Relative slowdown compared to GLEW:
Each function gets called 10^7 times in a tight loop. Execution time of the loop gets measured.
This got executed on windows 8.1 with an intel i5 and an intel hd 4400 video card.
Julia 0.4 has been used, the C++ version was compiled with VS13 and for python the anaconda distribution with Python 2.7 was used.
The OpenGL function loader from ModernGL has undergone some changes over the time.
Starting with a very simple solution, there have been pull requests to include better methods for the function loading.
The current approach in ModernGL master was not written by myself, but by the Github user aaalexandrov.
Before aaalexandrov’s approach, the fastest approach would have used a pretty new Julia feature, named staged functions.
It should in principle yield the best performance as it compiles a specialized version of the function when it gets called for the first time. This is perfect for OpenGL function loading, as the pointer to the function can only be queried after an OpenGL context has been created. When the staged function gets called the pointer can be queried and gets inlined into the just in time compiled function.
Staged functions only work with the newest Julia build, which is why aaalexandrov’s approach is favorable.
ModernGL seems to do pretty well compared to C++ and python does very badly, with being up to 470 times slower in the case of glClearColor.
Julia in contrast offers nearly the same speed as calling OpenGL functions from C++ as can be seen in the table.
As all the OpenGL wrappers are pretty mature by now and bind to the same C library (the video driver), this should mainly be a C function call benchmark.
Python performs badly here, but it must be noted that there are a lot of different Python distributions and some promise to have better C interoperability.
As this benchmarks goal is to show that Julia’s ccall interface is comparable to a c function call from inside C++, the python options have not been researched that thoroughly.
From this benchmark can be concluded, that Julia offers a solid basis for an OpenGL wrapper library.
The code and results can be found on github