Changing and resetting materials dynamically?

Questions & Answers
1

Hi

I want to apply a given material to any object being directly looked at, and then have it reset back to it's original material when it is no longer being directly looked at.

I can handle the change to new material OK by doing a Physics.Raycast forward from the player camera, and setting rayHit.transform.renderer.material.

The problem is in reverting back to the original material. I have hundreds of game objects using any one of 10 materials. Obviously I want to avoid having to keep arrays of these objects to check they're no longer being looked at.

Is there a way to somehow know what just the penultimate object looked at was, so I only have to revert that single object's material?

Thanks

3 
using UnityEngine;

public class MaterialEyes : MonoBehaviour {

[SerializeField] Material material;

[HideInInspector] [SerializeField] new Camera camera;
[HideInInspector] [SerializeField] Vector3 screenCenter;

void Reset () {
    camera = GetComponent<Camera>();
    screenCenter = new Vector3(.5F, .5F, 0);
}

class ChangedObject {
    public Renderer renderer;
    public Material originalMaterial;

    public ChangedObject (Renderer renderer, Material material) {
        this.renderer = renderer;
        originalMaterial = renderer.sharedMaterial;
        renderer.material = material;
    }
}

ChangedObject changedObject;
RaycastHit raycastHit;
void Update () {
    Ray ray = camera.ViewportPointToRay(screenCenter);
    if (Physics.Raycast(ray, out raycastHit)) {
        Renderer hitRenderer = raycastHit.transform.renderer;
        if (hitRenderer) {
            if (changedObject != null)
                if (changedObject.renderer == hitRenderer) return;
                else changedObject.renderer.material = changedObject.originalMaterial;
            changedObject = new ChangedObject(hitRenderer, material);
        }
    } 
    else if (changedObject != null) {
        changedObject.renderer.material = changedObject.originalMaterial;
        changedObject = null;
    }
}

}
2

Before you change the material, have a GameObject variable and Material variable set up to "capture" the material and game object you hit with a ray before you do anything else to it. Then when you leave it, you can tell the game object to revert back to the stored material value.

4

This is Jessy's C# code changed to Javascript. (No advantage, I just needed to integrate it within an existing .js)

To recap, attach this script to a camera and it will temporarily change the material of the object you're looking at (in the centre of screen) to the one you assign to newMaterial

(Thanks again Jessy, as a C# newbie I learned a lot from studying your code) 

var newMaterial : Material;
private var screenCenter : Vector3; 
private var raycastHit : RaycastHit; 
private var theRenderer : Renderer;
private  var originalMaterial : Material;

function Start () {
    screenCenter =  Vector3(.5F, .5F, 0);
}
function Update () {
    var ray : Ray = camera.ViewportPointToRay(screenCenter);  // creates a ray going from camera to viewport center
    if (Physics.Raycast(ray, raycastHit)) {     // get what that ray hits
        var hitRenderer : Renderer = raycastHit.transform.renderer; //get the renderer of the hit object
        if (hitRenderer) {
            if (theRenderer != null){ //if we've already assigned a renderer
                if (theRenderer == hitRenderer) return; //if this the same renderer do nothing
                else theRenderer.material = originalMaterial; // if it's a different one, put the original material back
            }
            theRenderer = hitRenderer;
            originalMaterial = hitRenderer.sharedMaterial;
            hitRenderer.material = newMaterial;
        }
    } 
    else if (theRenderer != null) { // if we didn't hit anything and there exists a changed renderer, put the original material back
        theRenderer.material = originalMaterial;
        theRenderer = null;
    }   
}