(* Copyright (c) Mark J. Kilgard, 1994. *)

(* (c) Copyright 1993, Silicon Graphics, Inc.
 * ALL RIGHTS RESERVED
 * Permission to use, copy, modify, and distribute this software for
 * any purpose and without fee is hereby granted, provided that the above
 * copyright notice appear in all copies and that both the copyright notice
 * and this permission notice appear in supporting documentation, and that
 * the name of Silicon Graphics, Inc. not be used in advertising
 * or publicity pertaining to distribution of the software without specific,
 * written prior permission.
 *
 * THE MATERIAL EMBODIED ON THIS SOFTWARE IS PROVIDED TO YOU "AS-IS"
 * AND WITHOUT WARRANTY OF ANY KIND, EXPRESS, IMPLIED OR OTHERWISE,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY OR
 * FITNESS FOR A PARTICULAR PURPOSE.  IN NO EVENT SHALL SILICON
 * GRAPHICS, INC.  BE LIABLE TO YOU OR ANYONE ELSE FOR ANY DIRECT,
 * SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY
 * KIND, OR ANY DAMAGES WHATSOEVER, INCLUDING WITHOUT LIMITATION,
 * LOSS OF PROFIT, LOSS OF USE, SAVINGS OR REVENUE, OR THE CLAIMS OF
 * THIRD PARTIES, WHETHER OR NOT SILICON GRAPHICS, INC.  HAS BEEN
 * ADVISED OF THE POSSIBILITY OF SUCH LOSS, HOWEVER CAUSED AND ON
 * ANY THEORY OF LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE
 * POSSESSION, USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 * US Government Users Restricted Rights
 * Use, duplication, or disclosure by the Government is subject to
 * restrictions set forth in FAR 52.227.19(c)(2) or subparagraph
 * (c)(1)(ii) of the Rights in Technical Data and Computer Software
 * clause at DFARS 252.227-7013 and/or in similar or successor
 * clauses in the FAR or the DOD or NASA FAR Supplement.
 * Unpublished-- rights reserved under the copyright laws of the
 * United States.  Contractor/manufacturer is Silicon Graphics,
 * Inc., 2011 N.  Shoreline Blvd., Mountain View, CA 94039-7311.
 *
 * OpenGL(TM) is a trademark of Silicon Graphics, Inc.
 *)

(*  depthcue.ml
 *  This program draws a wireframe model, which uses
 *  intensity (brightness) to give clues to distance.
 *  Fog is used to achieve this effect.
 *)

(* OCaml version by Florent Monnier *)

open GL
open Glu
open Glut

(* Initialize linear fog for depth cueing. *)
let myinit() =
  let fogColor = (0.0, 0.0, 0.0, 1.0) in

  glEnable GL_FOG;
  glFog (GL_FOG_MODE GL_LINEAR);
  glHint GL_FOG_HINT GL_NICEST;  (*  per pixel   *)
  glFog (GL_FOG_START 3.0);
  glFog (GL_FOG_END 5.0);
  glFog (GL_FOG_COLOR fogColor);
  glClearColor 0.0 0.0 0.0 1.0;

  glDepthFunc GL_LESS;
  glEnable GL_DEPTH_TEST;
  glShadeModel GL_FLAT;
;;

(* display() draws an icosahedron. *)
let display() =
  glClear[GL_COLOR_BUFFER_BIT; GL_DEPTH_BUFFER_BIT];
  glColor3 1.0 1.0 1.0;
  glutWireIcosahedron();
  glFlush();
;;

let reshape ~width:w ~height:h =
  glViewport 0 0 w h;
  glMatrixMode GL_PROJECTION;
  glLoadIdentity();
  gluPerspective 45.0 ((float w)/.(float h)) 3.0 5.0;
  glMatrixMode GL_MODELVIEW;
  glLoadIdentity();
  glTranslate 0.0 0.0 (-4.0);  (* move object into view *)
;;

let keyboard ~key ~x ~y =
  begin match key with
  | '\027' ->  (* Escape *)
      exit 0;
  | _ -> ()
  end;
  glutPostRedisplay();
;;

(* Main Loop *)
let () =
  ignore(glutInit Sys.argv);
  glutInitDisplayMode [GLUT_SINGLE; GLUT_RGB; GLUT_DEPTH];
  ignore(glutCreateWindow Sys.argv.(0));
  myinit();
  glutReshapeFunc ~reshape;
  glutDisplayFunc ~display;
  glutKeyboardFunc ~keyboard;
  glutMainLoop();
;;