hit.
                var hitPose = s_Hits[0].pose;

                if (spawnedObject == null)
                {
                    spawnedObject = Instantiate(m_PlacedPrefab, hitPose.position, hitPose.rotation);
                }
                else
                {
                    spawnedObject.transform.position = hitPose.position;
                }
            }
        }

        static List<ARRaycastHit> s_Hits = new List<ARRaycastHit>();

        ARRaycastManager m_RaycastManager;
    }

}