ocaml+sdl+opengl ?

[Florent Monnier <monnier.florent@gmail.com>]

Hi,
I'm trying to use ocamlsdl for the windowing of an OpenGL application.

You will find below 2 test files, one using LablGL and one using glMLite.

I have made these test:

sdl+glMLite in interpreted mode => OK, everything works all right
sdl+LablGL in interpreted mode => Failure
sdl+glMLite in native code => Failure
sdl+LablGL in native code => Failure

The exception is raised by the function Sdlvideo.set_video_mode which is a 
function from ocamlsdl, so it is very strange that changing the OpenGL 
bindings changes the behaviour!

Here are respectively the commands I use:

ocaml -I +glMLite GL.cma bigarray.cma -I +sdl sdl.cma test.ml
ocaml -I +lablGL lablgl.cma bigarray.cma -I +sdl sdl.cma test.ml 
ocamlopt -I +glMLite GL.cmxa bigarray.cmxa -I +sdl sdl.cmxa test.ml -o test
ocamlopt -I +lablGL lablgl.cmxa bigarray.cmxa -I +sdl sdl.cmxa test.ml -o test


Does someone have an idea or a clue about how to fix the problem?
(The code is right, otherwise the first test wouldn't work.
Also the exact equivalent in pure C does work right.)

================================
let display() =
  GlClear.clear [`color];
  GlDraw.begins `triangles;
  GlDraw.color (0.0, 1.0, 0.0);
  GlDraw.vertex2 (-0.5, -0.5);
  GlDraw.vertex2 ( 0.0,  0.5);
  GlDraw.vertex2  (0.5, -0.5);
  GlDraw.ends();
  Sdlgl.swap_buffers()

let () =
  Sdl.init [`EVERYTHING];
  let _ = Sdlvideo.set_video_mode ~w:640 ~h:480 ~bpp:0 [`OPENGL; `DOUBLEBUF] 
in
  let rec loop() =
    match Sdlevent.poll() with
    | Some Sdlevent.KEYDOWN { Sdlevent.keysym = Sdlkey.KEY_ESCAPE }
    | Some Sdlevent.QUIT -> ()
    | _ -> display(); loop()
  in
  loop();
  Sdl.quit()
================================
open GL
let display() =
  glClear [GL_COLOR_BUFFER_BIT];
  glBegin GL_TRIANGLES;
  glColor3 0.0 1.0 0.0;
  glVertex2 (-0.5) (-0.5);
  glVertex2 ( 0.0) ( 0.5);
  glVertex2 ( 0.5) (-0.5);
  glEnd();
  Sdlgl.swap_buffers()

let () =
  Sdl.init [`EVERYTHING];
  let _ = Sdlvideo.set_video_mode ~w:640 ~h:480 ~bpp:0 [`OPENGL; `DOUBLEBUF] 
in
  let rec loop() =
    match Sdlevent.poll() with
    | Some Sdlevent.KEYDOWN { Sdlevent.keysym = Sdlkey.KEY_ESCAPE }
    | Some Sdlevent.QUIT -> ()
    | _ -> display(); loop()
  in
  loop();
  Sdl.quit()
================================