KEEP INSTANTIATE PREFAB ONMOUSEDOWN

Question

Hi, I have been looking for the solution to keep a prefab dragging for a long time. If i drag a gameobject through a viewportPos, the gameobject will be destroyed and instantiate a prefab at mouse position. While my mouse still down, i would like to keep the prefab dragging. Is there solution for doing that??? here is my script:

  public void OnDrag(PointerEventData eventData)
 
     {
 
 
 
         Vector2 item_world_position = Camera.main.ScreenToWorldPoint(Input.mousePosition);
 
         transform.position = item_world_position;
 
         var viewportPos = Camera.main.WorldToViewportPoint(transform.position);
 
         if (viewportPos.y > 0.165) 
         {
             
                 // Get the prefab to instantiate
                 Transform itemprefab = itemBeingDragged.GetComponent<InventoryItem>().item_prefab;
 
                 // Instantiate it to world position
                 Instantiate(itemprefab, item_world_position, Quaternion.identity);
                 itemprefab.transform.SetParent(GameObject.FindGameObjectWithTag("GroundedItem").transform, true);
                 Destroy(itemBeingDragged);
                 Destroy(itemBeingDragged.transform.parent.gameObject);
             
         }
 
 
 
 
 
 
 
 
 
     }

Answer 1

It can be done this way.

Add the script [i will call it the First ] to the gameobject you drag through viewport.
Add a Spawned script to the object you want to spawn

Warning: You are destroying the First script after the new object is spawned. If you do that, it will not work. I will recommend you to disable it til you are holding the new Spawned object. Once you do the mouse up on the new Spawned object, then destroy First.

------------------EDIT--------------------------

So i made a sample project of this scenario, tested it and it works. I would recommend you also to make a simple sample project with one UI image object in the scene, and one UI image prefab which spawns. As i am not aware of all the details of the project requirements, once you get a hold of the concept, you can add your custom functionality.

First script.

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.EventSystems;
 using UnityEngine.UI;
 
 public class First : MonoBehaviour, IBeginDragHandler, IDragHandler, IEndDragHandler
 {
     public GameObject itemprefab;
     private Spawned _spawnedScript;
     public static GameObject itemBeingDragged;
 
     private Transform thisObjectTransform;
     private Transform spawnedItemParent;//parent of the spawned item
     private Transform mainCamTrans;
     private Camera mainCamScript;
     private Vector2 item_world_position;
     private Vector3 viewportPos;
 
     Vector3 startPosition;
     Transform startParent;
     PointerEventData data;
 
     void Start()
     {
         //caching for optimisation
         spawnedItemParent = GameObject.Find("Canvas").transform;//not recommended method. Must be cached from some manager script 
         mainCamScript = Camera.main;
         mainCamTrans = Camera.main.transform;
         thisObjectTransform = transform;
         item_world_position = Vector2.zero;
         viewportPos = Vector3.zero;
     }
 
 
     public void OnBeginDrag(PointerEventData beginData)
     {
         //pass the BEGIN pointer event data to the new spawnned object
         if (_spawnedScript != null)//null till the object is spawned
         {
             _spawnedScript.OnBeginDrag(beginData);
         }
 
         itemBeingDragged = gameObject;
 
         startPosition = thisObjectTransform.position;
         startParent = thisObjectTransform.parent;
     }
 
     public void OnDrag(PointerEventData duringData)
     {
         //pass the DRAG pointer event data to the new spawnned object
         if (_spawnedScript != null)
         {
             _spawnedScript.OnDrag(duringData);
         }
 
         item_world_position = mainCamScript.ScreenToViewportPoint(new Vector3(duringData.position.x , duringData.position.y , mainCamTrans.position.z));
 
         thisObjectTransform.position = item_world_position;
 
         viewportPos = mainCamScript.WorldToViewportPoint(thisObjectTransform.position);
 
         if (viewportPos.y > 0.165 && _spawnedScript==null)
         {
             GameObject go = Instantiate(itemprefab, spawnedItemParent);
 
             go.transform.position = item_world_position;
 
             _spawnedScript = go.GetComponent<Spawned>();
 
             /*
              * Sorry i forgot to warn you that disabling the FIRST script will disable the pointer system
              * I would recommend to make its color to "Clear" so that it is not visible.
              * We will disable/destroy it when the player performs mouse up
             */
             itemBeingDragged.GetComponent<Image>().color =  Color.clear;
         }
     }
 
     public void OnEndDrag(PointerEventData endData)
     {
         //pass the END pointer event data to the new spawnned object
         if (_spawnedScript != null)
         {
             _spawnedScript.OnEndDrag(endData);
             /*
              * Here we will disable/destroy this script.
              * Make sure that it is after we have passed on the pointer data
             */
 //            itemBeingDragged.SetActive(false);
             Debug.Log("First objtect destruction");
             Destroy(this.gameObject);
         }
 
         itemBeingDragged = null;
 
         if (thisObjectTransform.parent == startParent)
         {
             thisObjectTransform.position = startPosition;
         }
 
     }
 
 
 }

Spawned script.

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.EventSystems;
 
 //This is the new spawned object
 public class Spawned : MonoBehaviour, IBeginDragHandler, IDragHandler, IEndDragHandler
 {
     Vector2 temp;
 
     void Start()
     {
         temp = Vector2.zero;//cache for optimisation
     }
 
     public void OnBeginDrag(PointerEventData beginData)
     {
         //give the object the touch/mouse position
         //vector3 should not be used else it will give Z depth to the object
         temp =  Camera.main.ScreenToWorldPoint(beginData.position);
         transform.position = temp;
     }
 
     public void OnDrag(PointerEventData duringData)
     {
         //give the object the touch/mouse position
         //vector3 should not be used else it will give Z depth to the object
         temp =  Camera.main.ScreenToWorldPoint(duringData.position);
         transform.position = temp;
     }
 
     public void OnEndDrag(PointerEventData endData)
     {
         //give the object the touch/mouse position
         //vector3 should not be used else it will give Z depth to the object
         temp =  Camera.main.ScreenToWorldPoint(endData.position);
         transform.position = temp;
     }
 
 }

KEEP INSTANTIATE PREFAB ONMOUSEDOWN

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