Decouple controller logic from Unity3D GUI controls using C#, like fade OnGUI - unity3d

Question

I'm failing to understand how to decouple business logic of a controller and view for Unity3D GUI controls.
For example, if I have a GUI.Box, how would I implement a controller to fade in or out from the OnGUI lifecycle stage of the view?
View
using UnityEngine;
public class ExampleView : MonoBehaviour {
protected void OnGUI () {
GUI.Box(new Rect(0, 0, 100, 100), "Title");
}
}
If I instantiate a controller to change alpha of GUI.color it would need notification of Update() from the main view thread.
To roughly encapsulate functionality, if this were a single script it could be implemented as:
using UnityEngine;
public class ExampleView : MonoBehaviour {
private Color color;
protected void Start () {
color = Color.white;
}
protected void OnGUI () {
GUI.color = color;
GUI.Box(new Rect(0, 0, 100, 100), "Title");
}
protected void Update () {
if(color.a > 0)
color.a -= Time.deltaTime / 3;
}
}
Akin to how iTween animates changes to properties using iTween.fadeTo(gameObject, ... how can this be implemented for Unity3d GUI controls using statements like FadeOut()?
There's probably no way to target individual GUI controls unless multiple controller instances are specified OnGUI(). However, it would be cool to control isolated GUI instances such as fading in a GUI.Box followed by GUI.Label.

Answer 1

Are you looking for something like this?:
using UnityEngine;
public class ExampleView : MonoBehaviour {
private Color color;
private bool bFadeIn = false;
private bool bFadeOut = false;
protected void Start () {
color = Color.white;
}
public void FadeOut(){
bFadeOut = true;
bFadeIn = false;
}
public void FadeIn(){
bFadeIn = true;
bFadeOut = false;
}
protected void OnGUI () {
GUI.color = color;
GUI.Box(new Rect(0, 0, 100, 100), "Title");
}
protected void Update () {
if(bFadeOut && color.a > 0.0)color.a -= Time.deltaTime / 3;
if(bFadeIn && color.a < 1.0)color.a += Time.deltaTime / 3;
}
}
You might also want to include a flag to determine when the control is invisible and, if invisible, skip the full GuiRender function.

Answer 2

Dont know if this is what you are looking for, but its a simple way to add fade effect to gui..
using UnityEngine;
using System.Collections;
/**Fade In/Out Instructions:
* 1.Create bool fadeIn. Create float alpha.
* 2.Call Fade() method at start of OnGUI().
* 3.Put 'GUI.color = new Color(1,1,1,alpha)' above the elements you want to fade'.
* 4.To fade in, fadeIn = true.
* 5.To fade out, fadeIn = false.
* 6.To deactivate buttons on fade out, wrap gui in 'if(alpha > 0)'
**/
public class MainMenuGUI : MonoBehaviour {
int buttonWidth;
int buttonHeight;
public float alpha;
public bool fadeIn;
// Use this for initialization
void Start () {
buttonWidth = 100;
buttonHeight = 50;
fadeIn = true;
}
void OnGUI(){
Fade();
GUI.color = new Color(1,1,1,alpha);
if(alpha > 0)
{
if (GUI.Button (new Rect ((Screen.width/2)-50, (Screen.height/2)-(buttonHeight*4/2), 100, 50), "PLAY"))
{
fadeIn = false;
Debug.Log("Play pressed");
}
if (GUI.Button (new Rect ((Screen.width/2)-50, ((Screen.height/2)-(buttonHeight*4/2)+ buttonHeight), 100, 50), "SCORES"))
{
Debug.Log("Scores pressed");
}
if (GUI.Button (new Rect ((Screen.width/2)-50, ((Screen.height/2)-(buttonHeight*4/2)+ buttonHeight*2), 100, 50), "OPTIONS"))
{
Debug.Log("Options pressed");
}
if (GUI.Button (new Rect ((Screen.width/2)-50, ((Screen.height/2)-(buttonHeight*4/2)+ buttonHeight*3), 100, 50), "EXIT"))
{
Debug.Log("Exit pressed");
}
}
}
void Fade(){
if(fadeIn){
alpha = Mathf.Clamp(alpha+0.01f,0,1);
}else{
alpha = Mathf.Clamp(alpha-0.01f,0,1);
}
}
}
Good luck on your game :)