Why is tapping Android Screen detected via Mouse Button 0 calls

Questions & Answers
1

Hey guys, quick Android question.

If I have the target platform switched to Android and have the following code (and nothing else) in the scene running:

	void Update () {
	
		if ( Input.GetMouseButtonDown (0) ) {
			Debug.Log ("Button Pressed");
		}
	}

If I tap the Android screen (while using Unity Remote), the message gets displayed. This is also the case if ‘mouse 0’ is an input within an InputManager axis and I touch the screen (obviously asking if that axis has been pressed).

Is there a reason that tapping the screen is identified with pressing mouse button 0? At first I thought it might be the EventSystem, but I’ve removed that from the scene so I’ve simply got this script, camera, light in the scene.

Thanks for any help.
Cheers

2

It’s been a longstanding (although I’m not sure officially documented) behaviour that the first finger touch on a touch device maps to a LMB click. This makes it easy to quickly design interfaces that work on both touch and mouse by only listening for GetMouseButton(0), though I wouldn’t rely on it and recommend you use the “proper” Input.touches input.