GREG is a code generator that produces an stb-style header-only OpenGL and OpenGL ES function loader library tailored to your needs. It is lovingly sculpted from a block of pure frustration with the large number of promising and yet ultimately unusable loader generators out there.
The primary sources of inspiration are flextGL and glad, in that order.
GREG is licensed under the
zlib/libpng license, which can be found
in the COPYING.md file. The license is also included at the top of the source
file.
GREG is not yet done. Go away. Shoo. Come back when it's done.
Compile and run greg to generate the desired greg.h header library. See
greg --help for details.
Include greg.h where needed. Define GREG_IMPLEMENTATION before inclusion in
exactly one compilation unit.
Get a current OpenGL or OpenGL ES context somehow. Call gregInit. If it
returns non-zero, you're done. If it returns zero something is broken and
you're out of luck.
GREG supports loading via native APIs on Windows, OS X and systems running X11,
and will auto-select the proper backend at compile-time. GREG also supports
loading via EGL, GLFW 3 and SDL 2 by defining GREG_USE_EGL, GREG_USE_GLFW3
or GREG_USE_SDL2, respectively.
GLELG (i.e. OpenGL Extension Loader Generator) sounds stupid, whereas GREG sounds stupid in a different way. If you want, you can pretend that GREG stands for オープンジーエルエクステンションジェネレータ. I do that sometimes.
Here is the Wikipedia page for lettuce.
Why is there no support for GLWT?
GLWT does not provide the functions needed to allow GREG to load through it, but GLWT will co-exist just fine with the native backends.
Here is the Wikipedia page for yarn.
GREG requires a C++11 compiler, which is probably what you're going to be compiling its output with anyway, CMake for generating project or make files, and comes already bundled with its remaining dependencies. These are:
- getopt_port for parsing command-line options
- pugixml for a wonderful little XML DOM with XPath
- wire for a usable replacement string class
The output of GREG requires only a C89 compiler and headers for the selected backend.
GREG has been successfully built with the following C++11 compilers:
- Clang 3.0 with libstdc++
- Visual C++ 12.0 (VS 2013)
- GCC 4.9.2 cygstdc++