Can someone explain this MouseMove script to me :)

Questions & Answers
1

Hi guys, i was wondering if you could explain something to me. I just made a script called mouse x basically its my own mouse move script :). But i came across a code that got me thinking why it is there and if i remove why it stops my rotation on the script. the script is here:

public enum RotationAxis {MouseX = 1}
  var RotationAxisX = RotationAxis.MouseX;

  var sensitivityX : float = 400f;

  public var minimumX : float = -360;

  public var maximumX : float = 360;

  public var rotationX : float = 0;

  var OriginalRotation : Quaternion;

function start(){

OriginalRotation = transform.localRotation;

}

function Update () {

    if(RotationAxisX == RotationAxis.MouseX){

    rotationX += Input.GetAxis("Mouse X") * sensitivityX * Time.deltaTime;

    rotationX = ClampAngle (rotationX, minimumX, maximumX);

    OriginalRotation = XQuaternion = Quaternion.AngleAxis(rotationX, Vector3.up);

    transform.localRotation = OriginalRotation * XQuaternion;

}
}

function ClampAngle (angle, min , max ):float 
{

   if(angle < -360f){
   angle += 360;
   }
   if(angle >360){
   angle -= 360;

   }
   return Mathf.Clamp (angle,min, max);
}

basically its the "Function ClampAngle " line that contains the code i am talking about. the code of line is 

 return Mathf.Clamp (angle, min, max);

this is the line of code that i am talking about if i delete this line of code it makes the x rotation completely stop and why is that :)

secondly i was wondering if someone can tell me what an Quaternion is :) thank you very much in advance :)

MCHALO

2

If you remove that line then your ClampAngle function does not return anything. You use this in the following line to set the X rotation:

rotationX = ClampAngle (rotationX, minimumX, maximumX);

If ClampAngle does not return anything then the X rotation is never updated.

A quaternion is a mathemetical model to represent a rotation in a compact way. They are extremely difficult to understand fully and it's easiest to learn what they do by experimenting or modifying existing code.

http://unity3d.com/support/documentation/ScriptReference/Quaternion.html