Carmageddon (dethrace-ported-to-web)
Carmageddon
About the project
Carmageddon es un videojuego de combate en vehículos creado en 1997 que destacó por incluir una proporción importante de violencia en su modo de juego. El juego tiene como misión principal acabar la carrera o destrozar los coches de los contrarios, no obstante la matanza de peatones es un aliciente. En su época sufrió duras críticas que irónicamente lo llevaron a los primeros puestos de ventas. El juego fue producido por Stainless Software y publicado por Interplay y Sales Curve Interactive (SCi).
3 versions of Carmageddon
You're viewing: Carmageddon (dethrace-ported-to-web)
Official project information
Carmageddon — Web Port
Play Carmageddon (1997) in your browser. This project compiles the open-source Dethrace engine to WebAssembly with WebGL 2 rendering and Web Audio sound.
Features
- Full single-player Carmageddon experience in a modern browser
- OpenGL renderer via Emscripten + BRender
- Menu, races, opponents, pedestrians, power-ups, replays
- Save games stored in the browser (IndexedDB via Emscripten IDBFS)
- Keyboard + mouse controls
- No install — static hosting only (HTML + WASM + preloaded data)
How it works
┌─────────────────────────────────────────────────────────────┐
│ Browser │
│ ┌──────────────┐ ┌─────────────┐ ┌──────────────────┐ │
│ │ index.html │──▶│ carmaweb.js │──▶│ carmaweb.wasm │ │
│ │ + pre.js │ │ (Emscripten │ │ (Dethrace engine │ │
│ └──────────────┘ │ glue) │ │ + BRender GL) │ │
│ └─────────────┘ └────────┬─────────┘ │
│ ┌──────────────┐ WebGL 2 canvas ◀───────────┘ │
│ │ carmaweb.data│ (game files preloaded to /carma) │
│ └──────────────┘ │
│ ┌──────────────┐ /persistent → IDBFS (save games) │
│ │ IndexedDB │ │
│ └──────────────┘ │
└─────────────────────────────────────────────────────────────┘
- Build — Dethrace 0.10.1 is cross-compiled with Emscripten to
carmaweb.wasm+carmaweb.js. - Game data — Retail
DATA/(and related files) are embedded at link time ascarmaweb.data(~190 MB) and mounted at/carmain the virtual filesystem. - Rendering — BRender’s OpenGL backend draws to an HTML5 canvas. Frame pacing uses Asyncify only during in-race presentation to avoid WebGL flicker; the menu swaps without extra yields.
- Audio — miniaudio drives Web Audio (ScriptProcessor). A user click/key press is required once to unlock
AudioContext(browser policy). - Saves — Only
/persistentuses IDBFS; game data is read-only from the preload pack.
Web-specific patches (summary)
| Area | Approach |
|---|---|
| Race rendering | Single emscripten_sleep per frame in SDL2_Harness_Swap only while racing |
| Menu / UI | No Asyncify between frames — stable menus, no flicker |
| Menu audio | SoundService() during interface loop; input waits yield with emscripten_sleep(0) |
| ESC → pause menu | WaitForNoKeys() yields so key-up events are processed |
| PIX duplicates (web) | Material colour-map refresh for duplicate pixelmaps |
Quick start (play locally)
You need a legal copy of Carmageddon on disk (not included here).
Requirements
- Emscripten SDK 3.1+
- CMake 3.20+, Ninja
- Python 3 (for local server)
- ~2 GB free disk space for build + data pack
1. Add game data
carmagit/
Carma/ ← your install root (name matters for default CMake path)
DATA/
MUSIC/
...
The build expects Carma/DATA/GENERAL.TXT to exist.
2. Build
Windows (PowerShell):
.\scripts\build-emscripten.ps1
Linux / macOS:
source ~/emsdk/emsdk_env.sh
chmod +x scripts/build-emscripten.sh
./scripts/build-emscripten.sh
This produces web/carmaweb.js, web/carmaweb.wasm, and web/carmaweb.data.
3. Run
python web/serve.py
Open http://localhost:8080 — hard-refresh with Ctrl+Shift+R after rebuilds.
Click the page or press a key once if audio is silent.
Deploying to static hosting
Upload the contents of web/ after a successful build:
| File | Purpose |
|---|---|
index.html | Page shell |
pre.js | WebGL + IDBFS + audio unlock hooks |
carmaweb.js | Emscripten loader |
carmaweb.wasm | Game engine |
carmaweb.data | Preloaded game assets |
Configure your host to serve large files (200 MB+) and correct MIME types (application/wasm for .wasm).
Note: Do not commit
carmaweb.dataor retail game files to a public GitHub repo unless you have explicit rights. Use Git LFS or host binaries separately (as on the live demo).
Controls (default keyboard)
| Action | Key |
|---|---|
| Accelerate | ↑ |
| Brake / reverse | ↓ |
| Steer | ← / → |
| Handbrake | Space |
| Camera | C |
| Repair | Backspace |
| Pause / menu (in race) | Esc |
| Horn | H |
Mouse works in menus. In-race camera look uses WASD (patched in pre.js / input layer).
Project layout
carmagit/
├── README.md ← you are here
├── NOTICE.md ← game asset copyright
├── .gitignore
├── docs/
│ └── screenshot.png
├── dethrace-0.10.1/ ← engine source (Dethrace + web patches)
├── web/
│ ├── index.html ← browser entry point
│ ├── pre.js ← Emscripten pre-load hooks
│ └── serve.py ← dev server (no cache)
├── scripts/
│ ├── build-emscripten.ps1
│ └── build-emscripten.sh
└── cmake/
└── Emscripten.cmake
Browser support
Tested on recent Chrome, Edge, and Firefox.
- WebGL 2 required
- WebAssembly required
- ~200 MB download on first load (game data pack)
- Recommended: desktop, hardware keyboard
Credits & license
| Component | License / source |
|---|---|
| Dethrace | GPL-3.0 — see dethrace-0.10.1/LICENSE |
| BRender, miniaudio, stb, etc. | See respective files under dethrace-0.10.1/lib/ |
| Carmageddon game data | Not included — commercial / rights-holder property |
This web port is a community technical project. It is not affiliated with or endorsed by Stainless Games or current rights holders.
Contributing
PRs welcome for web-specific fixes. Please do not submit copyrighted game assets.
When changing Emscripten link flags or the main loop timing, test both in-race driving (no jitter) and menu navigation (no flicker, no audio dropouts).