// http://www.unity3d-france.com/unity/phpBB3/viewtopic.php?f=24&t=5409

using System.Collections.Generic;
using System.Linq;
using UnityEngine;
 
public  class GLDebug : MonoBehaviour
{
        private struct Line
        {
                public Vector3 start;
                public Vector3 end;
                public Color color;
                public float startTime;
                public float duration;
               
                public Line (Vector3 start, Vector3 end, Color color, float startTime, float duration)
                {
                        this.start = start;
                        this.end = end;
                        this.color = color;
                        this.startTime = startTime;
                        this.duration = duration;
                }
               
                public bool DurationElapsed (bool drawLine)
                {
                        if (drawLine)
                        {
                                GL.Color (color);
                                GL.Vertex (start);
                                GL.Vertex (end);
                        }
                        return Time.time - startTime >= duration;
                }
        }
       
        private static GLDebug instance;
        private static Material matZOn;
        private static Material matZOff;
       
        public KeyCode toggleKey;
        public bool displayLines = true;
#if UNITY_EDITOR
        public bool displayGizmos = true;
#endif
        //public ScreenRect rect = new ScreenRect (0, 0, 150, 20);
       
	private List<Line> linesZOn = new List<Line> ();
	private List<Line> linesZOff = new List<Line> ();
//        private float milliseconds;
       
	public Shader zOnShader;
	public Shader zOffShader;


        void Awake ()
        {
                if (instance)
                {
                        DestroyImmediate (this);
                        return;
                }
                instance = this;
                SetMaterial ();
        
				if (null == this.GetComponent<Camera> ())
				{
					Debug.LogError ("There should be camera attached to the same game object");
				}

        }
       
    void SetMaterial ()
	{
		matZOn = new Material(this.zOnShader);
			matZOn.hideFlags = HideFlags.HideAndDontSave;
            //matZOn.shader.hideFlags = HideFlags.HideAndDontSave;

		matZOff = new Material(this.zOffShader);
            matZOff.hideFlags = HideFlags.HideAndDontSave;
            //matZOff.shader.hideFlags = HideFlags.HideAndDontSave;
        }
       
        void Update ()
        {
                if (Input.GetKeyDown (toggleKey))
                        displayLines = !displayLines;
               
                if (!displayLines)
                {
//                        Stopwatch timer = Stopwatch.StartNew ();
                       
                        linesZOn = linesZOn.Where (l => !l.DurationElapsed (false)).ToList ();
                        linesZOff = linesZOff.Where (l => !l.DurationElapsed (false)).ToList ();
                       
//                        timer.Stop ();
//                        milliseconds = timer.Elapsed.Ticks / 10000f;
                }
        }
       
        /*void OnGUI ()
        {
                GUI.Label (rect, "GLDebug : " + milliseconds.ToString ("f") + " ms");
        }*/
       
#if UNITY_EDITOR
        void OnDrawGizmos ()
        {
                if (!displayGizmos || !Application.isPlaying)
                        return;
                for (int i = 0; i < linesZOn.Count; i++)
                {
                        Gizmos.color = linesZOn[i].color;
                        Gizmos.DrawLine (linesZOn[i].start, linesZOn[i].end);
                }
                for (int i = 0; i < linesZOff.Count; i++)
                {
                        Gizmos.color = linesZOff[i].color;
                        Gizmos.DrawLine (linesZOff[i].start, linesZOff[i].end);
                }
        }
#endif
       
        void OnPostRender ()
        {
                if (!displayLines) return;
               
    //            Stopwatch timer = Stopwatch.StartNew ();
               
                matZOn.SetPass (0);
                GL.Begin (GL.LINES);
                linesZOn = linesZOn.Where (l => !l.DurationElapsed (true)).ToList ();
                GL.End ();
               
                matZOff.SetPass (0);
                GL.Begin (GL.LINES);
                linesZOff = linesZOff.Where (l => !l.DurationElapsed (true)).ToList ();
                GL.End ();
               
