JohnM
f5ab715755
The Predator script starts the missile 14000 units from its target, or 14000 above the player on maps without Predator spawn points. On Sub Base, Wasteland, Karachi, Invasion, Rundown, Carnival, Storm and Trailer Park that start is above the map's sky ceiling, a slab of sky brushes (contents 0x800; on Sub Base at z 8128-8192), and on Fuel a rooftop Predator starts inside it. The projectile trace uses MASK_SHOT, which includes the sky bit, so the missile hit the top of the slab about 1.75 s after launch and blew up some 7,900 units above Sub Base, with the view still a wash of fog. The Predator works on those maps in MW2, so it has to pass the ceiling there. A missile is now marked as remote-controlled when a player is linked to it as its pilot, and keeps the mark for its whole flight, since the control link is dropped when the pilot dies and the missile must still pass the ceiling then. The mark goes when the projectile is gone and on game shutdown. The marked missile's world trace leaves out sky brushes. A second, sky-only trace over the same tick still stops it on a sky wall or underside (a sky face with normal z of 0.7 or less) through the usual contact detonation, so a Predator steered sideways below the ceiling still ends at the edge of the map. A sky trace that starts inside a sky brush is ignored, which covers a missile inside the slab and the Fuel start. Every other projectile keeps the full mask: an RPG fired straight up still explodes on the ceiling. Checked on the Mac on Sub Base: the RPG still explodes at z 8127.9. The unsteered Predator passes z 8192 and reaches the ground about 5.4 s after launch, with a clear view of the base before impact (before: explosion at z 8192.1 after 1.75 s). A Predator whose pilot is killed about 1.5 s after launch still passes the ceiling and lands. One steered flat below the ceiling explodes on the south sky wall at y -15391.9. On our iPhone build in a Sub Base match, Predators reached the ground with a clear view before impact. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
IW4L
IW4L is an open-source runtime for Call of Duty: Modern Warfare 2 (2009), written in Rust with Bevy. Point it at a copy of MW2 you already own and it loads that installation's maps, models, textures and weapons into its own engine. You can try implemented movement and combat on multiplayer maps, then inspect or change how those systems work.
What you can try
Explore maps, fight bots, and record and replay demos. Gameplay remains incomplete; expect missing behavior, bugs and desyncs. The asset readers also cover MW3 and Black Ops.
APIs, configuration, caches and the wire protocol change between commits; multiplayer peers must run the same build.
Windows: prebuilt release
- Download
iw4l-windows.zipfrom Releases and extract it into an empty writable folder. The archive password ist.me/contextrot. - Launch
iw4l.exe. It finds MW2 in your Steam libraries and creates aModern Warfare 2.lnkshortcut next to itself. For an install outside Steam, create that shortcut to your MW2 folder yourself.
For online play, put the .iw4l-server file you received from a server operator next
to iw4l.exe. With it the game finds that master and updates itself on launch. Details:
Windows guide.
Build and run
Install Rust through rustup and GNU Make. Build dependencies cover Linux's C/C++ toolchain and system libraries, and macOS's Xcode command line tools. Windows instructions cover building and arranging a portable folder.
You need your own installed MW2 Multiplayer data. IW4L
distributes no game assets and reads installations without patching or replacing their
files. Caches, demos and logs go under iw4l-artifacts/; Linux settings use a separate
configuration directory described in the run guide.
From the repository root:
cp .env.example .env
# Edit .env: set IW4L_GAMES to the folder containing your game installations.
make map mp_boneyard CMDS='wait world; spawn 0; force_match_start; bot add 3'
This builds the optimized play profile and starts a local match with three bots.
force_match_start skips the warmup that otherwise freezes movement.
Inside the engine
| Area | Implementation |
|---|---|
| Assets | Native FastFile readers convert game data into a shared intermediate representation. |
| Shaders | Retail Direct3D 9 Shader Model 3 bytecode is translated to WGSL. |
| Rendering | World geometry, models and effects feed one sorted draw-surface list. |
| Simulation | Server authority, client prediction and replay share one simulation step over explicit Bevy ECS state. |
| Networking | Custom UDP traffic; a QUIC master provides browsing and relaying. The host simulates the match. |
Where to go next
- Run guide: console commands, classes and demo playback; master setup for playtests.
- Rendering and simulation: inspect the engine's implementation.
- Map loading, GSC runtime and bot AI: starting points for experiments and modifications.
- Documentation index, contributing and security reports.
This whole project is written by an LLM.
Acknowledgements and license
Thank you to all contributors for code, bug reports, testing and feedback. Special thanks to ju1cedr1nker and silvernote03 for QA testing weapons, maps, attachments and other gameplay features.
OpenAssetTools and its iw4x-x64 fork informed asset layouts; IW4x informed asset and protocol behavior; KisakCOD informed engine structure. Ghidra was used to inspect the original binaries.
Movement implementation history and source boundaries are recorded in its provenance note.
IW4L's source is licensed under Apache 2.0. Preserve required attribution and bundled font license texts when redistributing; see NOTICE. Original game assets and trademarks belong to their owners. IW4L is unaffiliated with them.