NAME

       SDL_GL_GetProcAddress - Get an OpenGL function by name.

SYNOPSIS

       #include <SDL3/SDL_video.h>

       SDL_FunctionPointer SDL_GL_GetProcAddress(const char *proc);

DESCRIPTION

       If the GL library is loaded at runtime with SDL_GL_LoadLibrary(), then all GL functions must be retrieved
       this way. Usually this is used to retrieve function pointers to OpenGL extensions.

       There  are  some quirks to looking up OpenGL functions that require some extra care from the application.
       If you code carefully, you can handle these quirks without any platform-specific code, though:

       • On Windows, function pointers are specific to the current GL context;  this  means  you  need  to  have
       created  a  GL  context and made it current before calling SDL_GL_GetProcAddress().  If you recreate your
       context or create a second context, you should assume that any existing function pointers aren't valid to
       use with it. This is (currently) a Windows-specific limitation, and in practice  lots  of  drivers  don't
       suffer  this  limitation, but it is still the way the wgl API is documented to work and you should expect
       crashes if you don't respect it. Store a copy of the function pointers that comes and goes  with  context
       lifespan.

       •  On  X11, function pointers returned by this function are valid for any context, and can even be looked
       up before a context is created at all. This means that, for at least some common OpenGL  implementations,
       if  you  look  up a function that doesn't exist, you'll get a non-NULL result that is _NOT_ safe to call.
       You must always make sure the function is actually available for a given GL context before calling it, by
       checking for the existence of the appropriate extension with  SDL_GL_ExtensionSupported(),  or  verifying
       that the version of OpenGL you're using offers the function as core functionality.

       •  Some  OpenGL  drivers, on all platforms, will return NULL if a function isn't supported, but you can't
       count on this behavior. Check for extensions you use, and if you get  a  NULL  anyway,  act  as  if  that
       extension  wasn't  available. This is probably a bug in the driver, but you can code defensively for this
       scenario anyhow.

       • Just because you're on Linux/Unix, don't assume you'll be  using  X11.  Next-gen  display  servers  are
       waiting to replace it, and may or may not make the same promises about function pointers.

       •  OpenGL function pointers must be declared APIENTRY as in the example code. This will ensure the proper
       calling convention is followed on platforms where this matters (Win32) thereby avoiding stack corruption.

FUNCTION PARAMETERS

       proc   the name of an OpenGL function.

RETURN VALUE

       Returns a pointer to the named OpenGL function. The returned pointer should be cast  to  the  appropriate
       function signature.

THREAD SAFETY

       This function should only be called on the main thread.

AVAILABILITY

       This function is available since SDL 3.2.0.

SEE ALSO

       SDL_GL_ExtensionSupported(3), SDL_GL_LoadLibrary(3), SDL_GL_UnloadLibrary(3)

Simple Directmedia Layer                           SDL 3.2.20                           SDL_GL_GetProcAddress(3)