using UnityEngine;
using System.Collections;
 
public class Camera3D : MonoBehaviour {
   
    public GameObject Target;
 
    float Distance = 9.0f;
 
    float RotationVelocityX;
    float RotationVelocityY;
    float RotationSpeedX = 25.0f;
    float RotationSpeedY = 25.0f;
    float ZoomVelocity;
    float ZoomSpeed = 20.0f;
    float ZoomMin = 7.2f, ZoomMax = 15f;
    float RotationLimitY = 90;
 
    float AngleX;
    float AngleY;
 
    private Quaternion Rotation;
 
    void Start()
    {
        var angles = transform.eulerAngles;
        AngleX = angles.y;
        AngleY = angles.x;
    }
 
    public void SetTarget(GameObject target)
    {
        Target = target;
    }
 
    void FixedUpdate()
    {
        if (Target)
        {
            // Rotate
            if (Input.GetMouseButton(1))
            {
                RotationVelocityX += Input.GetAxis("Mouse X") * RotationSpeedX * Time.deltaTime;
                RotationVelocityY += Input.GetAxis("Mouse Y") * RotationSpeedY * Time.deltaTime;
            }
 
            AngleX += RotationVelocityX;
            AngleY -= RotationVelocityY;
            AngleY = ClampAngle(AngleY, -RotationLimitY, RotationLimitY);
 
            Rotation = Quaternion.Euler(AngleY, AngleX, 0);
 
            RotationVelocityX = Mathf.Lerp(RotationVelocityX, 0, 0.1f);
            RotationVelocityY = Mathf.Lerp(RotationVelocityY, 0, 0.1f);
 
 
            // Zoom
            float scroll = Input.GetAxis("Mouse ScrollWheel");
            ZoomVelocity += Time.deltaTime * scroll * ZoomSpeed;
 
            Distance += ZoomVelocity;
 
            ZoomVelocity = Mathf.Lerp(ZoomVelocity, 0, 0.1f);
 
            //         if (Input.GetKey (KeyCode.Z)) {
            //  Distance -= Time.deltaTime * ZoomSpeed;
            //} else if (Input.GetKey (KeyCode.A)) {
            //  Distance += Time.deltaTime * ZoomSpeed;            
            //}
            Distance = Mathf.Clamp(Distance, ZoomMin, ZoomMax);
            transform.Translate(0, 0, Distance);
 
            // Position
            transform.rotation = Rotation;
            transform.position = Rotation * new Vector3(0.0f, 0.0f, -Distance) + Target.Center;
        }
    }
 
    static float ClampAngle(float angle, float min, float max)
    {
        if (angle < -360)
            angle += 360;
        if (angle > 360)
            angle -= 360;
        return Mathf.Clamp(angle, min, max);
    }
}