Click to Move System in Unity

Let’s write a simple script that will move an object to a clicked location like this:

Here’s the script that gets added to the player object:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class ClickToMove : MonoBehaviour
{
    // Variable to store the speed at which the object should move
    public float speed = 10f;
    // Variable to store the target destination
    public Vector3 _targetDestination;
    
    // Start is called before the first frame update
    void Start()
    {
        // Set the target destination to the object's starting position
        _targetDestination = transform.position;
    }

    // Update is called once per frame
    void Update()
    {
        // Check if the left mouse button was clicked
        if (Input.GetMouseButtonDown(0))
        {
            // Create a ray from the main camera to the mouse position
            Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
            RaycastHit hit;
            // Check if the ray hits an object on the "Floor" layer
            if (Physics.Raycast(ray, out hit, 1000f, LayerMask.GetMask("Floor")))
            {
                // Set the target destination to the point where the ray hit the object
                Vector3 target = hit.point;
                // Set the y-position of the target to the object's current y-position
                // This is to prevent the object from changing height when moving
                target.y = transform.position.y;
                _targetDestination = target;
                // Rotate the object to face the target destination
                transform.LookAt(target);
            }
        }
        // Check if the distance between the object and the target destination is greater than 0.1
        if (Vector3.Distance(transform.position, _targetDestination) > 0.1f)
        {
            // If so, move the object towards the target destination
            MoveThePlayer();
        }
    }

    // Method to move the object towards the target destination
    void MoveThePlayer()
    {
        // Move the object towards the target destination at a speed of "speed" per second
        transform.position = Vector3.MoveTowards(transform.position, _targetDestination, speed * Time.deltaTime);
    }

}

Now our player will go wherever we click.

Just for fun, let’s do some optimization:

1. Instead of using Physics.Raycast in the Update function, we could use a separate function to handle the raycasting and mouse input. This would reduce the number of calls to Physics.Raycast and make the code easier to read.
2. Instead of checking the distance between the object and the target destination every frame, we could use a boolean variable to track whether the object has reached the target destination. This would prevent unnecessary calls to Vector3.Distance.
3. We could also use a coroutine to move the object towards the target destination instead of using MoveThePlayer in the Update function. This would allow us to control the speed at which the object moves more accurately.

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class ClickToMove : MonoBehaviour
{
    // Variable to store the speed at which the object should move
    public float speed = 10f;
    // Variable to store the target destination
    public Vector3 _targetDestination;
    // Variable to track whether the object has reached the target destination
    private bool _hasReachedDestination;
    
    // Start is called before the first frame update
    void Start()
    {
        // Set the target destination to the object's starting position
        _targetDestination = transform.position;
    }

    // Update is called once per frame
    void Update()
    {
        // Call the HandleInput function
        HandleInput();
        // Check if the object has reached the target destination
        if (!_hasReachedDestination)
        {
            // If not, move the object towards the target destination
            MoveThePlayer();
        }
    }

    // Method to move the object towards the target destination
    void MoveThePlayer()
    {
        // Move the object towards the target destination at a speed of "speed" per second
        transform.position = Vector3.MoveTowards(transform.position, _targetDestination, speed * Time.deltaTime);
        // Check if the object has reached the target destination
        if (Vector3.Distance(transform.position, _targetDestination) <= 0.1f)
        {
            // If so, set _hasReachedDestination to true
            _hasReachedDestination = true;
        }
    }

    // Function to handle mouse input and raycasting
    void HandleInput()
    {
        // Check if the left mouse button was clicked
        if (Input.GetMouseButtonDown(0))
        {
            // Create a ray from the main camera to the mouse position
            Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
            RaycastHit hit;
            // Check if the ray hits an object on the "Floor" layer
            if (Physics.Raycast(ray, out hit, 1000f, LayerMask.GetMask("Floor")))
            {
                // Set the target destination to the point where the ray hit the object
                Vector3 target = hit.point;
                // Set the y-position of the target to the object's current y-position
                // This is to prevent the object from changing height when moving
                target.y = transform.position.y;
                _targetDestination = target;
                // Rotate the object to face the target destination
                transform.LookAt(target);
                // Set _hasReachedDestination to false
                _hasReachedDestination = false;
            }
        }
    }
}

Ah, that’s better!