For about a year now, I've been working on a little cross-platform C++ library that would help put together 3D OpenGL games. I say a library, because I don't really want to make a game engine, I just want to keep common boilerplate code somewhere separate. I'm developing this library mainly for learning purposes, I do not intend to offer is as a actual game development library.
It all started when I bought two game programming related books - the Game Programming Gems and Game Coding Complete (3rd edition), which is an excellent and well-written book. The books gave me quite good understanding about what game programming is like and also provided many useful code snippets (such as the event system and hashed string from Game Coding Complete).
So far, I have managed to create a simple model viewer using my library. I've got OpenGL 3 functionality (I'm not using any fixed functionality... at least I try not to) as far as having a custom matrix stack, the renderer draw the scene into a frame buffer and display it on screen, I've just got diffuse and specular lighting working with GLSL shaders. I've also implemented a basic GUI system, which can draw images, buttons and text on screen and react to mouse input. There is also an in-game Quake-style console for sending commands to the application and a basic component based entity system that still needs a few quirks sorted out.
My library also supports Bitmap and TrueType fonts. I'm using the FreeType library for the TrueType fonts, and I'm just rendering the font glyphs to a texture during runtime (at initialization) to get pixel perfect fonts. If you are interested in the code, I might just make a post about it.
I'm currently only using a few 3rd party libraries including Boost, FreeType, GLEW, GLFW and GLM (which is an excellent math library by the way!). Probably some more libraries will be added later for sound and networking. At first I was using SDL for window creation and input polling, but then switched to GLFW, because it is more lightweight and more OpenGL oriented.
I've split the library into modules such as Core, Renderer, Input etc. so each module can be compiled into a separate DLL or linked statically to an executable (preferred way). I'm using Boost.Build as the build system, since I found it relatively easy to get started with. I might switch over to CMake at some point though, because it seems to be more popular and easier to use perhaps...
I will continue developing this library at least to a point where I can make a reasonable little 3D game with sound and networking... perhaps a pong sort of game. If you are also interested in game programing, I would definately recommend the books mentioned above and also theses sites: Game Development on StackExchange.com and GameDev.net.
Here are a few screenshots of the model viewer: