[Scummvm-devel] Contributing to ScummVM with an interpreter for Magnetic Scrolls?
Paul Gilbert
paulfgilbert at gmail.com
Wed May 1 08:53:21 CEST 2019
Thanks for information Torbjörn. It doesn't sound like the missing screen
elements are things I'd miss all that much. Though maybe some of it could
eventually be reintroduced as an option. Whilst Glk doesn't currently have
any "listbox" window types, I do have an already implemented listbox
control for my stalled Legend engine that could probably be adapted. And a
main menu implementation could be useful for Frotz v6 as well as the
Magnetic engine.
It will be nice if they do release the original versions alongside the
remastered versions. Being away from home, I'm not sure how many Magnetic
Scrolls games I have, if any.. comes from having too large a collection..
I'm sure Strangerke among others can empathize :), So if I don't have all
of them; it would be nice to eventually have a legitimate source to get any
missing ones.
Paul.
On Wed, May 1, 2019 at 4:00 PM Torbjörn Andersson <eriktorbjorn at telia.com>
wrote:
> From what I remember, the main feature not supported by the Magnetic
> interpreter is some of the "Magnetic Windows" interface (on-screen map,
> compass rose, separate windows for inventory and room objects, horribly
> cluttered windowing system, ... oh, sorry, that last thing isn't really
> a feature, is it?) used by Wonderland and the Magnetic Scrolls Collection.
>
> At least as long as the front end implements the necessary hooks for
> displaying static and animated pictures, etc. I'm not sure if it loads
> the original data files, or if they have to be specially prepared. (The
> files on my Magnetic Scrolls Collection CD certainly don't look like
> anything the emulator would recognize.)
>
> Also, it doesn't try to emulate the original look of the games with its
> animated menus and pull-down graphics. Which is a bit of a shame or,, in
> the case of the Magnetic Windows interface, a huge relief.
>
> When I asked [1] on the Strand Games forum (the company in the process
> of remastering the Magnetic Scrolls games, after the source code was
> recovered from a backup tape [2]) if they were planning on release the
> original versions as well, just for nostalgia, I got a reply from Hugh
> Steers referring me to Stefan Meier's "Magnetic Scrolls Memorial" for
> data files for the emulator.
>
> Since "Strand Games was started by Hugh Steers - a founding member and
> core developer of Magnetic Scrolls and Stefan Meier, curator of
> if-legends.org" and they claim to have the support of "several members
> of the original Magnetic Scrolls team" [3], I guess those files are
> kiiind-of officially endorsed...? It's probably worth asking them again
> later.
>
> [1] https://strandgames.com/community/discussion/65/the-original-versions
> [2]
> https://strandgames.com/blog/magnetic-scrolls-games-source-code-recovered
> [3] https://strandgames.com/about
>
> Torbjörn Andesson
>
> On 01/05/2019 05.10, Paul Gilbert wrote:
> > Hi Thomas,
> >
> > I'm not sure of the status of the Gargoyle Magnetic Scrolls sub-engine,
> > and I don't currently have any Magnetic Scrolls games handy to test it
> > on. But unless it's significantly lacking in support for the later games
> > that your own work adds support for, it'll likely prove easier to work
> > on converting it, I'm afraid. Since, after all, someone else has already
> > done the work of hooking it up to Glk as well. So it'll be easier to do
> > minimal work (relatively speaking) to hook it up to the ScummVM version
> > of the Glk layer. And then I can keep testing it as I properly objectify
> > everything to make sure I don't break anything along the way.
> >
> > Though I'll be unlikely to be spending much time beyond basic polishing
> > up of the sub-engine afterwards. So based on your experience with the
> > games & engine involved, there might be opportunities afterwards for you
> > to contribute if you're interested, and to do pull requests to improve
> > the functionality of the engine based on your work.
> >
> > Regards,
> >
> > Paul.
> >
> >
> > On Wed, May 1, 2019 at 2:55 AM dettus <dettus at dettus.net
> > <mailto:dettus at dettus.net>> wrote:
> >
> > Hello.
> >
> >
> > I must admit that I have not heard about Gargoyle or GLK before.
> >
> > Judging from the github repository, the Gargoyle engine for Magnetic
> > Scrolls is using the original magnetic interpreter from Niclas
> > Karlson. What he did was, as far as I know, reverse-engineer the C64
> > ports of the Magnetic Scrolls games in a painstaking process to make
> > them run on DOS. What I did was starting from scratch and using his
> > code as a reference. His code is probably more settled than mine.
> > Plus, I'd hate to step on somebody's toes who has already invested
> > copious amounts of time and energy into a project, so if you prefer
> > to use his code: Please, please do so!
> >
> > What I can offer you is an engine using a more modern coding style.
> > Even though it is C, I am sure that it can be integrated easily with
> > C++ projects. I have worked with projects that use both languages
> > and I am experienced in designing APIs for that.
