Drag GameObject with mouse

Questions & Answers
1

I have maybe a dumb question, but how do I drag a GameObject when I click the mouse?

I'd like to use OnMouseDrag. When the user clicks on my GameObject it first does some animation (moves forward a bit). When the user still holds down the mouse button and moves the mouse, I'd like to have the GameObject move with it (with dampening).

Tried some stuff out but I can't get it to work.

Does anyone know how to do this? It would be of great help!

Thanks.

8

Drop this onto a gameobject, use the collider that matches your type of gameobject

using UnityEngine;
using System.Collections;

[RequireComponent(typeof(MeshCollider))]

public class GizmosController : 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));

}

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

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

}

}
4

There is a script which comes with Standard Assets of Unity called `DragRigidbody.js`. You can play with it by following these steps:

  • Create an empty `Scene` with a `Terrain`
  • Add some `GameObject` like `Cube` and `Sphere`
  • Assign `Rigidbody` to the ones that you want to be able to Drag (`Component` > `Physics` > `Rigidbody`)
  • Add a `First Person Controller` from the Prefabs of Standard Assets
  • Finally drag the `DragRigidbody.js` on the `First Person Controller` object in your scene.
  • Press the `Play` button and you are good to go

I don't know in how much into details you want to go, but in general the `DragRigidbody.js` script is using a combination of `Raycast`, `Rigidbody` and `SpringJoint` to achieve the Drag and Drop.

You can also check the Room of Shadows example which is a little bit more complicated but this is because they also highlighting the objects and playing with lights/shadows.

Have fun and good luck.

11

A little simpler

3D Drag:

void OnMouseDrag()
	{
		float distance_to_screen = Camera.main.WorldToScreenPoint(gameObject.transform.position).z;
		transform.position = Camera.main.ScreenToWorldPoint(new Vector3(Input.mousePosition.x, Input.mousePosition.y, distance_to_screen ));
	 
	}

Plane Drag:

   void OnMouseDrag()
    	{
    		float distance_to_screen = Camera.main.WorldToScreenPoint(gameObject.transform.position).z;
    		Vector3 pos_move = Camera.main.ScreenToWorldPoint(new Vector3(Input.mousePosition.x, Input.mousePosition.y, distance_to_screen ));
            transform.position = new Vector3( pos_move.x, transform.position.y, pos_move.z );
    	 
    	}
5

Thanks for your reactions. This is what I did to make it work:

void OnMouseDown()
{
    screenPoint = Camera.main.WorldToScreenPoint(scanPos);

    offset = scanPos - Camera.main.ScreenToWorldPoint(
        new Vector3(Input.mousePosition.x, Input.mousePosition.y, screenPoint.z));
}

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

    Vector3 curPosition = Camera.main.ScreenToWorldPoint(curScreenPoint) + offset;
    transform.position = curPosition;
}
2

Check out the script "DragRigidbodyShadow.js" from the Unity Shadow Demo Project: http://unity3d.com/support/resources/example-projects/shadowdemo

6

Sorry....what's "scanPos" of the code?

3

there is another script in unity's procedural example project.

7

"Sorry....what's "scanPos" of the code?"

scanPos is a the position (Vector3) of the gameobject you want to drag. In my case it is a scanner so scanPos stands for scanner position :-)

9

This is the simpliest way i can think of:

public class DragMove : MonoBehaviour
{
	void OnMouseDrag()
	{
		Vector3 point = Camera.main.ScreenToWorldPoint(new Vector3(Input.mousePosition.x,Input.mousePosition.y,(transform.position.z-Camera.main.transform.position.z)));
		point.z = transform.position.z;
		transform.position = point;
	}
}
10

the code on the previous page, it is moving the object from the angle of camera, I need the version which moves the object in respect to planes, from cameras angle [ for example from the cameras angle if i move the object it moves on the direction of y, but i want it to move on the direction of x , or z because its my plane, alltough the object moves on x, and partial y and partial z because of my camera angle how can i block it from moving on y direction and make it move on z only?

12

Simpler with Unity’s new UI:

    public void OnDrag (PointerEventData eventData)
    {
        Vector3 delta = eventData.pointerPressRaycast.worldPosition - eventData.pointerCurrentRaycast.worldPosition;
        delta.z = 0; // this is to keep the camera's Z fixed, change at will
        m_camera.transform.position += delta;
        CheckLimits();
    }

Make sure you add the IBeginDragHandler, IDragHandler, IEndDragHandler interfaces to your MonoBehaviour.