unity3d 带缓冲的镜头拉近效果

/大家应该见过，一些游戏中，当玩家发现了某样东西，摄像机会马上移动过去，但在快到的时候会减慢速度，这个代码实现的就是那个效果。
//SmoothFollowWithCameraBumper.js

 var target : Transform;
 var distance : float = 3.0;
 var height : float = 1.0;
 var damping : float = 5.0;
 var smoothRotation : boolean = true;
 var rotationDamping : float = 10.0;

 var targetLookAtOffset : Vector3;     // allows offsetting of camera lookAt, very useful for low bumper heights

 var bumperDistanceCheck : float = 2.5;  // length of bumper ray
 var bumperCameraHeight : float = 1.0;   // adjust camera height while bumping
 var bumperRayOffset : Vector3;    // allows offset of the bumper ray from target origin

 function FixedUpdate() {

     var wantedPosition = target.TransformPoint(0, height, -distance);

     // check to see if there is anything behind the target
     var hit : RaycastHit;
     var back = target.transform.TransformDirection(-1 * Vector3.forward);

     // cast the bumper ray out from rear and check to see if there is anything behind
     if (Physics.Raycast(target.TransformPoint(bumperRayOffset), back, hit, bumperDistanceCheck)) {
         // clamp wanted position to hit position
         wantedPosition.x = hit.point.x;
         wantedPosition.z = hit.point.z;
         wantedPosition.y = Mathf.Lerp(hit.point.y + bumperCameraHeight, wantedPosition.y, Time.deltaTime * damping);
     }

     transform.position = Vector3.Lerp(transform.position, wantedPosition, Time.deltaTime * damping);

     var lookPosition : Vector3 = target.TransformPoint(targetLookAtOffset);

     if (smoothRotation) {
         var wantedRotation : Quaternion = Quaternion.LookRotation(lookPosition - transform.position, target.up);
         transform.rotation = Quaternion.Slerp(transform.rotation, wantedRotation, Time.deltaTime * rotationDamping);
     } else {
         transform.rotation = Quaternion.LookRotation(lookPosition - transform.position, target.up);
     }
 }