Looking for example tsdl games

#1

I’ve been trying to get to grips with tsdl, and having a hard time of it. In particular, having to constantly unpack Result return values gets pretty clunky when following sdl tutorials (which assume an imperative API and typically only check the return value when doing things like creating a surface, not e.g. when changing the background colour).

I would love to see some examples of idiomatic tsdl code people have used in an actual game. (I’m also open to suggestions of other libraries if there are any; as far as I can tell the allegro and sfml bindings are dead and I couldn’t find any other options.)

#2

You can ignore (Sdl.fn args); or Sdl.fn args |> ignore; if you don’t want to handle the trivial error cases.

In practice the number of Sdl calls in code tends to be small, with abstractions, so the explicit ignore isn’t too onerous.

I think Tsdl is a good choice, or Tgls on top of that if you want to use OpenGL.

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#3

The rresult package provides two options:

  1. R.failwith_error_msg is a safer alternative to ignore, as it assures that inner result is used in a well-typed context, and ensures that an exception is raised as soon as something fails.
  2. Combine the results with the >>= and >>| operators. This is an elegant solution to avoid unhandled exceptions, but with the caveat during development that you don’t get a backtrace.
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#4

Hi,
ocaml-sfml is not completly dead, there is someone who took over the development in a fork.
It’s just easy to not see it since he developed it inside a branch.

I have another question toward Tsdl: did someone already made it work under Windows?

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#5

thanks, that’s good to know! i’ll give it a try and see.

#6

Also you need to know, although SFML is portable I was unable to make it work on Windows.
(This is why I’m using ocamlsdl2 now because it was easy to make it work on Windows)

#7

I have no idea but it seems to be in @fdopen’s OCaml for windows repository.

#8

Hi Daniel, I’m not sure but maybe you should add a main in the C stub, because there is this about SDL_main in the FAQWindows

You can see that in ocamlsdl2 in file sdlinit_stub.c at line 19 there is a C main() for this reason.

#9

I thought the main stuff was gone in sld2 (at least it is on macOS). But if that’s needed I suppose it’s still a cpp trick (and thus can’t be expressed via ctypes).

I can’t personally test this but if anyone’s willing to submit a windows only shim that is linked when tsdl is used on Windows® I’ll gladly merge it.

#10

I tryed to remove the main from ocamlsdl2 on Windows, then it still works in interpreted/bytecode (ocaml commmand), but compiled to native binary code I get the expected error:

undefined reference to `SDL_main'

So I bet opam-repository-mingw’s team probably just compiled the bindings, but probably didn’t run the tests.

You can/should probably add:

#include "SDL.h"
int main(int argc, char *argv[]) { }

to the file: src/tsdl_stubs.c

#11

I won’t try to install Tsdl on Windows because of the deps, but I can make a try on Linux, I added:

#include "SDL.h"
int main(int argc, char *argv[]) { }

to the file src/tsdl_stubs.c then the command:

ocamlfind ocamlc -g -thread -c src/tsdl_stubs.c

Should become:

ocamlfind ocamlc -g -thread -c -ccopt -I/usr/include/SDL2 src/tsdl_stubs.c

But I don’t know how to do this with ToPkg, so instead I replaced the include like:

#include "SDL2/SDL.h"

It works because my SDL2 include dir is not in a custom path, it’s just inside /usr/include.
(But for people who installed it in a custom path you should explain how to do.)

Also I just run the tests and adding an empty main is not enough, I had to add:

#include "SDL2/SDL.h"
int main(int argc, char *argv[]) {
    caml_main(argv);
    return 0;
}

Then it seems to work fine.