Meaning of virtual axis

I am starting developing with Unity3D. I have been searching for an explanation of what a virtual axis means. This term is used in, form example, Input.GetAxis. Can someone please explain or let me know where can I find information about this issue?

Thanks in advance.

 

Maybe this helps?

http://docs.unity3d.com/Documentation/Manual/Input.html

 

I appreciate your response.
Yes, the link gives more information of what I actually had, but there is still something that I do not understand.
(By the way, I am totally new to Unity3D, this is why I am having trouble with some concepts.)
Documentation says that an axis has a value between -1 and 1, and that zero is neutral position.
Does this mean that, for example, an axis can take a value of 0.3 or -0.45?
What is the correct interpretation if Input.GetAxis("Horizontal") or Input.GetAxis("Vertical") or Input.GetAxis("Jump") has a positive or negative value?
Are "Horizontal", "Vertical" and "Jump" all virtual axis?

Respectfully,
Jorge Maldonado

 

The Axis takes input and puts it into an easy to use value for you to use.

The default keys for Vertical Axis are "Up Arrow" "Down Arrow" "W" and "S".
Default Keys for Horizontal are "Left Arrow" "Right Arrow" "A" and "D".

Both also recognize controller and joystick input.

Using the Input.GetAxis will slowly increment the Axis towards 1 or -1 depending on the direction of the Input.
So if you push the Up Arrow the Input.GetAxis would start towards 1. A couple of frames of this may look like this.

Frame 1: Horizontal Axis = 0.4
Frame 2: Horizontal Axis = 0.8
Frame 3 : Horizontal Axis = 1
Frame 4 : Horizontal Axis = 1
...

If you then stop pressing the Up key or alternately press the Down Key it will begin going to 0 (and then -1 if pressing down) in a similar fashion.

They count from 1 to -1 and have 0 be neutral because then it is easy to do something like.

function Update ()
{
var movement = Input.GetAxis("Horizontal") * 20 ;
transform.Translate(movement, 0, 0);
}

when pressing left movement will come out to be -20
when pressing nothing it will come out to 0
and pressing right will give you 20

With just that small bit of code you can move an object left to right (left being -1, right being 1) 20 units each frame.


If you don't want to have those few frames where the Axis is 0.33 or something like that then you can use GetAxisRaw which is essentially the same thing but will always return a whole number (-1, 0, or 1).

 

THANK YOU SO MUCH GALE.
Your explanation is great. My question is now completely answered.

 

Thank you GALE! The explanation was very helpful.

 

Thanks

 

Thanks!!

 

Your explanation is great.