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romer

OpenGL cross platform game dev questions

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romer    323
Greetings y'all. A close friend of mine and I have been kicking around the idea of developing a game together over the past nine months or so. While we've done a few things here and there (he's done some concept art, I've done some prototyping and what not), we haven't done a whole lot of core game functionality. Originally this was going to be a Windows only game, done pretty much all in DirectX, but over the past few weeks I got to thinking otherwise. You see, the two of us don't know if this game will even make any sort of money, but we keep optimistic. In fact, I was hoping it'd eventually become something like shareware. So with that in mind, I decided I'd begin the design over from scratch, but this time keeping in mind that I want this game to be able to run at least on Windows and Mac platforms, and hopefully can reach Linux gamers out there. The game is really a simple top down 2Dish game, very similar to GTA2 style graphics. Input is primarily (pretty much exclusively) keyboard driven. Now that I've taken quite a bit of time explaining the situation, allow me to dive into my questions. I must first say, though, that this is really my first full-fledged game that I'm programming. I know some of you may think that I'm biting off way more than I can chew, but believe me, I'm a very ambitious person. If I want to get something done, I'll stick to it until the end, and developing this game is something I have wanted to get done for a while now. ;) Anyways, on to the questions. Because I want this to be a cross platform project, I've pretty much committed to using OpenGL for my graphics API (I want the buildings to have that 3D feel to them like in GTA2). Now I've started reading up on how to use OpenGL and what not by reading the Red Book, and it's all fairly simple reading so far, nothing I can't handle. But the thing that's been racking my brain is the whole basic window creation step. I know how to create the window in Windows, but obviously that won't work on Mac or Linux platforms. So this leads me to investigating further by searching the forums and the Net. Now I've read a lot about SDL, and have seen that many people here have recommended using SDL, especially when it comes to the initial window set up. I've also read you can directly utilize OpenGL while using SDL. I guess it'd be a no-brainer to ask if SDL is an excellent choice for cross-platform development? Are there any snags or gotchas I should watch out for if I decide going the SDL+OpenGL route? Also, and I know I probably should need to worry about this, but for curiousity's sake, what sorts of limitations are there when you use OpenGL through SDL? Are some features inaccessible? Is there any reason to be looking for alternatives to SDL? As far as audio is concerned, I planned on using OpenAL for a cross platform library to handle playing my sound and music (which will most likely be in *.ogg format). Is there any reason why this library shouldn't work with OpenGL+SDL, or can I expect it to work fairly seemlessly with it? And I guess lastly, any tips or words of advice or 'gotchas' anyone can offer? Like, any endian issues or any platform specific issues I need to watch out for, or anything you've learned from experience that you can part on? I'm sorry, I realize this was a long and somewhat discombobulated post, but I do appreciate and thank you all taking the time to read it and giving help you can offer. :)

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C-Junkie    1099
There's really no reason to use anything other than SDL when using OpenGL as your primary graphics API.

SDL will take care of window creation, and give you a generic Event mechanism. SDL_img will take care of loading all kinds of image formats (and google must have something on converting SDL_Surfaces to GL textures by now). SDL_mixer or OpenAL will take care of sound. SDL_net will take care of doing network access.

Did I miss anything?

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Raduprv    997
SDL is teh r0x.
Seriously, we use SDL for Eternal Lands, and it works GREAT.
However, SDL is not very good with the sound, so I suggest using OpenAL and OGG/Vorbis (if you want music).
You can also use sdl_net for network (if you need network).

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sicilianfire    122
well, porting opengl through sdl is an excellent choice. i'm starting to do it myself, more to avoid the travesty of using the winapi than crossplatform issues, but it is nice and simple. the only thing i've come across that you need to be aware of are several of the functions used in opengl that have been converted to sdl (such as SDL_GL_SwapBuffers()). however, they are few and far between, so there really should be no problem. however, since you asked, you can port opengl through several scripts (most notably, python), but you'd be porting opengl through a ported script (if you were writing in c++) which can be a pain. just fyi. anyway, good luck, and give word when you're done. sounds interesting.

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