CameraRotateAroundTarget

var target : Transform;
var distance = 10.0;
var xSpeed = 250.0;
var ySpeed = 120.0;
var yMinLimit = -20;
var yMaxLimit = 80;
var zoomRate = 25;
var yOffset:float;

private var x = 0.0;
private var y = 0.0;

@script AddComponentMenu("Camera-Control/Mouse Orbit")

function Start () {
var t:Transform = GameObject.Find("Camera Target").transform;
if(t)
target = t;
var angles = transform.eulerAngles;
x = angles.y;
y = angles.x;
}

function Update () {
if (!Input.GetMouseButton(0)){

if (target) {

x += Input.GetAxis("Mouse X") * xSpeed * Time.deltaTime;
y -= Input.GetAxis("Mouse Y") * ySpeed * Time.deltaTime;

distance += -(Input.GetAxis("Mouse ScrollWheel") * Time.deltaTime) * zoomRate * Mathf.Abs(distance);

y = ClampAngle(y, yMinLimit, yMaxLimit);

var rotation = Quaternion.Euler(y, x, 0);
var t:Vector3 = Vector3(target.position.x, target.position.y + yOffset, target.position.z);
var position = rotation * Vector3(0.0, 0.0, -distance) + t;

transform.rotation = rotation;
transform.position = position;

}

}
}

static function ClampAngle (angle : float, min : float, max : float) {
if (angle < -360)
angle += 360;
if (angle > 360)
angle -= 360;
return Mathf.Clamp (angle, min, max);
}