[Caml-list] ocaml+sdl+opengl ?

[Florent Monnier]

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()
================================

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[Daniel Bünzli]

You did not specify the platform but on osx 10.6.3 sdl+lablgl works.

More precisely

> sdl+LablGL in interpreted mode => Failure

Works but you need to make a custom toplevel (see ocamlsdl's readme about osx).

$ ocamlmktop -I +lablGL -I +sdl -custom -o ocamlsdl lablgl.cma
bigarray.cma sdl.cma
$ ./ocamlsdl -I +lablGL -I +sdl test.ml

> sdl+LablGL in native code => Failure

Works here with

$ ocamlopt -I +lablGL lablgl.cmxa bigarray.cmxa -I +sdl sdl.cmxa test.ml -o test

Best,

Daniel

[Florent Monnier]

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 ?

[Florent Monnier]

> You did not specify the platform but on osx 10.6.3 sdl+lablgl works.

I'm using Linux.
(and glMLite does work on MacOSX too)

> > sdl+LablGL in interpreted mode => Failure
>
> Works but you need to make a custom toplevel (see ocamlsdl's readme about
> osx).
>
> $ ocamlmktop -I +lablGL -I +sdl -custom -o ocamlsdl lablgl.cma
> bigarray.cma sdl.cma
> $ ./ocamlsdl -I +lablGL -I +sdl test.ml
>
> > sdl+LablGL in native code => Failure
>
> Works here with
>
> $ ocamlopt -I +lablGL lablgl.cmxa bigarray.cmxa -I +sdl sdl.cmxa test.ml -o
> test

OK, so I guess the problem is specific for Linux

--
Best,
Florent

[Florent Monnier]

> > OK, so I guess the problem is specific for Linux
>

> Well apparently not, I just tried on my netbook and sdl+lablgl works
> perfectly (both byte and native).
>
> > uname -a
>
> Linux minidip 2.6.31-20-generic #58-Ubuntu SMP Fri Mar 12 05:23:09 UTC
> 2010 i686 GNU/Linux

I use Mandriva-Linux.

I have the same problem with the official mandriva package of ocamlsdl,
and with ocamlsdl compiled from sources.
What could be the problem?