Reason for Render Mode having no effect

[Sir Wilco of Laffer]

Hello,

I was wondering why the "Render mode" setting doesn't work on every game that supported different video modes.
For example King's Quest I (AGI) and Larry 2 (SCI). I used to play both of them on an XT with a hercules graphics card (without simcga or other stuff). So I set scummvm to Hercules green, but I get EGA.
What's the reason for that? I can run KQ I in CGA, but not Hercules. It's not just the color palette, that's wrong, when playing on Hercules, the AGI interpreter also didn't allow typing while walking, but instead opend a window like SCI does on other graphics cards.
I've seen Larry 2 screenshots in CGA and there's CGA drivers on the disks, too, but I can only get it to produce EGA in scummvm.
What's the technical reason for that limitation?

[eriktorbjorn]

I think that only the SCUMM engine implements Hercules rendering for some of the games at the moment. I haven't heard anything about anyone working on it for other game engines. I could be wrong, of course.

[MusicallyInspired]

It would be nice if it did work. SCI0 and SCI1.0 EGA games come with Hercules Monochrome drivers. The hard part is replicating the way the Sierra drivers worked, I expect. Same for the EGA640 dithering driver for SCI1.1 games.

[Sir Wilco of Laffer]

How exactly do AGI and SCI work, is there an EGA picture in the resource files and the interpreter has to do color conversions for different graphics cards or does the interpreted game code itself produce different outputs if requested and scummvm only needs to supply a frame buffer which behaves like EGA, CGA or Hercules?

[sev]

How exactly do AGI and SCI work, is there an EGA picture in the resource files and the interpreter has to do color conversions for different graphics cards or does the interpreted game code itself produce different outputs if requested and scummvm only needs to supply a frame buffer which behaves like EGA, CGA or Hercules?

Roughly speaking, the engine performs color conversion. And dithering schemes are different between the engines and even individual games. And currently it has been implemented only for SCUMM games. We just need to use GUI options to disable it for games which do not support it to decrease confusion.


Eugene