SDL_GL_GetProcAddress - Man Page

Defined in SDL3/SDL_video.h

#include "SDL3/SDL.h"

SDL_FunctionPointer SDL_GL_GetProcAddress(const char *proc);

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.

proc

the name of an OpenGL function.

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

This function should only be called on the main thread.

This function is available since SDL 3.2.0.

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

SDL_GL_LoadLibrary(3).