int gl_setcontextvgavirtual(int mode);
Allocate a virtual screen in system memory identical to the graphics mode (as defined in vga_setmode(3)), and make that the current graphics context.
The function returns 0 for success and non-zero if the mode is not supported by the hardware.
The only thing you can do with a planar (mode X-like) 256 color mode is aligned gl_putbox, and use it as a target for gl_copyscreen.
svgalib(7), vgagl(7), svgalib.conf(5), threedkit(7), testgl(1), currentcontext(3), gl_allocatecontext(3), gl_copyboxfromcontext(3), gl_copyboxtocontext(3), gl_copyscreen(3), gl_freecontext(3), gl_getcontext(3), gl_setcontext(3), gl_setcontextheight(3), gl_setcontextvga(3), gl_setcontextvirtual(3), gl_setcontextwidth(3).
This manual page was edited by Michael Weller <email@example.com>. The exact source of the referenced demo as well as of the original documentation is unknown.
It is very likely that both are at least to some extent are due to Harm Hanemaayer <H.Hanemaayer@inter.nl.net>.
Occasionally this might be wrong. I hereby asked to be excused by the original author and will happily accept any additions or corrections to this first version of the svgalib manual.
gl_allocatecontext(3), gl_enablepageflipping(3), gl_freecontext(3), gl_getcontext(3), gl_setcontext(3), gl_setcontextvga(3), gl_setcontextvirtual(3), gl_setcontextwidth(3), vgagl(7).