using UnityEngine;
using System.Collections;

public class OrbitCamera : MonoBehaviour {
    
    // the target to follow (orbit around)
    [SerializeField]
    private Transform target;

    // the rotation speed for the camera
    public float rotationSpeed = 1.5f;

    private float rotY;        // current rotation of Y
    public Vector3 offset = new Vector3(0, 2.5f, -3.5f);    // the distance at which to follow the player


	// Use this for initialization
	void Start () {
        rotY = transform.eulerAngles.y;
	}
	
	// LateUpdate is called after all other Update methods
	void LateUpdate () {
        // Get the input on the horizontal axis
        float horInput = Input.GetAxis("Horizontal");

        if (horInput != 0) // keyboard input along horizontal axis
        {
            // Rotate the camera slowly using the keyboard horizontal input (arrow keys ...)
            rotY += horInput * rotationSpeed;
        }
        else
        {
            // Rotate the camera quickly with the mouse
            rotY += Input.GetAxis("Mouse X") * rotationSpeed * 3;
        }

        // Euler angles are limited by a phenomenon called "gimbal lock", which prevents them from measuring orientation when the pitch angle approaches +/- 90 degrees.
        // Euler angles will always fail to produce reliable estimates when the pitch angle approaches 90 degrees. 
        Quaternion rotation = Quaternion.Euler(0, rotY, 0);

        // update the camera's offset position according to the camera's rotation
        transform.position = target.position + (rotation * offset);
        
        // face the target
        transform.LookAt(target);
    }
}