How to fade in onGUI on trigger enter/exit? Gui shows on trigger, but no fade.

Question

Have this script from a YT tutorial by SpeedTutor:

 #pragma strict
 
 private var guiShow : boolean = false;
 
 var fadeColor : Texture;
 
 function OnTriggerStay (Col : Collider)
 {
     if(Col.tag == "Player")
     {
         guiShow = true;
     }
 }
 
 function OnTriggerExit (Col : Collider)
 {
     if(Col.tag == "Player")
     {
         guiShow = false;
     }
 }
 
 function OnGUI()
 {
     if(guiShow == true)
     {
         GUI.DrawTexture(Rect(Screen.width / 1000.0, Screen.height / 1000.0, 2048, 1024), fadeColor);
     }
 }

Pops a gui texture from enter until exit. Would like to fade texture "in" on enter, then "out" on exit. For instance, during a respawn or as a "flash" effect. I'm a scrub at code and have only recently started playing around with scripting, my knowledge of syntax, order and structure is very poor. If someone could help me out as to which function to put where in order to acheive the desired effect, that would be splendid.

TIA

Answer 1

GUI.color sets the global tinting for the GUI. It's an (r,g,b,a) value, where a is the alpha (transparency). If you set it to something less than one, the GUI will be semi-transparent.

To fade in or out, you need to gradually change the alpha value. You can use coroutines to do this, as in the code below. The FadeIn() and FadeOut() coroutines fade over 1 second. I made them short to keep the example clear. In practice, you'll probably want to modify the coroutines to update the alpha value every frame and use a variable to specify the fade duration. The Coroutines manual page has an example that does this.

 private var guiShow : boolean = false;
  
 var fadeColor : Texture;
 var currentGUIColor : Color;
  
 function OnTriggerStay (Col : Collider) 
 {
     if ((Col.tag == "Player") && !guiShow)
     {
         FadeIn();
     }
 }
  
 function OnTriggerExit (Col : Collider)
 {
     if ((Col.tag == "Player") && guiShow)
     {
         FadeOut();
     }
 }
  
 function OnGUI()
 {
     if (guiShow)
     {
         var originalColor = GUI.color;
         GUI.color = currentGUIColor;
         GUI.DrawTexture(Rect(Screen.width / 1000.0, Screen.height / 1000.0, 2048, 1024), fadeColor);
         GUI.color = originalColor;
     }
 }
 
 function FadeIn()
 {
     guiShow = true;
     for (var i = 0; i < 10; i++) 
     {
         currentGUIColor = new Color(1,1,1, i/10);
         yield WaitForSeconds(0.1f);
     }
     currentGUIColor = new Color(1,1,1,1);
 }
 
 function FadeOut()
 {
     for (var i = 10; i > 10; i--) 
     {
         currentGUIColor = new Color(1,1,1, i/10);
         yield WaitForSeconds(0.1f);
     }
     currentGUIColor = new Color(1,1,1,0);
     guiShow = false;
 }

[1]: http://docs.unity3d.com/Documentation/Manual/Coroutines.html

How to fade in onGUI on trigger enter/exit? Gui shows on trigger, but no fade.

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