private var character :CharacterController;

private var speed =0.0;

private var trans:Transform;

private var targetRot:Quaternion;

 var rotationSpeed = 90 ;

 var pedalImpulse = 3.5;

 var maxSpeed = 15;

 var decayRate = 0.1;

 var jumpSpeed : float = 8.0;

 var raycastMask :LayerMask;

 

function Start()

{

   character = GetComponent(CharacterController);

   trans= transform ;

}

function pedal()

{

    speed += pedalImpulse;

    speed = Mathf.Min(speed, maxSpeed);

}

function Update ()

{

   var horizontal = Input.GetAxis("Horizontal");

   var Vertical = Input.GetAxis("Vertical");

   transform.Rotate(0,rotationSpeed*horizontal*Time.deltaTime,0);

  

   if(character.isGrounded)

     pedal();

   //For normalized vectors Dot returns 1 if they point in exactly the same direction, -1

   //if they point in completely opposite directions and zero if the vectors are perpendicular.

   var moveDirection = trans.forward*speed*Vertical;

   var upright = Vector3.Dot(trans.forward,Vector3.up);//upright >0 是向上行走 <0向下行走

   Debug.Log(upright.ToString());

   //we want fake gravity when the character becomes upright

   //become the characterController dosen`t rotate

  

   //当x>0，sign(x)=1;当x=0，sign(x)=0; 当x<0， sign(x)=-1

   //Clamp01  Clamps value between 0 and 1 and returns value.

   moveDirection += Vector3.Lerp( Physics.gravity,Mathf.Sign(upright)

               * -trans.forward * Physics.gravity.magnitude,

               Mathf.Clamp01(Mathf.Abs(upright)));

  

   character.Move(moveDirection*Time.deltaTime);

  

   //旋转角色根据地形法线

   var ray = new Ray(trans.position+Vector3.up,-Vector3.up);

   var hit : RaycastHit;

   if (character.isGrounded && Physics.Raycast(ray,hit,100,raycastMask))

   {

       var targetRight = Vector3.Cross(hit.normal,trans.forward);

       var targetForward = Vector3.Cross(targetRight,hit.normal);

       targetRot = Quaternion.LookRotation(targetForward,hit.normal);

   }

  

   trans.rotation = Quaternion.Slerp(trans.rotation,targetRot,5*Time.deltaTime);

  

   if(character.isGrounded)

   {

       if(speed<0.3)

         speed=0;

    else

    {

       speed -= decayRate*Time.deltaTime*speed;

    }

   }

  

  

}