Simple RTS Camera

RTSCamera.cs

using UnityEngine;
using System.Collections;


public class RTSCamera : MonoBehaviour {
	
	public float scrollArea = 50f;
	public float scrollSpeed = 50f;
	public float rotateSpeed = 4f;
	
	// camera look at position
	Vector3 _followPos;
	public Vector3 followPos {
		get {
			return _followPos;	
		}
		
		set {
			value.x = Mathf.Clamp(value.x, 0, 200); //clamp  position
			value.z = Mathf.Clamp(value.z, 0, 200);
			_followPos = value;
		}
	}
	Vector3  currentPos;  // current camera look at position

	float angleY = 0f;	
	
	//height factor
	float  current = 0.5f; //[0,1]
	float  target = 0.5f; //[0,1]
	
	float  lerpSpeed = 1f;
	
	void Start() {
		followPos = new Vector3(100, 0, 100);	
	}
	// Update is called once per frame
	void Update () {
		
		HandleInput();
		
		
		lerpSpeed = Mathf.Lerp(lerpSpeed, 1f, Time.deltaTime * 5);
		float factor = Mathf.Clamp01(Time.deltaTime*10f*lerpSpeed);
		currentPos = Vector3.Lerp(currentPos, followPos, factor);
		
		float angleX = Mathf.Lerp(30,80,current);
		Quaternion targetRot = Quaternion.Euler(angleX, angleY,0.0f);
		Vector3 offset = Vector3.forward * Mathf.Lerp(8f,30f,current);
		transform.position = Vector3.Lerp(transform.position, currentPos - targetRot*offset, factor);
		transform.rotation = Quaternion.Slerp(transform.rotation, targetRot, factor);
		
	}
	
	void FixedUpdate() {
		RaycastHit hit;
		_followPos.y = 0;
		if(Physics.Raycast(followPos+1000*Vector3.up, -Vector3.up, out hit, 1000f, 1<<LayerMask.NameToLayer("Terrain"))) {
			_followPos.y = hit.point.y;
		}
	}

	void HandleInput() {
		
		float posx = Input.mousePosition.x;
		float posy = Input.mousePosition.y;
		float factor = Mathf.Min(1.0f, Time.deltaTime * 10f);
		target = Mathf.Clamp01(target - Input.GetAxis("Mouse ScrollWheel") * 0.25f);
		current = current * (1.0f - factor) + target * factor;

		if(Input.GetMouseButton(1)) {
			angleY += Input.GetAxis("Mouse X") * rotateSpeed ;
		} 
		else {
			Vector3 forward = transform.forward;
			Vector3 right = transform.right;
			forward.y = 0;
			right.y = 0;
			forward.Normalize();
			right.Normalize();
			if (posx < scrollArea) {followPos += -scrollSpeed *right* Time.deltaTime;}
			if (posx >= Screen.width-scrollArea) {followPos += scrollSpeed * right*Time.deltaTime;}
			if (posy < scrollArea) {followPos += -forward * scrollSpeed * Time.deltaTime;}
			if (posy >= Screen.height-scrollArea) {followPos += forward*scrollSpeed * Time.deltaTime;}
		}
	}
}