AmiGTA v0.0.2

Put it anywhere. v0.0.1 hard-coded Work: into every path it opened, so
unless you unpacked into your Work: partition the game could not find its own
data — and the README told you to assign Work: to work around it. That was a
bug with a workaround printed next to it, and several people quite reasonably
asked what the "work directory" was supposed to be.

The game now finds everything through PROGDIR:, the drawer the program was
started from. There is nothing to assign. Unpack to DH1:Games/AmiGTA, a CF
card, wherever — cd there and execute run, or double-click an icon.

This archive contains no game data and nothing derived from it. You need your
own copy of Grand Theft Auto (1997) for the PC; two files from it go into the
GTADATA drawer that is already in the archive, and the bundled gtabake
converts the art on the Amiga. README.txt has the steps.

The collisions stopped jittering

Cars hit each other properly now. Four things were wrong and all four are fixed:

• The positional correction undid 100% of the overlap in one tick with no
  tolerance — the textbook oscillator. Now half of it, beyond a 1 px slop.
• The mass split was backwards. Each car moved by its own mass share instead
  of the other's, so a bus hitting a saloon was thrown backwards itself. That
  was the "my own car teleports" half of the complaint.
• The impulse fired every tick the boxes overlapped — one bus-into-saloon
  contact charged thirteen of them. It now fires once per contact, behind a
  latch, the way the original does it.
• A knocked car was cut off mid-slide by a timer and darted back into its lane.
  It now settles at rest and drifts back while it straightens up.

Measured, not eyeballed: a new REVERSALS counter reads 2/2 before and 0/0
after, with tunnelling still at zero and traffic flow unchanged at 88%.

No screen teardown at startup

The game used to close and reopen its screen twice immediately after the first
frame, as a self-test of the F3 title-bar path. That is now opt-in and off in
this archive. If you saw one frame and then a crash — on MorphOS or anywhere
else — this is the first thing to retry. It is an untested fix on those
systems: it removes the operation that sits exactly where the crash was
reported, but nobody has confirmed it there yet. Reports welcome.

What is in the archive

build	screen	backend
gta-aga	320x200	AGA
gta-rtg240	320x240	CyberGraphX / Picasso96
gta-rtg480	640x480	RTG, renders 320x240 and doubles it

Plus gtabake (the converter, runs on the Amiga), run, and README.txt.
On a non-AGA machine start with gta-rtg240.

You need: a 68020 or better — no FPU is required and none is used — about
8 MB of fast RAM, and a 1 MB stack, which run sets and the icons carry.

MIT, except the two chunky-to-planar kernels, which are © Mikael Kalms.

AmiGTA v0.0.1

First release. You can walk around Liberty City, steal a car and drive it.

This archive contains no game data and nothing derived from it. You need
your own copy of Grand Theft Auto (1997) for the PC. Two files from it —
style001.gry and nyc.cmp — go into the GTADATA drawer that is already in
the archive, and gtabake converts the art on the Amiga. Full step-by-step
instructions are in README.txt inside the archive.

What is in the archive

file	screen	backend
gta-aga	320x200	AGA. The reference build; every speed figure is measured with this one.
gta-rtg240	320x240	CyberGraphX / Picasso96. More of the city on screen.
gta-rtg480	640x480	RTG. Renders 320x240 and doubles it — a 68020 cannot rasterise 640x480 at a playable rate, so this way the picture is sharp rather than slow.
gtabake		The tile converter. Runs on the Amiga, on your own files.
run		Startup script. Its last line chooses which build starts.

All three read Work:backend.txt if it exists — one word, rtg, aga or
wb — which overrides the built-in default.

What you need

• 68020 or better. No FPU is required and none is used.
• AGA for gta-aga; a CyberGraphX or Picasso96 8-bit screen for the RTG builds.
• About 8 MB of fast RAM to play. The one-off conversion wants about 6 MB free.
• A 1 MB stack — the run script sets it, and the icons ask for it. It is not
  optional: libnix gives a CLI process 4 KB and the loaders go well past it.

Works

The city renders in 2.5D with the original's own projection and no gaps in the
geometry. You walk, run and turn; pedestrians walk about in varied clothing;
traffic drives itself along real routes, gives way, queues and takes corners as
an arc; you get in and out of cars and drag the driver out if there is one.

The driven car uses the original's own physics — mass, moment of inertia and
contact point are the game's own numbers, not values tuned by hand. Clip
another car on the corner and it rotates; ram it square and it slides. A light
car does not shove a tanker.

gta-aga runs at 59.8 fps on the project's calibration machine — a 68020 core
with the throttle standing in for a faster CPU, JIT off. That is a measurement
of one configuration, not a promise about your Amiga.

Not there yet

No missions, no weapons, no police, no wanted level. Sound is not wired up.
Tyre marks, blood and oil are not drawn. Liberty City only.

Licence

MIT, except the two chunky-to-planar kernels, which are © Mikael Kalms and keep
their own headers. Grand Theft Auto is © DMA Design / Take-Two Interactive;
this project is not affiliated with them and ships nothing of theirs.