  //              timer.Stop ();
//                milliseconds = timer.Elapsed.Ticks / 10000f;
        }
 
        private static void DrawLine (Vector3 start, Vector3 end, Color color, float duration = 0, bool depthTest = false)
        {
                if (duration == 0 && !instance.displayLines)
                        return;
                if (start == end)
                        return;
                if (depthTest)
                        instance.linesZOn.Add (new Line (start, end, color, Time.time, duration));
                else
                        instance.linesZOff.Add (new Line (start, end, color, Time.time, duration));
        }
 
        /// <summary>
        /// Draw a line from start to end with color for a duration of time and with or without depth testing.
        /// If duration is 0 then the line is rendered 1 frame.
        /// </summary>
        /// <param name="start">Point in world space where the line should start.</param>
        /// <param name="end">Point in world space where the line should end.</param>
        /// <param name="color">Color of the line.</param>
        /// <param name="duration">How long the line should be visible for.</param>
        /// <param name="depthTest">Should the line be obscured by objects closer to the camera ?</param>
        public static void DrawLine (Vector3 start, Vector3 end, Color? color = null, float duration = 0, bool depthTest = false)
        {
                DrawLine (start, end, color ?? Color.white, duration, depthTest);
        }
 
        /// <summary>
        /// Draw a line from start to start + dir with color for a duration of time and with or without depth testing.
        /// If duration is 0 then the ray is rendered 1 frame.
        /// </summary>
        /// <param name="start">Point in world space where the ray should start.</param>
        /// <param name="dir">Direction and length of the ray.</param>
        /// <param name="color">Color of the ray.</param>
        /// <param name="duration">How long the ray should be visible for.</param>
        /// <param name="depthTest">Should the ray be obscured by objects closer to the camera ?</param>
        public static void DrawRay (Vector3 start, Vector3 dir, Color? color = null, float duration = 0, bool depthTest = false)
        {
                if (dir == Vector3.zero)
                        return;
                DrawLine (start, start + dir, color, duration, depthTest);
        }
       
        /// <summary>
        /// Draw an arrow from start to end with color for a duration of time and with or without depth testing.
        /// If duration is 0 then the arrow is rendered 1 frame.
        /// </summary>
        /// <param name="start">Point in world space where the arrow should start.</param>
        /// <param name="end">Point in world space where the arrow should end.</param>
        /// <param name="arrowHeadLength">Length of the 2 lines of the head.</param>
        /// <param name="arrowHeadAngle">Angle between the main line and each of the 2 smaller lines of the head.</param>
        /// <param name="color">Color of the arrow.</param>
        /// <param name="duration">How long the arrow should be visible for.</param>
        /// <param name="depthTest">Should the arrow be obscured by objects closer to the camera ?</param>
        public static void DrawLineArrow (Vector3 start, Vector3 end, float arrowHeadLength = 0.25f, float arrowHeadAngle = 20, Color? color = null, float duration = 0, bool depthTest = false)
        {
                DrawArrow (start, end - start, arrowHeadLength, arrowHeadAngle, color, duration, depthTest);
        }
       
        /// <summary>
        /// Draw an arrow from start to start + dir with color for a duration of time and with or without depth testing.
        /// If duration is 0 then the arrow is rendered 1 frame.
        /// </summary>
        /// <param name="start">Point in world space where the arrow should start.</param>
        /// <param name="dir">Direction and length of the arrow.</param>
        /// <param name="arrowHeadLength">Length of the 2 lines of the head.</param>
        /// <param name="arrowHeadAngle">Angle between the main line and each of the 2 smaller lines of the head.</param>
        /// <param name="color">Color of the arrow.</param>
        /// <param name="duration">How long the arrow should be visible for.</param>
        /// <param name="depthTest">Should the arrow be obscured by objects closer to the camera ?</param>
        public static void DrawArrow (Vector3 start, Vector3 dir, float arrowHeadLength = 0.25f, float arrowHeadAngle = 20, Color? color = null, float duration = 0, bool depthTest = false)
        {
                if (dir == Vector3.zero)
                        return;
                DrawRay (start, dir, color, duration, depthTest);
                Vector3 right = Quaternion.LookRotation (dir) * Quaternion.Euler (0, 180 + arrowHeadAngle, 0) * Vector3.forward;
                Vector3 left  = Quaternion.LookRotation (dir) * Quaternion.Euler (0, 180 - arrowHeadAngle, 0) * Vector3.forward;
                DrawRay (start + dir, right * arrowHeadLength, color, duration, depthTest);
                DrawRay (start + dir, left  * arrowHeadLength, color, duration, depthTest);
        }
       
