From: Nate Eldredge <neldredge AT hmc DOT edu>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: [OT] graphics routines
Date: 11 May 2001 18:48:37 -0700
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"Cody" <cody1 AT ktsnet DOT com> writes:

> How would I in DJGPP do the following:?  I have browsed the allegro game
> library but got nothing out of it (wayyyy too much code).  I can do the

If you use allegro, you can just call its functions, and don't need to
know how it works inside.  I found the manual and example programs
quite sufficient to figure out how to use it.

> following in 16-bit does apps, but DJGPP's 32-bit protected mode poses a
> problem.  Links to the code or just replies with the code would certainly be
> appreciated.
> 
> 1.  get into different video modes (320x200 w/ 256 colors and more, 320x240
> w/ 256 colors and more, 640x480 w/ 256 colors and more, etc.)?

__dpmi_int

> 2.  put a pixel in those modes (any difference in them...?)?

_farpokeb(_dos_ds, 0xa0000 + offset, color)

> 3.  get back into 80x25 text mode?

__dpmi_int

> I'm unfamiliar with at&t style asm (plus I'm <beginner at intel style asm),
> and even if I knew at&t style asm I wouldn't be able to do it since I think
> 32-bit protected mode getting into graphics are different than what I have
> to do with turbo c++.  I hope that the putpixel routine is the fastest that
> you know of, because that's the only one that really needs a lot of speed.

Actually, if your algorithm depends on putpixel being fast, it's in
trouble.  You should draw your image to a buffer somewhere and blit it
into video memory (dosmemput is helpful here).

-- 

Nate Eldredge
neldredge AT hmc DOT edu