2014-07-25 20:24:41 +00:00
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Apple2048
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==========
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This is an implementation of the game "2048" for the Apple // series. It
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requires an enhanced Apple //e, Apple //c or Apple //gs. The binary is a
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ProDOS system file.
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Instructions about how to play are displayed on launch. You can bring up the
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instructions at any time by pressing the 'h' key.
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2016-07-23 15:16:14 +00:00
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[Download a disk image](https://github.com/jeremysrand/apple2048/releases/download/v1.0.1/apple2048-boot.dsk)
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2014-07-25 20:24:41 +00:00
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Implementation Notes:
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=====================
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The game logic is in game.c and I believe it reproduces the basic behaviours of
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existing 2048 implementations. The code for animating tiles is mostly still
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written in C in anim.c and is messy. There are lots of opportunities to
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improve performance in animations.
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The way animations work is:
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* Text page one is copied to text page two.
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* Text page two is displayed.
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* The next frame is prepared on text page one.
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* Text page one is displayed
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* Repeat all of the above for the next frame.
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The copying of page one to page two is implemented in assembly. There is a
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problem with using text page two. The Apple //GS has a "bug" where shadowing
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of text page two from bank $00 to bank $E0 is not implemented. This lead to
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the creation of the "Alternate Display Mode" CDA which did this shadowing in
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software at a performance cost. Because I am using page two, early versions
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required "Alternate Display Mode" to be on.
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But, I worked around this in software. At startup, the code detects if it is
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running on a GS. If so, it choses to use a different implementation of the
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assembly routine to copy from page one to page two. This implementation
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switches to native 16-bit mode and does a copy from $000400 (text page one)
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to $E00800 (text page two) right into the $E0 bank. This avoids the need for
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shadowing $00 to $E0 and it now works as expected on a GS even with "Alternate
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Display Mode" off.
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Possible Improvements:
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======================
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* Make the animation code not suck so much.
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* Optimize the tile drawing code
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* Wait for the VBL interval before switching text pages to avoid any tearing.
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