Simple drag and drop - no physics

Questions & Answers
1

I want to simply drag and drop objects without rigidbody or physics. I found a old script of this written in C#. Its not working for me - I get a “NullReferenceException”

Can somebody fix this or convert it into Javascript? Here the code:

using UnityEngine;

using System.Collections;

[RequireComponent(typeof(BoxCollider))]

public class MovePoint2 : MonoBehaviour
{
	private Vector3 screenPoint;
	private Vector3 offset;

	void OnMouseDown() 
	{ 
		screenPoint = Camera.main.WorldToScreenPoint(gameObject.transform.position);

		offset = gameObject.transform.position - Camera.main.ScreenToWorldPoint(new Vector3(Input.mousePosition.x, Input.mousePosition.y, screenPoint.z));

		Screen.showCursor = false;
	}

	void OnMouseDrag() 
	{ 
		Vector3 curScreenPoint = new Vector3(Input.mousePosition.x, Input.mousePosition.y, screenPoint.z);

		Vector3 curPosition = Camera.main.ScreenToWorldPoint(curScreenPoint) + offset;

		transform.position = curPosition;

	}

	void OnMouseUp()
	{
		Screen.showCursor = true;
	}
}

Here the Error in detail: UnityEngine.Camera.WorldToScreenPoint (Vector3 position) (at C:/BuildAgent/work/842f9557127e852/Runtime/ExportGenerated/Editor/UnityEngineCamera.cs:225)
MovePoint2.OnMouseDown () (at Assets/Scripts/General Scripts/MovePoint2.cs:13)
UnityEngine.SendMouseEvents:DoSendMouseEvents()

3

Javascript:

private var screenPoint: Vector3;
private var offset: Vector3;
private var curScreenPoint : Vector3;
private var curPosition : Vector3;
    
function Start () {
}

function Update () {
}

function OnMouseDown () {
	screenPoint = Camera.main.WorldToScreenPoint(gameObject.transform.position);
	offset = gameObject.transform.position - Camera.main.ScreenToWorldPoint(new Vector3(Input.mousePosition.x, Input.mousePosition.y, screenPoint.z));
	Screen.showCursor = false;
	}
	
function OnMouseDrag() { 
    curScreenPoint = new Vector3(Input.mousePosition.x, Input.mousePosition.y, screenPoint.z);
	curPosition = Camera.main.ScreenToWorldPoint(curScreenPoint) + offset;
    transform.position = curPosition;
	}

function OnMouseUp(){
    Screen.showCursor = true;
    }

Tips welcome!

2

Open new scene, make cube, add this script to cube (make sure you name script “MovePoint2” since this is the name of the class).

4

What if there is a camera angle?. I want to move to object within the plane only,

5

Check this out, this one has shown drop and drop in unity only in few lines of code — http://aarlangdi.blogspot.com.au