Re: [Caml-list] ocaml+sdl+opengl ?

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

Le dimanche 11 avril 2010 19:53:29, Florent Monnier a écrit :
> 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.)

So I have made another test. I have copied the following files from the sources 
of ocamlsdl from its directory ocamlsdl-0.7.2/src/ into the same directory 
where are located the test files (which are at the end of this email):

common.c         sdlgl_stub.c        sdl.ml           sdlvideo_flag.c
common.h         sdlinit_flag.c      sdlmouse.ml      sdlvideo_flag.h
config.h         sdlinit_flag.h      sdlmouse_stub.c  sdlvideo.ml
files            sdljoystick.ml      sdlmouse_stub.h  sdlvideo_stub.c
sdlevent.ml      sdljoystick_stub.c  sdlrwops_stub.c  sdlvideo_stub.h
sdlevent_stub.c  sdlkey.ml           sdlrwops_stub.h
sdlgl.ml         sdlkey_stub.c       sdl_stub.c


Then I have compiled everything with :

ocamlopt -o test bigarray.cmxa \
  sdl.ml sdlmouse.ml sdljoystick.ml sdlkey.ml \
  sdlevent.ml sdlvideo.ml sdlgl.ml \
  $GL_BINDINGS test.ml \
  -ccopt "`sdl-config --cflags`" \
  sdl_stub.c sdlgl_stub.c sdlvideo_stub.c sdlkey_stub.c sdlevent_stub.c \
  sdlmouse_stub.c sdljoystick_stub.c common.c sdlrwops_stub.c \
  -cclib "-lGL `sdl-config --libs`"

where I switch the OpenGL bindings with:

GL_BINDINGS="-I +glMLite GL.cmxa"
GL_BINDINGS="-I +lablGL lablgl.cmxa"

here the results I get:

=> with LablGL it fails again.
=> with glMLite now it works in native code too.

Again the SDL part fails with one OpenGL bindings and not with the other one.
What could explain this ?

Also with glMLite and in native mode, using ocamlsdl as a lib fails, and 
compiling locally ocamlsdl's source files succeeds.
What could explain this ?


> ================================
> 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()
> ================================