Use of [ANSI] VDI routines for animation

[Ted A. Campbell]

I am using an AT&T Unix PC with the GSS Drivers for the ANSI 
VDI standard (similar to the GEM VDI utilized on Atari ST 
and other computers).  I am also attempting to develop a 
implementation of the VDI for the PCs, using Microsoft Quick C
(I refuse to pay $500 for the GEM development kit).  

I've written a mapping program that uses the MWDB data 
(Micro World DataBase) to draw the earth as seen from space 
with coastlines represented.  I can draw the planet in a number 
of different rotations.  But suppose I want to (try to) show 
the earth rotating on the screen?  My VDI documentation 
seems to have nothing on bit-blits under VDI, so how could
one simulate animation using the VDI line-drawing (and fill)
routines?  

Any suggestions will be apreciated.  

Ted A. Campbell
Duke Divinity School
{ethos, ecsgate}!dukeac!numen!tcamp