From: "jakub" <marushka AT ozemail DOT com DOT au>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Sprite "ghost" help please.
Date: Tue, 21 Jul 1998 23:01:11 +1000
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References: <003801bdb49a$13b600a0$194e08c3 AT arthur>
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To: djgpp AT delorie DOT com
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Thanks for replying arthur, its driving me crazy. I've done some further
testing on the demo game, and posted another message mentioning the fps.

Arthur wrote in message <003801bdb49a$13b600a0$194e08c3 AT arthur>...
>>I've noticed that the allegro demo game has the same problem on my system.
>>I select page flipping mode, with a 640x480 screen.
>>
>>When you move your shift left-right, I can see two ships slightly appart,
>>like a ghost image on a bad tv set. It seems I am seeing the last position
>>of the ship sprite.


>
>Doen't happen to me. Which graphics card driver are you using? If you have
>an older graphics card, then you may not have the correct VESA drivers
>installed. I have no problems using VESA 1.x, both VESA 2.0 modes and the
>ATI Mach 64 driver (for my ATI Rage Pro Turbo card). I've gone over the
>source - there's no problems there. Try installing Display Doctor or UniVBE
>and see if the same happens.


I've just tried setting the Vesa2 modes in the demo game, and it tells me
VBE 2 not available. Vesa 1.x works though. But the flicker is still there
with page flipping.

I'm using a Graphic Blaster MA202. It's just a normal 2 meg card. As for the
driver, not sure if you are talking about the demo game driver, where I just
choose autodetect. Or the actual driver as used by windows, which is the one
that came from creative labs, their latest one for my card. I'm also running
this under win98, don't know if that makes any difference to the demo game.
I think I had the same 'flickering' problem with win95 and this demo.
.
>The TV ghost image you are on about does still happen, although much
reduced
>on a monitor. This is because the phosphor coating on the screen is still
>glowing from the last time the electron gun hits it when the new screen is
>redrawn. It's most noticable on the starfield. The way to get around that
is
>to use a fake motion blur between the points moved. You can see this in
>action in space games, such as I-War, where when you turn, the stars blur
>until you stop moving.


Yes, I know what you are saying. I've noticed this also. However this is
different from what is happening to the ship. I guess it 'flickers' but only
when you move side to side, going up (using thrust) the image is perfect,
same with its fire out the back, and the rocks, and bullets. This is the
same problem I am having with my little game I am trying to write, there the
bullet is super smooth, but the ship flickers when I move it.
The best result I could get as I posted in another message was using dirty
rectangles with the demo game. It was still a 'tiny' bit flickery but better
than double or page flipping.

cheers.
>James Arthur
>jaa AT arfa DOT clara DOT net
>