Graphics Mode - Render Mode

General chat related to ScummVM, adventure gaming, and so on.

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Simara
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Graphics Mode - Render Mode

Post by Simara » Mon Oct 31, 2005 6:55 pm

I have been a Scummvm user for some time, and I never got to understand the different Graphics Modes or Renders modes available.

Is there detailed end user documentation around witch ones are better, or could you guys recommend the better ones?

Thanks for your time, for a great Scummvm release, and the great work of the ports.

Kind regards,

Simara

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sev
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Post by sev » Mon Oct 31, 2005 8:55 pm

It's just a matter of taste, so no recommendations here. Though our screenshots gallery was made with HQ2x mode turned on in most cases. Some other run AdvMame2x and I personally run plain 2x ;).


Eugene

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Post by rebelscumm » Mon Oct 31, 2005 10:40 pm

I run 2x also. Anything higher for me crashes some games...

domino
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Post by domino » Tue Nov 01, 2005 1:01 pm

is there a way to run scummvm in opengl or overlay mode like it is in dosbox?

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sev
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Post by sev » Tue Nov 01, 2005 2:09 pm

We had OpenGL backend in the past, but deprecated it due to (a) it was not maintained (b) we had those scalers.


Eugene

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eriktorbjorn
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Post by eriktorbjorn » Tue Nov 01, 2005 2:51 pm

domino wrote:is there a way to run scummvm in opengl or overlay mode like it is in dosbox?
There used to be an OpenGL backend for ScummVM, but as far as I know the only benefit was an extra (and most would say pretty mediocre) 2x scaler. It wasn't noticeably faster, at least not for me, and since no one wanted to maintain it, it was removed. I think the only thing that remains of it these days is that we have a file called sdl-common.h.

Yossarian
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Post by Yossarian » Mon Apr 17, 2006 4:27 am

Can anyone explain what the render modes do? There doesn't seem to be anything about them in the documentation, or anywhere else for that matter.

Thanks.

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eriktorbjorn
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Post by eriktorbjorn » Mon Apr 17, 2006 7:32 am

Yossarian wrote:Can anyone explain what the render modes do? There doesn't seem to be anything about them in the documentation, or anywhere else for that matter.
From what I understand, render modes are used to simulate CGA (4-colour), Hercules (hi-res monochrome) or Amiga (16-colours, but slightly different palette than EGA) graphics.

Though it appears to be limited to the 16-colour games, and even then the really old (v1) versions of Maniac Mansion and Zak McKracken don't support it, as far as I can tell.

Yossarian
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Post by Yossarian » Mon Apr 17, 2006 6:43 pm

Okay, thanks for that. Now I can stop switching them on and off and squinting at the opening to Monkey Island to see if it looks any different.

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Post by eriktorbjorn » Mon Apr 17, 2006 9:31 pm

Yossarian wrote:Okay, thanks for that. Now I can stop switching them on and off and squinting at the opening to Monkey Island to see if it looks any different.
For the games where the option is supported, you shouldn't have to squint:

Maniac Mansion (v2), EGA (default)
Maniac Mansion (v2), CGA
Maniac Mansion (v2), Hercules (green)
Maniac Mansion (v2), Hercules (amber)

Yossarian
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Post by Yossarian » Mon Apr 17, 2006 9:35 pm

Thank you, I'll check it out when I track down a copy of MM

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eriktorbjorn
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Post by eriktorbjorn » Mon Apr 17, 2006 10:47 pm

Yossarian wrote:Thank you, I'll check it out when I track down a copy of MM
That's not the only game where it's supported, though. I just used it as an example. As I said, most 16-colour games (and demos) would be affected, at least by CGA mode, if I understand it correctly.

clem
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Post by clem » Mon Apr 17, 2006 11:05 pm

just curious, was the screen wider on those computers than on the then-PC's 4:3? Or should those screens be stretched to a 4:3 ratio?

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Post by cappuchok » Tue Apr 18, 2006 12:01 pm

clem wrote:just curious, was the screen wider on those computers than on the then-PC's 4:3? Or should those screens be stretched to a 4:3 ratio?
While I'm not any kind of authority on video modes, I believe that it should be stretched to a 4:3 ratio. Although 640x256 seems to be a very strange mode since a doubling of the lines would give a 1,25:1 ratio rather than a 1,33:1 as is traditional.

My best guess would be that the 640x256 screens shown above were not the entire screens. Most likely, the remaining 144 pixels were used for dialogue (above the scene viewport) and controls and inventory (below the viewport) taking the game up to 640x400. Then ScummVM needs to scale up to 640x480 to show the game correctly on a PAR 1:1 display just like with all other LucasArts games which ran a 320x200 or 640x400 resolution on a 4:3 display (thus requring a slightly non-square PAR back then).

Then again, just my 2 cents.

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LogicDeLuxe
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Post by LogicDeLuxe » Tue Apr 18, 2006 8:32 pm

Back then Pixels rarely were square, since old video hardware often was based on TV timing.
And even today, all DVD and DVB standard PAL and NTSC resolutions don't have sqare pixels. This is also true for C64, Amiga and all those game consoles.
If you really need the exact AR of all those devices and there video modes, you need to know the exact pixel clock und how the modes work (how many overscan and blank interval pixels, interlace or progressive, PAL or NTSC timing).
For example, MM and ZAK graphic have a different AR on C64 and Amiga. The number of lines is the same for both systems, but the Amiga has a slightly wider image, ie. C64 displays it with roughly 8 Mhz pixel clock while the Amiga does a roughly 7 MHz pixel clock (in that particular mode). Both systems display the same games with another different AR between PAL and NTSC as well, which is a difference of 100 lines (per frame) while the pixel clock changes only slightly.
VGA graphics is a bit easier to understand, as its not the timing there. It's just that all standard VGA resolutions are considered 4:3, no matter how may pixels there are.

A resolution of 640x256 is probably progressive PAL, which could have a 13.5 MHz pixel clock, like DVD players have, which would result in a native 702x288 resolution including the overscan area. Thus 640x256 would be close to 4:3.

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