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*)

(*  bezmesh.ml
 *  This program renders a lighted, filled Bezier surface,
 *  using two-dimensional evaluators.
 *)

(* OCaml version by Florent Monnier
 *
 * This file was converted from C, the original file is available here:
 * http://www.opengl.org/resources/code/samples/redbook/bezmesh.c
 *)

open GL ;;
open Glu ;;
open Glut ;;

let ctrlpoints = [|
  [| [| -1.5; -1.5;  4.0; |];
     [| -0.5; -1.5;  2.0; |];
     [|  0.5; -1.5; -1.0; |];
     [|  1.5; -1.5;  2.0; |] |];
    
  [| [| -1.5; -0.5;  1.0; |];
     [| -0.5; -0.5;  3.0; |];
     [|  0.5; -0.5;  0.0; |];
     [|  1.5; -0.5; -1.0; |] |];
    
  [| [| -1.5;  0.5;  4.0; |];
     [| -0.5;  0.5;  0.0; |];
     [|  0.5;  0.5;  3.0; |];
     [|  1.5;  0.5;  4.0; |] |];
    
  [| [| -1.5;  1.5; -2.0; |];
     [| -0.5;  1.5; -2.0; |];
     [|  0.5;  1.5;  0.0; |];
     [|  1.5;  1.5; -1.0; |] |];
|]
;;


let initlights() =
  let ambient = (0.2, 0.2, 0.2, 1.0)
  and position = (0.0, 0.0, 2.0, 1.0)
  and mat_diffuse = (0.6, 0.6, 0.6, 1.0)
  and mat_specular = (1.0, 1.0, 1.0, 1.0)
  and mat_shininess = (50.0)
  in
  glEnable GL_LIGHTING;
  glEnable GL_LIGHT0;

  glLight (GL_LIGHT 0) (Light.GL_AMBIENT ambient);
  glLight (GL_LIGHT 0) (Light.GL_POSITION position);

  glMaterial GL_FRONT (Material.GL_DIFFUSE mat_diffuse);
  glMaterial GL_FRONT (Material.GL_SPECULAR mat_specular);
  glMaterial GL_FRONT (Material.GL_SHININESS mat_shininess);
;;


let display() =
  glClear[GL_COLOR_BUFFER_BIT; GL_DEPTH_BUFFER_BIT];
  glPushMatrix();
  glRotate  85.0  1.0  1.0  1.0;
  glEvalMesh2 EvalMesh2.GL_FILL 0 20  0 20;
  glPopMatrix();
  glFlush();
;;


let init() =
  glClearColor 0.0 0.0 0.0 0.0;
  glEnable GL_DEPTH_TEST;
  glMap2 Map2.GL_MAP2_VERTEX_3  0.0 1.0  3 4
          0.0 1.0  12 4  ctrlpoints;
  glEnable GL_MAP2_VERTEX_3;
  glEnable GL_AUTO_NORMAL;
  glMapGrid2 20  0.0 1.0  20  0.0 1.0;
  initlights();       (* for lighted version only *)
;;


let reshape ~width:w ~height:h =
  glViewport 0 0 w h;
  glMatrixMode GL_PROJECTION;
  glLoadIdentity();

  if w <= h then
    glOrtho (-4.0) (4.0)
            (-4.0 *. (float h) /. (float w))
            (4.0 *. (float h) /. (float w)) (-4.0) (4.0)
  else
    glOrtho (-4.0 *. (float w) /. (float h))
            (4.0 *. (float w) /. (float h)) (-4.0) (4.0) (-4.0) (4.0);

  glMatrixMode GL_MODELVIEW;
  glLoadIdentity();
;;


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


let () =
  ignore(glutInit Sys.argv);
  glutInitDisplayMode[GLUT_SINGLE; GLUT_RGB; GLUT_DEPTH];
  glutInitWindowSize 500 500;
  glutInitWindowPosition 100 100;
  ignore(glutCreateWindow Sys.argv.(0));
  init();
  glutReshapeFunc ~reshape;
  glutDisplayFunc ~display;
  glutKeyboardFunc ~keyboard;
  glutMainLoop();
;;