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VIDEO - Experimental VGA patch (vgaonly commited)

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First post, by h-a-l-9000

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It emulates the video drawing as well as the palette and a few other things scanline by scanline. This is mostly needed by demo software but also by a few games. Some parts of it are hackish but the new output looks nice. The internal screenshot / video functions cannot capture it properly.

Build: http://home.arcor.de/h-a-l-9000/test/dosbox_demovga.zip

To enable, set machine=demovga in dosbox.conf.
It also adds the parameter ibmtiming under [dosbox] which might fix horizontal scrolling problems for certain games/demos (true/false).

Attachments

  • Filename
    demovga.diff
    File size
    24.73 KiB
    Downloads
    130 downloads
    File comment
    patch file
    File license
    Fair use/fair dealing exception
  • wcharts_split.png
    Filename
    wcharts_split.png
    File size
    66.07 KiB
    Views
    2932 views
    File comment
    The wcharts "diskmag" uses multiple palettes
    File license
    Fair use/fair dealing exception
  • panic_plasma.png
    Filename
    panic_plasma.png
    File size
    27.22 KiB
    Views
    2932 views
    File comment
    The panic demo makes the video display jump to different memory locations for each scanline
    File license
    Fair use/fair dealing exception
  • lemmings_split.png
    Filename
    lemmings_split.png
    File size
    36.22 KiB
    Views
    2932 views
    File comment
    Lemmings uses two palettes for this screen
    File license
    Fair use/fair dealing exception
  • dowhackado.png
    Filename
    dowhackado.png
    File size
    14.6 KiB
    Views
    2932 views
    File comment
    The dowhackado demo uses different palettes and suffers from a timer bug
    File license
    Fair use/fair dealing exception

Reply 1 of 90, by Kippesoep

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Very nice. Might be useful with CGA too (background colour, in particular). That would help tremendously with Frogger (which changes background colour to blue for the water part at the top of the screen).

My site: Ramblings on mostly tech stuff.

Reply 2 of 90, by wd

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Yep fine thing (though it looks a bit slow 😀 did you measure the impact)
and nice screenshots!
Kellogs comes to my mind, uses pel mask changing to draw some part
of the screen blue (water level).

Reply 3 of 90, by IIGS_User

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Yeah, I see. In previous versions of DOSBox, the sky always was dark blue. Now, in 0.70, ithe sky flickers between dark blue and blue.

Attachments

  • kell.png
    Filename
    kell.png
    File size
    15.31 KiB
    Views
    2902 views
    File comment
    Kellogg
    File license
    Fair use/fair dealing exception

Klimawandel.

Reply 4 of 90, by h-a-l-9000

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> Kellogs comes to my mind, uses pel mask changing to draw some part
> of the screen blue (water level).

That's why I brought it up recently 😉 can't get it to run.
Runtime error 002 at 0004:2C46.

The impact is not as much as I thought it would be. I can still play Terminal Velocity at ~27fps at fullscreen (normally ~30fps).

Frogger... I'll have a look if I find it.

I can add more screenshots if you like 😀

Reply 16 of 90, by augnober

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Nice work. I was thinking about this earlier (a little over a year ago, I guess) when I was making a patch to synchronize (/substitute) the internal emulation vertical refresh with the host display's vertical refresh (to remove shear, get smooth scrolling, etc. in certain apps). It would be interesting to try and get both of those changes to work together -- could lead to the feeling of a very real machine.

My patch didn't work out so well in the end. It worked great in Windows, but I wasn't able to find a reliable way to detect the retrace status in Linux.. and so I ended up dropping it after the workarounds for this got too complicated.