From: aaronstj AT aol DOT com (Aaron StJ)
Newsgroups: comp.os.msdos.djgpp
Subject: Tricks of the Game Programming Gurus -> DJGPP
Lines: 46
NNTP-Posting-Host: ladder03.news.aol.com
Date: 20 Sep 1998 07:23:51 GMT
Organization: AOL http://www.aol.com
Message-ID: <19980920032351.08728.00001580@ng-fc2.aol.com>
To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp
Precedence: bulk


Hello all,

     If you are familiar with (or at least have) Andre LaMothes book Tricks of
the Games Programming Gurua, please keep reading.  If not, you'll have a real
hard time following along.

     Me and my friend are working on a raycasting game (wolfenstein-style),
using code from Andre LaMothe's book Tricks of the game Programming Gurus, and
we're having problems getting the main raycasting code to work.  

     We've decided the easiest wayto convert the code to DJGPP was to take the
simple ray-cast program (ray.exe form chapter 6) and convert that, then work
from there.  Converting it was mainly changing a lot of _fmalloc's to malloc's,
and switching from the microsoft graphics library to to Allegro.

     The problem:  When a ray is cast verticall, the program goes boom (see the
error it gives me, postes at the end of this message)!  In LaMothe's code,
there is something to correct for asymptotes, but it doesn't seem to work as
comiled by gcc.  Any suggestions? (email if you want the source I came up with)

The error it gives me:

General Protection Fault at eip=00001f63
eax=0129e005 ebx=00000219 ecx=00000006 edx=0129dfff esi=00000054 edi=0003b824
ebp=0128df74 esp=0128def0 program=A:\RAY.EXE
cs: sel=00a7  base=82c3e000  limit=0129dfff
ds: sel=00af  base=82c3e000  limit=0129dfff
es: sel=00af  base=82c3e000  limit=0129dfff
fs: sel=00c7  base=00000000  limit=ffffffff
gs: sel=00c7  base=00000000  limit=ffffffff
ss: sel=00af  base=82c3e000  limit=0129dfff

Call frame traceback EIPs:
  0x00001f63
  0x000029f9
  0x00022bc2

.---------------------------------------------------------------.
| Aaron St.John - Atari 2600 Collector, djgpp newbie, pov-ray	|
| fan, man with the most boring .sig, etc.			|
`---------------------------------------------------------------'