Darius,
Well the big main thing about glut, or sdl, or whatever bare bones framework used to create an OpenGL window are the following things:
1) Abstracting creating a window
2) Abstracting associating of a GL context with the widow
3) Abstracting the event loop
4) Abstracting reading mouse, keyboard, and terminate events
Regarding point #2, you really ought to consider allowing a specific context type, or profile, to be created, given core or es profile and a version.
In Free Glut this is done through:
glutInitContextVersion(4, 1);
glutInitContextProfile(GLUT_CORE_PROFILE);
With SDL this is done through:
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 2);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 0);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_ES);
Both of these are done in either API before the GL context is created. Essentially what they do is allow you the programmer to decide what type of context you are creating. In the case of the Free Glut example I am asking for an OpenGL 4.1 context. In the SDL example I am asking for an OpenGL ES 2.0 context.
These context profiles are important for a number of reasons. One reason is that they frequently determine which vendor dll (shared object on Mac and Linux) and implementation are dlls not only
require their own specific and distinct functions to load extensions, but they also operate differently. For example, the GLSL shader compiler on OpenGL 2.1 context may operate totally differently than the GLSL shader compiler on OpenGL 4.1.
Anyhow, the gist of all this is, you ought to provide the ability to allow the programmer ask for a profile, major and minor version. You ought to attempt to create the requested context type, load the API for the user based on the requested profile and version, and provide an abstracted stub that is filled out for properly to loading extensions for of the selected profiles and version.
Finally, you ought to detect when a profile failed to load, and gracefully fail when the context cannot be created. For example if the programmer requests OpenGL 4.1, and either the drivers for that version are not present, or the hardware doesn't Support 4.1, you should return 0 or nil when trying to create the context, and possibly have an error system so that the programmer can determine what went wrong. That is, an error message returns as a string with the words "The request context version 4.1 could not be created".
if Context = 0 then
begin
S := GLPT_GetLastError;
WriteLn(S)
Exit;
end;
Might result in this line written to the terminal:
The request context version 4.1 could not be created
