call one button at time

Create a boolean var - say, pressed - in the script assigned to the button to indicate if it's pressed. When the character is touching or clicking (or doing whatever it has to do to press the button) the button, check the variable pressed. If it's true, do nothing or play some sound to indicate it's already pressed. If pressed is false, assign true to it and do something to indicate the button is pressed - reduce the length of the button, or move it like it was pressed, or change its color etc:

 var pressed:boolean = false;
 
 // in the "button pressing" function check the var pressed:
 
   if (pressed){
     // do something to indicate it's already pressed
     audio.PlayOnShot(alreadyPressedSound);         .
   } else {
     pressed = true;
     audio.PlayOneShot(clickButtonSound); // play a click sound here, if any
     // do some modification in the button color or position
     // to indicate it was pressed
     .
   }
 

 

Thanks adonaletto, but in this case, I can press the button again, right? I need to know how to prevent that´s happens. How to stop the player to press the same button again?

I create this script but not work:

 var bt1 = false;
 var bt2 = false;
 var bt3 = false;

     if (hit.gameObject.tag == "button") {
         if (bt1 == true)
         return;
         else
     number ++;
     bt1 = true;
     var lobjetct : GameObject = GameObject.FindWithTag("machine");
     lobject.animation.Play ("anim1");

Tried this too:

    var bt1 = false;
 var bt2 = false;
 var bt3 = false;

     if (hit.gameObject.tag == "button" && bt1 == false) {
     number ++;
     bt1 = true;
     var lobjetct : GameObject = GameObject.FindWithTag("machine");
     lobject.animation.Play ("anim1");