        /// <summary>
        /// Draw a square with color for a duration of time and with or without depth testing.
        /// If duration is 0 then the square is renderer 1 frame.
        /// </summary>
        /// <param name="pos">Center of the square in world space.</param>
        /// <param name="rot">Rotation of the square in euler angles in world space.</param>
        /// <param name="scale">Size of the square.</param>
        /// <param name="color">Color of the square.</param>
        /// <param name="duration">How long the square should be visible for.</param>
        /// <param name="depthTest">Should the square be obscured by objects closer to the camera ?</param>
        public static void DrawSquare (Vector3 pos, Vector3? rot = null, Vector3? scale = null, Color? color = null, float duration = 0, bool depthTest = false)
        {
                DrawSquare (Matrix4x4.TRS (pos, Quaternion.Euler (rot ?? Vector3.zero), scale ?? Vector3.one), color, duration, depthTest);
        }
        /// <summary>
        /// Draw a square with color for a duration of time and with or without depth testing.
        /// If duration is 0 then the square is renderer 1 frame.
        /// </summary>
        /// <param name="pos">Center of the square in world space.</param>
        /// <param name="rot">Rotation of the square in world space.</param>
        /// <param name="scale">Size of the square.</param>
        /// <param name="color">Color of the square.</param>
        /// <param name="duration">How long the square should be visible for.</param>
        /// <param name="depthTest">Should the square be obscured by objects closer to the camera ?</param>
        public static void DrawSquare (Vector3 pos, Quaternion? rot = null, Vector3? scale = null, Color? color = null, float duration = 0, bool depthTest = false)
        {
                DrawSquare (Matrix4x4.TRS (pos, rot ?? Quaternion.identity, scale ?? Vector3.one), color, duration, depthTest);
        }
        /// <summary>
        /// Draw a square with color for a duration of time and with or without depth testing.
        /// If duration is 0 then the square is renderer 1 frame.
        /// </summary>
        /// <param name="matrix">Transformation matrix which represent the square transform.</param>
        /// <param name="color">Color of the square.</param>
        /// <param name="duration">How long the square should be visible for.</param>
        /// <param name="depthTest">Should the square be obscured by objects closer to the camera ?</param>
        public static void DrawSquare (Matrix4x4 matrix, Color? color = null, float duration = 0, bool depthTest = false)
        {
                Vector3
                        p_1     = matrix.MultiplyPoint3x4 (new Vector3 ( .5f, 0,  .5f)),
                        p_2     = matrix.MultiplyPoint3x4 (new Vector3 ( .5f, 0, -.5f)),
                        p_3     = matrix.MultiplyPoint3x4 (new Vector3 (-.5f, 0, -.5f)),
                        p_4     = matrix.MultiplyPoint3x4 (new Vector3 (-.5f, 0,  .5f));
               
                DrawLine (p_1, p_2, color, duration, depthTest);
                DrawLine (p_2, p_3, color, duration, depthTest);
                DrawLine (p_3, p_4, color, duration, depthTest);
                DrawLine (p_4, p_1, color, duration, depthTest);
        }
       
