From:	Joey Jojo Shabadoo <james AT manc DOT u-net DOT com>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Screen Offset register + Gravity Force
Date:	Wed, 10 Dec 1997 04:24:47 +0000
Organization:	Bacardi Ferrari V12
Lines:	33
Message-ID:	<348E198F.4CAE@manc.u-net.com>
NNTP-Posting-Host:	193.119.189.51
Mime-Version:	1.0
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

Hello fellow coders!
Anyone remember Gravity Force on the Amiga?  Well I sure do
and I'm trying to write a PC version, but seeing as how this
is early days of serious coding for me I've run into a few
hurdles, ie smooth scrolling.
I've sussed waiting for the vertical blank in machine code
(kind of!) but have probs with screen offsets and pages/double
buffering etc.  I know the screen is at 0xA0000 but what PORT is the
x/y offset for a particular page? (I know 0x13 -> 0x3D4, 0x3D5 is the
virtual page width but so far to no avail..)
Can anyone direct me to a FAQ that gives all the PORTs (like 0x417
for keyboard) and Interrupt calls available?  Please?!
Also I'm having trouble reading the joystick x/y so player 2
can only shoot & thrust so far.  Flying with the mouse works cool tho!

Well, to see how VIOLENTLY unoptimised I can write check out my
version of Gravity Force so far (+source).  You can fly (2 players)
and shoot.  Notice how the ships vanish near the top?  Double buffering
would sort that out but how do I do a fast bulk mem copy in C++?

http://www.manc.u-net.com/gforce.zip    [85k]

Probs with it, or help either here or email, cheers!

Jim

PS is it worth me the time of getting DJGPP?  Has it got an IDE?
I'd like the 32bit code bit but TurboC++ 3 DOS is OK for now?
-- 
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James Shaughnessy      Bacardi Ferrari V12  Ace Class     
james AT manc DOT u-net DOT com  http://www.manc.u-net.com/gp2.htm  
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