Simulation/Assets/Scripts/UI/UIDragSpawner.cs

using UnityEngine;
using UnityEngine.UI;
using UnityEngine.EventSystems;

public class UIDragSpawner : MonoBehaviour, IBeginDragHandler, IDragHandler, IEndDragHandler
{
    public RectTransform rectTransform;
    public LayerMask mask;
    private GameObject dragPreview;
    public SimulationModel targetModel;
    Transform objectRoot;
    //private CanvasGroup canvasGroup;

    void Awake()
    {
        objectRoot = ObjectRoot.I.transform;
    }

    public void SetInfo(SimulationModel spawnTarget, Sprite thumbnail)
    {
        this.GetComponent<Image>().sprite = thumbnail;
        targetModel = spawnTarget;

    }

    public void OnBeginDrag(PointerEventData eventData)
    {
        dragPreview = Instantiate(targetModel).gameObject;
        dragPreview.transform.SetParent(objectRoot);
    }

    public void OnDrag(PointerEventData eventData)
    {
        if (dragPreview)
        {
            Ray ray = Camera.main.ScreenPointToRay(eventData.position);
            if (Physics.Raycast(ray, out RaycastHit hit, 100.0f, mask))
            {
                dragPreview.transform.position = hit.point; 
            } 
        }
    }

    public void OnEndDrag(PointerEventData eventData)
    {
        if (IsPointerOverScrollRect(rectTransform))
        {
            Destroy(dragPreview);
            dragPreview = null;
            return;
        }
        else
        {
            DataManager.I.AddModel(dragPreview.GetComponent<SimulationModel>());
        }
    } 
    public bool IsPointerOverScrollRect(RectTransform rt)
    {
        return RectTransformUtility.RectangleContainsScreenPoint(rt, Input.mousePosition);
    }
}