Message-ID: <00df01bdb684$5dff6980$604d08c3@arthur>
Reply-To: "Arthur" <arfa AT clara DOT net>
From: "Arthur" <arfa AT clara DOT net>
To: "DJGPP Mailing List" <djgpp AT delorie DOT com>
Subject: Re: Sprite "ghost" help please.
Date: Thu, 23 Jul 1998 22:47:04 +0100
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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.


No problem.

>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.


Download and install UniVBE to get VESA 2.0. But if it still happens in VESA
1.x then it will still happen in VESA 2.0 (probably).

>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.


DJGPP is a DOS compiler and so really doesn't care what Windows drivers are
installed. You want the DOS ones. Autodetect should work fine, if it
actually displays a screen without crashing (ie it chooses the wrong
driver).

Win98 shouldn't make a difference, because AFAIK there's been no DOS update
since Win95.

[snip bit about phosphor coating on monitor]

>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.


Hmm. It's unusual for this to happen in all of the drawing modes. Try some
different resolutions, such as the VGA or ModeX resolutions. If these have
the same results, then it's probably not your graphics card.

The only thing I can think of then, is that you have some time consuming
program running in the background. I had a bit of a flickery experience when
I tried to run the game while running IE4. But it could be a timer problem.


James Arthur
jaa AT arfa DOT clara DOT net