using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Hilbert : MonoBehaviour {

    public int m_order = 3;
    public float m_spacing = 1;
    private int m_size;
    private float[] m_hilbert;
    private Vector3 m_lastPoint = new Vector3(0, 0, 0);
    private Vector3[] m_rotation = new Vector3[5] { new Vector3(-90, 0, -90), new Vector3(0, 90, 90),
        new Vector3(180, 0, 0), new Vector3(0, -90, -90), new Vector3(-90, 0, 90)};

    // Use this for initialization
    void Start ()
    {
        m_size = Mathf.FloorToInt(Mathf.Pow(8, (float)m_order));
        m_hilbert = new float[m_size];

        for(int i = 0; i<m_size; i++)
        {
            m_hilbert[i] = i*255 / m_size;
        }

        drawHilbert();
    }

    // Update is called once per frame
    void Update()
    {

    }

    void drawHilbert()
    {
        writeCell(0, 0, this.transform.position, this.transform.right, this.transform.up, this.transform.forward);
    }

    int writeCell(int order, int index, Vector3 position, Vector3 right, Vector3 up, Vector3 forward)
    {
        if (order >= m_order)
        {
            if (index != 0)
            {
                Debug.DrawLine(m_lastPoint, position, Color.HSVToRGB(m_hilbert[index - 1] / 256, 1, 1), 100);
            }
            m_lastPoint = position;
            return index+1;
        } else
        {
            index = writeCell(order + 1, index, position + (- forward - up - right) * (m_spacing / Mathf.Pow(2, (float)order)),
                Quaternion.Euler(m_rotation[0]) * right, Quaternion.Euler(m_rotation[0]) * up, Quaternion.Euler(m_rotation[0]) * forward);
            index = writeCell(order + 1, index, position + (forward - up - right) * (m_spacing / Mathf.Pow(2, (float)order)),
            Quaternion.Euler(m_rotation[1]) * right, Quaternion.Euler(m_rotation[1]) * up, Quaternion.Euler(m_rotation[1]) * forward);
            index = writeCell(order + 1, index, position + (forward + up - right) * (m_spacing / Mathf.Pow(2, (float)order)),
            Quaternion.Euler(m_rotation[1]) * right, Quaternion.Euler(m_rotation[1]) * up, Quaternion.Euler(m_rotation[1]) * forward);
            index = writeCell(order + 1, index, position + (- forward + up - right) * (m_spacing / Mathf.Pow(2, (float)order)),
            Quaternion.Euler(m_rotation[2]) * right, Quaternion.Euler(m_rotation[2]) * up, Quaternion.Euler(m_rotation[2]) * forward);
            index = writeCell(order + 1, index, position + (-forward + up + right) * (m_spacing / Mathf.Pow(2, (float)order)),
            Quaternion.Euler(m_rotation[2]) * right, Quaternion.Euler(m_rotation[2]) * up, Quaternion.Euler(m_rotation[2]) * forward);
            index = writeCell(order + 1, index, position + (forward + up + right) * (m_spacing / Mathf.Pow(2, (float)order)),
            Quaternion.Euler(m_rotation[3]) * right, Quaternion.Euler(m_rotation[3]) * up, Quaternion.Euler(m_rotation[3]) * forward);
            index = writeCell(order + 1, index, position + (forward - up + right) * (m_spacing / Mathf.Pow(2, (float)order)),
            Quaternion.Euler(m_rotation[3]) * right, Quaternion.Euler(m_rotation[3]) * up, Quaternion.Euler(m_rotation[3]) * forward);
            index = writeCell(order + 1, index, position + (-forward - up + right) * (m_spacing / Mathf.Pow(2, (float)order)),
            Quaternion.Euler(m_rotation[4]) * right, Quaternion.Euler(m_rotation[4]) * up, Quaternion.Euler(m_rotation[4]) * forward);
            return index;
        }
    }
}