OpenGL support?

[pmarks-net]

I notice that libretro MAME includes vestigial support for OpenGL, but the retroogl.c file doesn't exist:

https://github.com/libretro/mame/blob/master/src/osd/libretro/libretro-internal/libretro.cpp#L68

Instead, the graphics are rendered in software here:

https://github.com/libretro/mame/blob/master/src/emu/rendersw.hxx

Is there a reason why OpenGL was never implemented? I want to run vector games like Asteroids, but MAME's software renderer looks awful compared to OpenGL, particularly when increasing the Beam Width and Beam Dot Size. Dots are drawn as vertical lines instead of circles:

Note that enabling the alternate renderer in RetroArch improves the resolution, but not the roundness.

Would it be more productive to use OpenGL, or to work on improving MAME's software renderer?