VOGL is Valve's OpenGL tracer/debugger that they are backing for being of interest to game developers now that with the Source 2 engine Valve is fully backing OpenGL over Microsoft's Direct3D.
VOGL in fact is written against Linux to begin with rather than most debuggers being written for Windows and then ported to Linux after the fact. Valve has been developing VOGL mostly on Ubuntu-based distributions under Qt Creator. Their official compiler is LLVM's Clang but GCC also works at a slower speed. Valve developers have given much praise to Qt Creator during Steam Dev Days.
VOGL allows OpenGL tracing and debugging from OpenGL 1.x through OpenGL 3.3 for both core and compatibility contexts. OpenGL 4 support is being worked on but full GL4 support isn't expected until later in 2014.
Improvements to VOGL's trace editor user-interface is planned along with profiling and optimizing various functions. Longer-term the Valve developers want more UI improvements, on-the-fly tracing, faster logging, and vendor neutral debugging.
Many more details on Valve's VOGL OpenGL debugger can be found via this blog post by Valve's Rich Geldreich. It's a bit surprising that they didn't use or extend APITrace since back then when I was out at Valve HQ they were playing around with it, but instead have come up with a brand new OpenGL debugging solution for Linux.