Sign in to follow this  

OpenGL cross platform game dev questions

Recommended Posts

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. :)

Share this post

Link to post
Share on other sites
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?

Share this post

Link to post
Share on other sites
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).

Share this post

Link to post
Share on other sites
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.

Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Sign in to follow this  

  • Announcements

  • Forum Statistics

    • Total Topics
    • Total Posts
  • Similar Content

    • By test opty
      Hi all,
      I'm starting OpenGL using a tut on the Web. But at this point I would like to know the primitives needed for creating a window using OpenGL. So on Windows and using MS VS 2017, what is the simplest code required to render a window with the title of "First Rectangle", please?
    • By DejayHextrix
      Hi, New here. 
      I need some help. My fiance and I like to play this mobile game online that goes by real time. Her and I are always working but when we have free time we like to play this game. We don't always got time throughout the day to Queue Buildings, troops, Upgrades....etc.... 
      I was told to look into DLL Injection and OpenGL/DirectX Hooking. Is this true? Is this what I need to learn? 
      How do I read the Android files, or modify the files, or get the in-game tags/variables for the game I want? 
      Any assistance on this would be most appreciated. I been everywhere and seems no one knows or is to lazy to help me out. It would be nice to have assistance for once. I don't know what I need to learn. 
      So links of topics I need to learn within the comment section would be SOOOOO.....Helpful. Anything to just get me started. 
      Dejay Hextrix 
    • By mellinoe
      Hi all,
      First time poster here, although I've been reading posts here for quite a while. This place has been invaluable for learning graphics programming -- thanks for a great resource!
      Right now, I'm working on a graphics abstraction layer for .NET which supports D3D11, Vulkan, and OpenGL at the moment. I have implemented most of my planned features already, and things are working well. Some remaining features that I am planning are Compute Shaders, and some flavor of read-write shader resources. At the moment, my shaders can just get simple read-only access to a uniform (or constant) buffer, a texture, or a sampler. Unfortunately, I'm having a tough time grasping the distinctions between all of the different kinds of read-write resources that are available. In D3D alone, there seem to be 5 or 6 different kinds of resources with similar but different characteristics. On top of that, I get the impression that some of them are more or less "obsoleted" by the newer kinds, and don't have much of a place in modern code. There seem to be a few pivots:
      The data source/destination (buffer or texture) Read-write or read-only Structured or unstructured (?) Ordered vs unordered (?) These are just my observations based on a lot of MSDN and OpenGL doc reading. For my library, I'm not interested in exposing every possibility to the user -- just trying to find a good "middle-ground" that can be represented cleanly across API's which is good enough for common scenarios.
      Can anyone give a sort of "overview" of the different options, and perhaps compare/contrast the concepts between Direct3D, OpenGL, and Vulkan? I'd also be very interested in hearing how other folks have abstracted these concepts in their libraries.
    • By aejt
      I recently started getting into graphics programming (2nd try, first try was many years ago) and I'm working on a 3d rendering engine which I hope to be able to make a 3D game with sooner or later. I have plenty of C++ experience, but not a lot when it comes to graphics, and while it's definitely going much better this time, I'm having trouble figuring out how assets are usually handled by engines.
      I'm not having trouble with handling the GPU resources, but more so with how the resources should be defined and used in the system (materials, models, etc).
      This is my plan now, I've implemented most of it except for the XML parts and factories and those are the ones I'm not sure of at all:
      I have these classes:
      For GPU resources:
      Geometry: holds and manages everything needed to render a geometry: VAO, VBO, EBO. Texture: holds and manages a texture which is loaded into the GPU. Shader: holds and manages a shader which is loaded into the GPU. For assets relying on GPU resources:
      Material: holds a shader resource, multiple texture resources, as well as uniform settings. Mesh: holds a geometry and a material. Model: holds multiple meshes, possibly in a tree structure to more easily support skinning later on? For handling GPU resources:
      ResourceCache<T>: T can be any resource loaded into the GPU. It owns these resources and only hands out handles to them on request (currently string identifiers are used when requesting handles, but all resources are stored in a vector and each handle only contains resource's index in that vector) Resource<T>: The handles given out from ResourceCache. The handles are reference counted and to get the underlying resource you simply deference like with pointers (*handle).  
      And my plan is to define everything into these XML documents to abstract away files:
      Resources.xml for ref-counted GPU resources (geometry, shaders, textures) Resources are assigned names/ids and resource files, and possibly some attributes (what vertex attributes does this geometry have? what vertex attributes does this shader expect? what uniforms does this shader use? and so on) Are reference counted using ResourceCache<T> Assets.xml for assets using the GPU resources (materials, meshes, models) Assets are not reference counted, but they hold handles to ref-counted resources. References the resources defined in Resources.xml by names/ids. The XMLs are loaded into some structure in memory which is then used for loading the resources/assets using factory classes:
      Factory classes for resources:
      For example, a texture factory could contain the texture definitions from the XML containing data about textures in the game, as well as a cache containing all loaded textures. This means it has mappings from each name/id to a file and when asked to load a texture with a name/id, it can look up its path and use a "BinaryLoader" to either load the file and create the resource directly, or asynchronously load the file's data into a queue which then can be read from later to create the resources synchronously in the GL context. These factories only return handles.
      Factory classes for assets:
      Much like for resources, these classes contain the definitions for the assets they can load. For example, with the definition the MaterialFactory will know which shader, textures and possibly uniform a certain material has, and with the help of TextureFactory and ShaderFactory, it can retrieve handles to the resources it needs (Shader + Textures), setup itself from XML data (uniform values), and return a created instance of requested material. These factories return actual instances, not handles (but the instances contain handles).
      Is this a good or commonly used approach? Is this going to bite me in the ass later on? Are there other more preferable approaches? Is this outside of the scope of a 3d renderer and should be on the engine side? I'd love to receive and kind of advice or suggestions!
    • By nedondev
      I 'm learning how to create game by using opengl with c/c++ coding, so here is my fist game. In video description also have game contain in Dropbox. May be I will make it better in future.
  • Popular Now