As of 2016, these are generally considered obsolete, but were still important during the transition to hardware acceleration:
These libraries are designed explicitly to abstract 3D graphics hardware for CAD and video games, with possible software fallbacks.
"imagination shows off vullkan gains". http://www.bit-tech.net/news/hardware/2015/08/11/imagination-vulkan/1 ↩
"dreamcast development board". 25 August 2010.kamui manual, naomi board, DC https://forum.beyond3d.com/threads/dreamcast-development-board.49555/ ↩