GBAGI
The Sierra Adventure Game Interpreter for the Nintendo Game Boy Advance
By Brian Provinciano
Game Graphics and Visual Conversion
The original AGI games most commonly ran on PCs with 320x200 resolutions but
the Game Boy Advance only has a 240x160 pixel resolution. However, this causes
no real problem at all. The fact is that AGI only uses 160x168 pixels of graphical
screen space. Simply, the top and bottom four pixels can be cropped off, and
the image can be stretched from 160 to 240 pixels wide, which actually looks
much better than the most common PC versions, which stretched it from 160 to
320 pixels wide, and had all the empty space on the bottom of the screen.
Removing the bottom, non graphical space on the bottom of the screen is not
much of an issue because it was basically only used for text input. On some
platforms, such as the PC MDA/Hercules, as well as the Apple Macintosh versions
of AGI, it also cuts off the bottom area, and replaces the text input with
a pop
up
window
for the
player
to enter text (very much like GBAGI).
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The General PC Interface
Uses a 320x200 resolution with the play area stretched from 160 to
320 pixels wide in 16 colors and a text input area on the bottom with
empty space.
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The PC MDA/Hercules Interface
A 640x348 visible screen with the image dithered in monochrome, stretched
4x2, and central popup text input dialogs.
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The Apple Macintosh Interface
A 480x320 visible screen with the image dithered in monochrome stretched
3x2 and bottom popup text input dialogs. The top and bottom four pixels
of the 160x168 image are also cut off.
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The Game Boy Advance Interface
A 240x160 visible screen stretched to 1.5x1 with the image anti-aliased
to 256 possible colours and and central popup text input dialog.
The top
and bottom
four pixels
of the 160x168 image are cut off, but it is very minor, as this was even
done on the Macintosh port. Eight more of the top pixels are cut off
if the status bar is visible, but it is barely noticeable
and could toggled on/off.
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The Colors
Absolutely any colors desired can be used for the GBA version of
AGI. I chose to use a combination of the PC and Amiga palettes to produce
the best
look
for the games. The Amiga palette looks much better than the standard PC EGA
palette, as for example, the skin tones actually look more true to life.
The Screen Size
As stated above, the games use a 160x168 graphic resolution, and the GBA only
has a 160 pixel high screen. As a result, the top and bottom four pixels are
cut off. This it not an issue, as it was done on the Macintosh as well. When
the statusbar is visible, an additional eight pixels from the top are cut off,
but this is still not much of an issue. The status bar could be toggle on/off,
but this isn't necessary in my opinion. The reason is because the games generally
have a horizon set at roughly 40 pixels from the top, so the player would be
unable to walk past this point and would never be cut off. It would be very
easy to skip every 20 or so pixels to make it all visible, but I feel it looks
best with the top and bottom simply cropped off.
The Window Styles and Graphical User Interface
To give GBAGI a comfortable user experience, I built a graphical user interface
for the GBA. It acts very much like a scaled down version of Microsoft Windows
or another GUI. It includes windows, buttons, edit fields, listboxes, scrollbars,
bitmaps, and any other control can be added with ease. It runs optimally, and
only takes up CPU processing power when it's actually in use.
The graphical user interface can be customized to look any way desired. It
could be made to look like a MacOS, MacOS X, WindowsXP, GNOME, or any other
look up to your imagination. The colors can also be customized to any scheme.
Because the GUI system runs an event based messaging system, no CPU power
is wasted. It runs so fast on the GBA hardware that slowdown routines were
needed to be added!
The GUI works perfectly along with GBAGI, but is not tied to GBAGI. It can
be used as a stand alone GUI, or along side any other GBA game or program.
The games themselves can use the original style menus and dialog boxes as
were used on the PC, or like the Apple Macintosh and Apple IIgs versions, use
customized, more stylistic versions. Here are some examples:
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Original PC Style Dialogs
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