> >
> >
> > Thus far, I have the following function pointers for callbacks:
> >
> >
> > typedef int (*cbLineAOutputChar)(void* context,char c,unsigned char
> > controlD2,unsigned char flag_headline);
> > typedef int (*cbLineAOutputString)(void* context,char*
> > string,unsigned char controlD2,unsigned char flag_headline);
> > typedef int (*cbLineAInputString)(void* context,int* len,char*
> string);
> > typedef int (*cbLineADrawPicture)(void* context,tPicture*
> > picture,int mode);
> > typedef int (*cbLineASaveGame)(void* context,char* filename,void*
> > ptr,int len);
> > typedef int (*cbLineALoadGame)(void* context,char* filename,void*
> > ptr,int len);
> >
> > As well as those API functions:
> >
> > // configuration functions
> > int lineA_getsize(int* size);
> > int lineA_init(void* hLineA,void* pSharedMem,int
> > *sharedmemsize,void* pMag,int magsize,void* pGfx,int gfxsize);
> > int lineA_getVersion(void* hLineA,int* version);
> > int lineA_setCBoutputChar(void* hLineA,cbLineAOutputChar pCB,void
> > *context);
> > int lineA_setCBoutputString(void* hLineA,cbLineAOutputString
> > pCB,void* context);
> > int lineA_setCBinputString(void* hLineA,cbLineAInputString pCB,void*
> > context);
> > int lineA_setCBDrawPicture(void* hLineA,cbLineADrawPicture pCB,void*
> > context);
> > int lineA_setCBSaveGame(void* hLineA,cbLineASaveGame pCB,void*
> context);
> > int lineA_setCBLoadGame(void* hLineA,cbLineALoadGame pCB,void*
> context);
> >
> >
> > You typically initialize the engine with pointers to the game
> > binaries, set the function pointers, and let it run. When it reaches
> > a point where an input is required, the engine generates a callback
> > and pauses until the callback returns.
> >
> >
> > Regarding pictues: They are also being rendered internally, and
> > another callback is triggered. An upper layer must draw it in
> > whatever way it deems appropriate. So, it does not really care where
> > it sits, or if it will even be displayed. The data format itself is
> > very basic, almost .xpm.
> >
> >
> > typedef struct _tPicture
> > {
> > unsigned int palette[16];
> > int height;
> > int width;
> > char pixels[65536];
> > } tPicture;
> >
> >
> > I am sure I can design an extra function for animations, such as
> this:
> >
> > typedef int (*cbLineADrawAnimation)(void* context,tPicture*
> > frames[],int mode,int framenum,int delay);
> >
> >
> >
> > Please let me know if this is of interested to you.
> >
> > Thomas
> >
> >
> >
> > On 4/30/19 2:20 AM, Paul Gilbert wrote:
> >> Hi guys,
> >>
> >> Thanks for the excellent summary of the current status, Filippos.
> >> As he said, I'm currently in the middle of working my way through
> >> converting all the Gargoyle engines to ScummVM, cleaning them up
> >> and making them conform to our coding requirements, as well as
> >> making them proper C++ classes. If you do decide to work on the
> >> Gargoyle sub-engine, please let me know.. I'll hold off working on
> >> it until after I've converted the remaining sub-engines. That'll
> >> give you plenty of time.. the TADS & Hugo sub-engines are big
> >> enough that that'll likely take me a while to finish converting :).
> >>
> >> If you have any questions about the Glk engine specifically, feel
> >> free to drop me a line. There's also the technical forums at
> >> intfiction.org <http://intfiction.org>. Though my schedule is a
> >> bit packed for the next few weeks, so if you do email, I may take
> >> a bit to get back to you.
> >>
> >> As far as music and animation goes, music at least should be easy,
> >> so long as it's a standard format ScummVM understands. Currently
> >> the engine supports raw sound, wav files, aiff, and mp3. As for
> >> graphics, that's somewhat straightforward as well, as long as the
> >> graphics can be segmented into completely separate windows than
> >> the text, and it looks like the Magnetic Scroll games do.. when
> >> you create windows in Glk, you can specify what portion of the
> >> screen each will use (for text vs graphics). I've had a lot of
> >> trouble with the Frotz sub-engine, but only because graphics and
> >> text can intermingle in the same windows, which Glk doesn't allow.
> >>
> >> Regards,
> >>
> >> Paul Gilbert (aka DreamMaster).
> >>
> >>
> >>
> >>
> >>
> >> On Mon, Apr 29, 2019 at 7:18 PM Filippos Karapetis
> >> <bluegr at gmail.com <mailto:bluegr at gmail.com>> wrote:
> >>
> >> Sorry, forgot to say that the glk engine in ScummVM can be
> >> found here:
> >> https://github.com/scummvm/scummvm/tree/master/engines/glk
> >>
> >> There are currently subengines for the alan2, frotz, glulxe,
> >> magnetic, scott, and tads interpreters, in various stages of
> >> development. dreammaster is mainly working on these. You can
> >> also find information about the glk engine in our wiki:
> >> https://wiki.scummvm.org/index.php?title=ScummGlk
> >>
> >> Regards
> >> Filippos Karapetis
> >>
> >> On Mon, Apr 29, 2019 at 12:14 PM Filippos Karapetis
> >> <bluegr at gmail.com <mailto:bluegr at gmail.com>> wrote:
> >>
> >> Hello, and glad to hear about your interest in ScummVM,
> >> and your work on the Magnetic Scrolls games!
