Changing material of an object

Question

Hi. I looked for a solution to this but couldn't find anything. What i want to do is change the material of an object every few seconds. Here is my code:

     private float countdown;
     public float originalCountdown;
     public Material white, black;
     
     void Start () {
         countdown = originalCountdown;
     }
     
     void Update() {
         countdown -= Time.deltaTime;
         if (countdown <= 0) {
             Change ();
         }        
     }
 
     void Change() {
         countdown = originalCountdown;
         if (renderer.material = black) {
             Debug.Log ("White");
             renderer.material = white;
         } else if (renderer.material = white) {
             Debug.Log ("Black");
             renderer.material = black;
         }
     }
 }

What is happening now is that the material changes from black to white and i receive the message "White". Then the material stays white and i keep receiving the message "White" every time that Change() is called.

I really can't understand what is bad with the code. Also i am not using == because it only works with =. Not sure why.

Pretty new to all this anyway.

Answer 1

Best Answer

Answer by robertbu · Apr 27, 2014 at 11:42 PM

For comparison operations, you need to use double equals ('=='). In addition, since you are switching, you don't need the else:

  void Change() {
        countdown = originalCountdown;
        if (renderer.material == black) {
          Debug.Log ("White");
          renderer.material = white;
        } 
     else {
          Debug.Log ("Black");
          renderer.material = black;
        }

}

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Green123 · Apr 28, 2014 at 12:36 AM 0

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Now i receive the message "Black" and it never changes from black to white.

Green123 · Apr 28, 2014 at 12:41 AM 0

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It only changes when i use =, not ==.

robertbu · Apr 28, 2014 at 12:54 AM 0

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Single '=' is definitely not the right way to solve your issue. I'm guessing that something is changing the material instance which means the material, though black, will not evaluate to the material you assigned. You can use a boolean instead. At the top of the file:

 private bool isBlack = false;  // Set for original color.

Then the code changes to:

 void Change() {
        countdown = originalCountdown;
        if (isBlack) {
          Debug.Log ("White");
          renderer.material = white;
        } 
     else {
          Debug.Log ("Black");
          renderer.material = black;
        }
     isBlack = !isBlack;
 }

Green123 · Apr 28, 2014 at 01:42 AM 0

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Yeah it seems that works perfectly. Thanks a lot.

Changing material of an object

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