Detect Collisions While Dragging 3D Game Object

Question

Hello i am making a game in which i have to drag a sphere on x axis and z axis on a plane with my mouse and i have created walls from cubes so that my sphere not go anywhere else in the game but while dragging my sphere is not detecting collisions with the wall i also added rigidbody but nothing is working ths is my code thanks

using UnityEngine;
using System.Collections;


public class Ball : MonoBehaviour
{
    Rigidbody r;
    private void Start()
    {

        r = GetComponent<Rigidbody>();

    }

    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);

    }

  }

Answer 1

This is an old thread, but maybe someone wants to do the same..

I found a nice way on the internet to do this:

This thread

https://forum.unity.com/threads/collision-detection-while-dragging-object.182493/

links to this video

https://www.youtube.com/watch?v=ZfjVR-0ZFHU

which explains a solution.

If you don't want to watch or read too much:

Basically you should stop setting the transform, because this cancels physics!

This is all you need:

private void Update()
{
    rb.velocity = (getWorldPosition() - transform.position) * followSpeed;
}

private Vector3 getWorldPosition()
{
    lastMousePos = Camera.main.ScreenToWorldPoint(Input.mousePosition);
    lastMousePos.z = 0;
    return lastMousePos - offset;
}

private void OnMouseDown()
{
    lastMousePos = Camera.main.ScreenToWorldPoint(Input.mousePosition);
    lastMousePos.z = 0;
    offset = lastMousePos - transform.localPosition;
}

Answer 2

Because you're using transform.position you're basically teleporting your object around, so it's possible it will be able to teleport into or through a wall without any problem.

You can still detect collisions using the OnCollision event, as this will be triggered when your object rematerialises, but the physics engine won't stop the objects intersecting.

If you want your movement to be limited by physics, you need to use something like either Rigidbody.MovePosition or Rigidbody.AddForce

Answer 3

As @JeffUK points out my mistake a have changed the code a bit

public class Ball : MonoBehaviour
{
    public float speed = 10f;
    Rigidbody r;
    private void Start()
    {
        r = GetComponent<Rigidbody>();
    }

    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));
        // here we are adding force on X and Z axis and i put normalized so the magnitude will be 1
        // It will prevent the super fast moving of the ball
        r.AddForce(new Vector3(pos_move.x, 0f, pos_move.z).normalized * speed * Time.deltaTime, ForceMode.VelocityChange);
    }

    private void OnMouseUp()
    {
        // it will stop moving the ball as soon as you lift the left mouse button up
        r.velocity = Vector3.zero;
        r.angularVelocity = Vector3.zero;
    }
}

I also add the float called speed, you can tweak its value to get your desired speed.

Now the only problem we have is the ball will not move to the mouse pointer, but it will gradually follow it.

And yes this time i have tested it myself. :)