        /// <summary>
        /// Draw a cube with color for a duration of time and with or without depth testing.
        /// If duration is 0 then the square is renderer 1 frame.
        /// </summary>
        /// <param name="pos">Center of the cube in world space.</param>
        /// <param name="rot">Rotation of the cube in euler angles in world space.</param>
        /// <param name="scale">Size of the cube.</param>
        /// <param name="color">Color of the cube.</param>
        /// <param name="duration">How long the cube should be visible for.</param>
        /// <param name="depthTest">Should the cube be obscured by objects closer to the camera ?</param>
        public static void DrawCube (Vector3 pos, Vector3? rot = null, Vector3? scale = null, Color? color = null, float duration = 0, bool depthTest = false)
        {
                DrawCube (Matrix4x4.TRS (pos, Quaternion.Euler (rot ?? Vector3.zero), scale ?? Vector3.one), color, duration, depthTest);
        }
        /// <summary>
        /// Draw a cube with color for a duration of time and with or without depth testing.
        /// If duration is 0 then the square is renderer 1 frame.
        /// </summary>
        /// <param name="pos">Center of the cube in world space.</param>
        /// <param name="rot">Rotation of the cube in world space.</param>
        /// <param name="scale">Size of the cube.</param>
        /// <param name="color">Color of the cube.</param>
        /// <param name="duration">How long the cube should be visible for.</param>
        /// <param name="depthTest">Should the cube be obscured by objects closer to the camera ?</param>
        public static void DrawCube (Vector3 pos, Quaternion? rot = null, Vector3? scale = null, Color? color = null, float duration = 0, bool depthTest = false)
        {
                DrawCube (Matrix4x4.TRS (pos, rot ?? Quaternion.identity, scale ?? Vector3.one), color, duration, depthTest);
        }
        /// <summary>
        /// Draw a cube with color for a duration of time and with or without depth testing.
        /// If duration is 0 then the square is renderer 1 frame.
        /// </summary>
        /// <param name="matrix">Transformation matrix which represent the cube transform.</param>
        /// <param name="color">Color of the cube.</param>
        /// <param name="duration">How long the cube should be visible for.</param>
        /// <param name="depthTest">Should the cube be obscured by objects closer to the camera ?</param>
        public static void DrawCube (Matrix4x4 matrix, Color? color = null, float duration = 0, bool depthTest = false)
        {
                Vector3
                        down_1  = matrix.MultiplyPoint3x4 (new Vector3 ( .5f, -.5f,  .5f)),
                        down_2  = matrix.MultiplyPoint3x4 (new Vector3 ( .5f, -.5f, -.5f)),
                        down_3  = matrix.MultiplyPoint3x4 (new Vector3 (-.5f, -.5f, -.5f)),
                        down_4  = matrix.MultiplyPoint3x4 (new Vector3 (-.5f, -.5f,  .5f)),
                        up_1    = matrix.MultiplyPoint3x4 (new Vector3 ( .5f,  .5f,  .5f)),
                        up_2    = matrix.MultiplyPoint3x4 (new Vector3 ( .5f,  .5f, -.5f)),
                        up_3    = matrix.MultiplyPoint3x4 (new Vector3 (-.5f,  .5f, -.5f)),
                        up_4    = matrix.MultiplyPoint3x4 (new Vector3 (-.5f,  .5f,  .5f));
               
                DrawLine (down_1, down_2, color, duration, depthTest);
                DrawLine (down_2, down_3, color, duration, depthTest);
                DrawLine (down_3, down_4, color, duration, depthTest);
                DrawLine (down_4, down_1, color, duration, depthTest);
               
                DrawLine (down_1, up_1, color, duration, depthTest);
                DrawLine (down_2, up_2, color, duration, depthTest);
                DrawLine (down_3, up_3, color, duration, depthTest);
                DrawLine (down_4, up_4, color, duration, depthTest);
               
                DrawLine (up_1, up_2, color, duration, depthTest);
                DrawLine (up_2, up_3, color, duration, depthTest);
                DrawLine (up_3, up_4, color, duration, depthTest);
                DrawLine (up_4, up_1, color, duration, depthTest);
        }
	
	
		// EXTRAS
	    public static void DrawCircle (Vector3 center, float radius, Color? color = null, float duration = 0, bool depthTest = false)
        {
//            float degRad = Mathf.PI / 180;
			for(float theta = 0.0f; theta < (2*Mathf.PI); theta += 0.2f)
			{
				Vector3 ci = (new Vector3(Mathf.Cos(theta) * radius + center.x, Mathf.Sin(theta) * radius + center.y, center.z));
				DrawLine (ci, ci+new Vector3(0,0.02f,0), color, duration, depthTest);
			}
        }
	
}