OnTouch

Adapted from OnMouseDown by User:Caue.rego, this Javascript sends `OnMouse` equivalent messages based on touch devices taps.

Attach the script to the camera that is rendering the clickable (tappable) objects.

Add a layer argument to the Raycast call if you need to avoid unnecessary intersections.

This is only for objects with colliders, not for `GUIText` and `GUITexture`.

Instead of calling `OnMouse` events, we use `OnPointer` (suggested name) to emphasize how we should avoid `OnMouse` due to performance warnings. (Though I've got no idea if that's just a legacy warning).

OnTouch.js

// Allows "OnMouse()" events to work on the mobile devices.
// Attach this to the main camera.
 
#pragma strict
#pragma implicit
#pragma downcast
 
private var lastHitObject : GameObject;
 
function Update ()
{
  var hit : RaycastHit;
  for (var i = 0; i < Input.touchCount; ++i)
  {
    // Construct a ray from the current touch coordinates
    var ray = camera.ScreenPointToRay(Input.GetTouch(i).position);
    if ( Physics.Raycast(ray, hit) )
    {
      var hitObject = hit.transform.gameObject;
      if (Input.GetTouch(i).phase == TouchPhase.Began)
      {
        lastHitObject = hitObject;
        hitObject.SendMessage("OnPointerDown");
      }
      if (Input.GetTouch(i).phase == TouchPhase.Ended)
      {
        if (lastHitObject == hitObject)
        {
          hitObject.SendMessage("OnPointerUpAsButton");
        }
        hitObject.SendMessage("OnPointerUp");
        lastHitObject = null;
      }
    }
  }
}

Then, on whichever script you'd use OnMouse, use this instead:

// Usage instance
 
#if UNITY_EDITOR or UNITY_STANDALONE or UNITY_WEBPLAYER
function OnMouseUpAsButton () { OnPointerUpAsButton(); }
#endif
function OnPointerUpAsButton () {
  //whatever
}