Best way to "highlight" an object on mouse over

[system]

Lets say I have like 25 different objects in the scene which are always visible for the camera with quite complex colliders. I then want to highlight whatever object I’m hovering over (with the mouse) by changing the texture or whatever.

Which is the best way to do this?

I guess I could send out raycasts every frame and change the texture whenever it hits something, but that seems quite expensive? Is there any other way?

[raoz]

This will be attached to all the things that can be highlighted with hovering.

Color startcolor;

void OnMouseEnter ()
{
    startcolor = renderer.material.color;
    renderer.material.color = Color.yellow;
}

void OnMouseExit ()
{
    renderer.material.color = startcolor;
}

[astracat111]

Okay so your problem with OnMouseEnter and _Exit is that you are setting yourself up to be confused if you are porting to a VR platform, or a platform that has a pointer controller. If you want to keep your project open ended and not only have it releasable for PC, you can do something like below:

Create a main game object that doesn’t get destroyed so that you have a scene manager object between scenes. Make a main game script, we will pretend it’s called MainGameScript.cs and it’s class name is MainGameScript and put this inside of it, above it’s class:

[System.Serializable]
public class MainInput_Ray
{
	public Ray ray = new Ray ();
	public RaycastHit hit;
	public bool hittingSomething { get; set; }
}

Then goes in your main game script’s start:

public MG_Ray mainInput_Ray;

void Start ()
{
    mainInput_Ray = new MainInput_Ray();
}

…and then this goes in your main game script’s update AFTER the scene is fully loaded and playing:

void Update ()
{ 
    mainInput_Ray.ray = MG_Camera.GetComponent<Camera> ().ScreenPointToRay (Input.mousePosition);
    mainInput_Ray.hittingSomething = Physics.Raycast (mainInput_Ray.ray, out mainInput_Ray.hit, 1000);
}

Now in your object’s script you can go like:

private MainGameScript mainGameScript;

void Start ()
{
    mainGameScript = GameObject.Find("MainGameScript"); //gameobject find is okay if it's in your start method
   //make sure you set your main game script's script execution order to FIRST
}

void Update()
{
    if (mainGameScript.mainInput_Ray.hittingSomething && (mainGameScript.mainInput_Ray.hit.transform == this.transform.parent.transform)) {
   }
}

Then throughout your entire project whenever you need to check if something is hit you do mainInput_Ray.hittingSomething == true???, check the results, throw an && in the if statement, just make sure the scene if fully loaded. Personally I have a state machine in my main game object that handles the loading screen, saving and loading of data and has a ‘SceneActive’ state I check against first.

Now if you have a VR controller you just have to replace this part:

mainInput_Ray.ray = MG_Camera.GetComponent<Camera>().ScreenPointToRay(Input.mousePosition);

This code is optimized just like OnMouseEnter, because you aren’t creating a new ray all together each and every frame, there is only one global ray you check against.

[Chaolice]

I’m updating the answer since a lot of links trace to this post despite it being depreciated.

Color _startcolor;
[SerializeField] Renderer _renderer;

void OnMouseEnter ()
{
    _startcolor = _renderer.material.color;
    _renderer.material.color = Color.red;
}

void OnMouseExit ()
{
    _renderer.material.color = _startcolor;
}

[dana-schmale]

Hey! I know this thread is pretty old, but it gave me the jumpstart I needed to get my colour change script working. I am VERY new to C#, so please let me know if this seems like a bad way of doing it.

Essentially I was able to get the OnMouseOver portion to work from the other replies, but not the OnMouseExit – the colour wouldn’t return to the startColour. I found that getting the startColour in Start fixed this. See below:

public class Highlight : MonoBehaviour
{
    private Color startColour;

    private void Start()
    {
        startColour = GetComponent<Renderer>().material.color; 
    }
    private void OnMouseOver()
    {
        GetComponent<Renderer>().material.color = new Color(1, 0, 0, 1);
    }

    private void OnMouseExit()
    {
        GetComponent<Renderer>().material.color = startColour;
    }
}