> >>
> >> It's great that you are working on this. Bear in mind,
> >> though, that there has been extensive work on the Magnetic
> >> Scrolls games, which has been integrated into the Gargoyle
> >> interpreter:
> >> http://ccxvii.net/gargoyle/
> >>
> >> Gargoyle is being integrated as a subengine into ScummVM,
> >> in the glk engine. The glk engine is a port of the
> >> Gargoyle engine into ScummVM. There's an extensive wiki
> >> for Gargoyle, here:
> >> http://ifwiki.org/index.php/Gargoyle
> >>
> >> So, my advice would be to make your engine part of the glk
> >> engine, and base your work on the already working Magnetic
> >> Scrolls interpreter from the Gargoyle engine. The
> >> interpreter is open source, and can be found here:
> >> https://github.com/garglk/garglk/tree/master/terps/magnetic
> >>
> >> The list of supported Magnetic Scrolls games can be found
> >> here:
> >>
> https://github.com/garglk/garglk/blob/master/terps/magnetic/Generic/games.txt
> >>
> >> And there's an archive about interactive fiction games,
> >> where a lot of resources about the Magnetic Scrolls games
> >> can be found, here:
> >>
> http://www.ifarchive.org/indexes/if-archive/magnetic-scrolls/
> >>
> >> Thanks for your interest in these games! It would be great
> >> to see your work on them :)
> >>
> >> Regards
> >> Filippos Karapetis
> >>
> >>
> >> On Mon, Apr 29, 2019 at 10:08 AM dettus <dettus at dettus.net
> >> <mailto:dettus at dettus.net>> wrote:
> >>
> >> Hello.
> >>
> >>
> >> My name is Thomas, I am a big fan of ScummVM.
> >>
> >> Currently, I am in the process of writing an
> >> interpreter for classic
> >> text adventures from Magnetic Scrolls, such as "The
> >> Pawn" or "The Guild
> >> Of Thieves".
> >>
> >> Even though I am not saying that it SHOULD be
> >> integrated into ScummVM, I
> >> would like to think that it COULD. It is WAY to early
> >> to really start
> >> integrating it, but I like to be prepared.
> >>
> >>
> >>
> >> So, the reason why I am writing this mail is because I
> >> would be
> >> interested as on how I would have to design my code to
> >> make it possible.
> >> Currently, my interpreter needs a couple of hooks into
> >> any form of GUI:
> >>
> >> - Initialization, where pointers to the original
> >> binaries are being provided
> >>
> >> - Callbacks for textual input (strings)
> >> - Callbacks for textual output (strings)
> >> - Callbacks for textual output (characters)
> >> - Callbacks for drawing a picture (XPM)
> >>
> >> My code is purely C, so callbacks I am using function
> >> pointers. Said
> >> functions are, at the moment, doing nothing more than
> >> just a simple
> >> printf() and fgets(). The games I can play so far are
> >> "The Pawn", "The
> >> Guild of Thieves" and "Jinxter". HOWEVER, later games,
> >> such as
> >> "Corruption", "Myth", "Fish!" and "Wonderland" added
> >> features such as
> >> animation and music.
> >>
> >> SO MY QUESTION is this: How would I best design the
> >> callbacks for
> >> animation and music in way so that it MIGHT be
> >> integratable into ScummVM?
> >>
> >>
> >>
> >> Dettus
> >>
> >>
> >>
> >> P.S.: My interpreter is available at
> >> http://www.dettus.net/dMagnetic.
> >>
> >> (Hopefully this link, and the fact that this is my
> >> first email will not
> >> make this spam. ;) )
> >>
> >>
> >>
> >>
> >>
> >> _______________________________________________
> >> Scummvm-devel mailing list
> >> Scummvm-devel at lists.scummvm.org
> >> <mailto:Scummvm-devel at lists.scummvm.org>
> >> https://lists.scummvm.org/listinfo/scummvm-devel
> >>
> >>
> >>
> >> --
> >> "Experience is the name every one gives to their mistakes"
> >> - Oscar Wilde
> >>
> >>
> >>
> >> --
> >> "Experience is the name every one gives to their mistakes" -
> >> Oscar Wilde
> >> _______________________________________________
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> >> Scummvm-devel at lists.scummvm.org
> >> <mailto:Scummvm-devel at lists.scummvm.org>
> >> https://lists.scummvm.org/listinfo/scummvm-devel
> >>
> >>
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