VRInteraction.cs

using UnityEngine;
using System.Collections;

public class Main : MonoBehaviour {
    //Constants
    protected const float GAZE_LENGTH       = 100;
    protected const float MAX_GAZE_DURATION = 2f;

    //Data
    protected GameObject    mObject;
    protected float         mGazeTime;

    void Start () {
        //Initialize
        mObject     = null;
        mGazeTime   = 0;
    }

    void Update () {
        //Raycast from eye/camera, check if it hit something
        RaycastHit hit;
        if (Physics.Raycast(new Ray(transform.position, transform.forward), out hit, GAZE_LENGTH)) {
            //If there's an object that was seen in the previous frame
            if (mObject != null) {
                //If the same as current object
                if (mObject == hit.collider.gameObject) {
                    //Increase gaze time
                    mGazeTime += Time.deltaTime;
                    if (mGazeTime > MAX_GAZE_DURATION) mGazeTime = MAX_GAZE_DURATION;

                    //Recolor
                    float color = (MAX_GAZE_DURATION - mGazeTime) / MAX_GAZE_DURATION;
                    ColorObject(mObject, new Color(1f, color, color));
                } else {
                    //Reset old object since it's different
                    ColorObject(mObject, Color.white);
                    mGazeTime = 0;
                }
            }

            //Save the object to variable
            mObject = hit.collider.gameObject;

            //If object exists and mouse is clicked
            if (mObject != null && Input.GetMouseButtonUp(0)) {
                //Move object elsewhere
                mObject.transform.position = new Vector3(Random.Range(-8, 8f), Random.Range(-2f, 2f), Random.Range(0, 3f));
            }
        } else {
            //If there was an object
            if (mObject != null) {
                //Reset
                ColorObject(mObject, Color.white);
                mGazeTime = 0;
            }

            //No object was seen
            mObject = null;
        }
    }

    protected void ColorObject(GameObject gameObject, Color color) {
        //Skip if no object
        if (gameObject == null) return;

        //Set material color
        Renderer objectRenderer = gameObject.GetComponent<Renderer>();
        if (objectRenderer != null) objectRenderer.material.color = color;
    }
}