[Coco] AGD converted games

[Lee]

That's a project I would SO love to take on.  Unfortunately, I have a bad
habit of starting a project, then jumping to another before finishing.  So
I'm staying focused on my current project which is reverse engineering the
1985 Oregon Trail for the Apple II with the intention of porting/writing a
clone for the CoCo (or at least providing the results of my reverse
engineering to the community so someone else can do so if desired).

One idea that comes to mind for the AGD color port would be to keep the
data in a format where the pixel data and the attribute data are kept
separate and combined on the fly when drawn to the screen (the way I'm
assuming the ZX Spectrum hardware did).  Not sure of the performance impact
that might have though.

On Sat, Jun 15, 2019 at 3:36 AM Pere Serrat <psergm at gmail.com> wrote:

> You will find the number of colors question explained in my previous
> message.
>
> Concerning the port, specifically for the CoCo3 GIME I am sure it is doable
> despite it will imply a lot of changes to the AGD engine to deal with
> the colours.
> And even then we will need a 'special' graphics converter to create all
> objects
> with the graphic data info stored for say 320x200x8 using the ZX data
> that comes
> in bytes with pixels set for back-foreground and then looking fo the
> corresponding
> attribute byte for an area of 8x8 to calculate the CoCo3 correct bytes ...
>
> Right now, we are still working on some games that crashed while
> converting.
> There were 47 reluctant games and now there are only 14 still resisting
> hardly
> but we have already converted 182 AGD games.
> Next week I will be releasing two more packs.
>
> As soon as we close this project, I will try to analyze the changes that
> have to be
> done to the engine to have a global idea of the RAM mapping needed to have
> everything loaded from disk.
> One possible nightmare could be the attributes change. In ZX it is done
> with a
> single byte changed in the attributes area whereas in the CoCo3 it will
> imply
> some 128 bytes (16x16 pixels) or more if 16x24 pixels and bytes have to be
> calculated upon old colors to distinguish between back and foreground
>
> That said, if anyone wants to work on this port, I will give him the
> current engine
> source code and the RAM map I am using and of course I will try to be of
> help if
> any question arises along the project.
> In the source code I saved in the comments part the original Z80 code
>
> cheers
> pere
>
>
> ---------------------------------------------------------------------------------------------
> previous message
> > Message: 5
> > Date: Fri, 14 Jun 2019 19:17:52 -0400
> > From: Lee<leep at tigerbase.com>
> > To: CoCoList for Color Computer Enthusiasts<coco at maltedmedia.com>
> > Subject: [Coco] AGD converted games
> > Message-ID:
> >       <
> CANu-XmLnOay3n69-vMC1EywG0NC_nsUUMF_ahTsDNG6GGweiRg at mail.gmail.com>
> > Content-Type: text/plain; charset="UTF-8"
> >
> > First, let me say I think this project to port these games to the 6809 is
> > wonderful!  The work put into it deserves tremendous kudos!  Thank you to
> > any/all involved!    It seems like the original color of the games was
> not
> > able to be ported.  I say that because when I run them they appear to be
> > black-and-white with coincidental artifacting.  I'm using the
> Switch-A-Roo
> > cable and switching to RGB make it crystal sharp black-and-white.  I've
> > Googled videos of some of them on the ZX Spectrum and they are in color.
> > Is the reason they are in black-and-white because the image data or the
> > engine makes it difficult to retain the original colors when porting?  Or
> > is it not really possible?  If it is possible, would it be feasible (if
> > someone wanted to take it on) to start converting these to have their
> > original colors?
> >
> >
> > ------------------------------
>
>
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