gl_setcontextvga man page
gl_setcontextvga — set the context to the physical screen
int gl_setcontextvga(int mode);
Set the graphics context to the physical screen of a vga mode (as defined in vga_setmode(3)). The mode must be set with vga_setmode(3) prior to using any of the drawing functions. vgagl does not take care of that.
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.
In all of the svga modes this program makes a description of the vga mode available to the vgagl functions. The 256 color svgamodes are handled properly by this program.
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_line(3), gl_getcontext(3), gl_setcontext(3), gl_setcontextheight(3), gl_setcontextvgavirtual(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. This page was modified by Don Secrest <firstname.lastname@example.org>.
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_line(3), gl_setcontext(3), gl_setcontextvgavirtual(3), gl_setcontextvirtual(3), gl_setcontextwidth(3), vgagl(7).