Claude
a31c2e49cc
Decoded from SKIDMARKS_CD32: - Computer drivers: the path of nodes laid 2 game units apart along the middle of the road, with side points 1 unit in from each wall. Drivers aim four nodes past where they'll be in four frames, or cut to the other side two nodes on at 70% throttle when running wide. Replaces the pure-pursuit AI; laps are quicker on every track. - Collisions: six points on the player's car (corners and sides, from .set words 6 and 7, now known to be half-length and half-width) are tested against the other car's box. Hits push the cars apart with a strength that grows with their speed difference, and spin the car. As in the original, only human players' cars collide; cars at different heights don't. - Towing: the hitch is at the car's back, the caravan sits 0.656 units behind it, and past 90 degrees both car and caravan bend back. The reconstructed collision weight (`mass`) is gone; old asset files with it still load.
6.5 KiB
Skids: a Super Skidmarks revival
A cross-platform (Windows, macOS, Linux) engine written in Rust that plays Super Skidmarks (Acid Software, 1995) on the original Amiga data.
The game's data was converted from the six original ADF disk images into
editable files in assets/. The images themselves
aren't kept in this repository.
- Each track: a 16-colour PNG (the PNG's palette is the track's palette), plus a text file with the lap gates and height map.
- Each car: a PNG sprite sheet and menu picture, plus a text file with its name, driver and handling.
- Sounds: WAV files.
- Music: the tune, as an OctaMED module.
- Pictures: the title picture and a few other images, as PNGs.
Edit them with any image editor or text editor. The build embeds the
assets/ folder, so the finished program is a single self-contained file.
The engine can still read the original disks directly: ADF images, the LHA
archives on them, and their CrunchMania-packed files.
skids extract --data <adfs> regenerates assets/ from them.
Because the binary and assets/ carry the original game data, anyone you
give either to also gets the game data.
What works
- All 24 tracks across the four track files, in their original palettes. Each has its isometric height map and lap gates, and walls along the road edges, curved the way the original curves them.
- All 9 cars (Mini, Beetle, Porsche, Formula 1, Midget, Truck, Police, Cow, Camaro) with their drivers' names, each with 32 headings and 25 body-tilt frames for hills.
- The original handling: each car drives with the values from its
.setfile, decoded from the executable, with separate profiles for human and computer drivers. The menu's Handling option also offers the original's six presets (Classic, Grunty, Zippy, Rippy, Slippery and Pedal Car). - The caravan: turn on Caravans in the menu and every car tows one.
- The original sound effects, and the original tune played by a built-in OctaMED player. The menu has a Music option: menus, always, or off.
- The original title picture.
- 1 or 2 players (split screen) plus up to 7 computer drivers.
- Power-slides, jumps, hills that slow you going up and speed you up coming down, spinning bumps against other cars, and skid marks burnt into the track.
- Lap and position tracking, lap times, and a results table.
- Engine note pitched with revs, tyre screech, crashes, backfires, a horn and start beeps, all from the original samples.
What's from the original, and what isn't
The game logic is a compiled Blitz Basic 2 program on disk 1. These parts were decoded from its machine code and work the same way here:
- the car physics: engine, grip, steering, gravity and jumps, and hills
- the meaning of every
.setvalue, and the handling presets - the walls along the road edges
- how the world is projected onto the screen, including height
- the computer drivers' path and how they choose their target and throttle
- collisions between cars. As in the original, only human players' cars collide: computer cars pass through each other and through caravans.
- towing, including caravans jack-knifing
The rest is new code written to feel like the original:
- lap counting
- the rescue of stuck cars (the original warps them back instead)
docs/FORMATS.md covers everything reverse engineered so far.
Running
cargo run --release
The built executable (target/release/skids, or skids.exe on Windows)
runs on its own from anywhere.
--data DIR adds to or overrides the built-in data. DIR can be an
assets folder, which lets you try edits without rebuilding:
skids --data assets. It can also be the original ADF images or LHA
archives. Without --data, a folder like that in the current directory or
next to the executable is picked up automatically. When a track or car
exists both as an asset and on disk, the asset wins.
| Action | Player 1 | Player 2 |
|---|---|---|
| Accelerate | ↑ (or W in one-player games) | W |
| Brake / reverse | ↓ (or S) | S |
| Steer | ← → (or A D) | A D |
| Horn | Right Shift | Left Shift |
| Pause | P | |
| Leave race | Esc |
Options: --scale 1|2|4 (window size), --mute.
Tools
skids info --data DIR # list tracks and vehicles found
skids extract --data ADFS [--out assets] # convert original disks into editable assets
skids bench --data DIR --seconds 120 # race CPU cars on every track: laps and time on road
skids trace --data DIR --track 11 --out t.png # plot walls, gates and CPU racing lines
skids render --data DIR --track 3 --out shot.png # headless screenshot
skids music --out tune.wav --seconds 60 # render the tune to WAV
skids unpack disk.adf --out files/ # extract a disk or LHA archive as-is
Building
You need a stable Rust toolchain.
- Linux: install the ALSA and X11 development packages, e.g.
sudo apt install libasound2-dev libx11-dev libxkbcommon-dev. To build without sound (no ALSA needed), usecargo build --release --no-default-features --features embed. - macOS / Windows:
cargo build --releaseworks as is.
The build embeds assets/. To use a different folder, set
SKIDS_ASSETS_DIR=/path/to/assets. To build without embedding, so the game
needs --data at run time, use --no-default-features --features audio.
The ADF images aren't needed to build.
GitHub Actions builds all three platforms on every push
(.github/workflows/build.yml).
Layout
assets/ the game data as editable PNG and text files
build.rs embeds assets/ into the executable
src/formats/ ADF (OFS/FFS), LHA (incl. -lh5-), CrunchMania, IFF 8SVX/ILBM, OctaMED
src/data/ track, vehicle and palette decoding; locating the game files
src/game/ physics, AI and race rules
src/render/ software renderer at 320×256 (PAL low-res) and a bitmap font
src/audio.rs sample mixer and sound effects (cpal)
src/music.rs OctaMED player
src/app.rs menus, race screens and results
Credits
Super Skidmarks is by Acid Software. This project is an unofficial revival for preservation. The CrunchMania bitstream layout follows Teemu Suutari's ancient (BSD-2-Clause).