A map viewer, spectator client and (skeleton) dedicated server for Call of Duty (2003), patch 1.1, written in Rust. It reads the game's own pk3 archives, renders maps with their lightmaps and props, lets you walk them with the original movement rules, and speaks the real 1.1 network protocol well enough to spectate a live multiplayer server with players, animations, HUD, sound and combat effects.
- Loads any stock or custom map from an installed copy of the game and renders it textured, lightmapped, props included. Fly around freely.
--walkspawns you as a soldier with Quake 3 derived movement: gravity, stances, stepping, wall sliding, leaning, and the kar98k viewmodel playing the game's own xanim clips.--connect <ip:port>joins a CoD 1.1 server as a spectator. The client does the handshake, Huffman coding, netchan, delta snapshots and usercmds, follows the server's spectator camera, and renders every player as an assembled soldier playing the server-driven animations. Kill feed, chat, scoreboard, sounds, tracers, impacts and muzzle flashes come from the same events the retail client reads. It downloads maps it does not have, the way the retail client does.vcod-serveranswers server browsers, accepts connections and hands out the gamestate, so a retail 1.1 client loads the map. It sends no snapshots yet.
The whole thing runs on wgpu and winit, so in principle it is cross-platform. I have only run it on Linux.
It is a Cargo workspace of three crates. crates/common holds the file
formats, collision, movement and the 1.1 protocol, shared by the client and
the server; nothing in it imports wgpu, winit or kira. crates/client is the
window, renderer, HUD, effects and audio; crates/server is the dedicated
server. AGENTS.md is the contributor guide.
Mostly to see whether it could be done. Call of Duty 1 is an id Tech 3 descendant, and the Quake III Arena and Return to Castle Wolfenstein sources are public, but the 1.1 wire protocol has never been written down. Every field width, every enum order, every place where Infinity Ward diverged from RTCW had to be recovered from the binaries and confirmed against the retail server. That recovered protocol is documented in docs/protocol-1.1.md and is probably the most useful thing in here.
The other reason is that it is fun to watch a 2003 game come back to life in a window you built yourself.
Most of the code and documentation in this repository was written by an AI coding agent working under my direction. I decide what to build, review what comes back, run it against the real game and the retail server, and do the pixel-level and by-ear checks the agent cannot. The research docs record for each fact whether it was verified live or only inferred from a decompilation, so you can tell the two apart. Treat the code as a working prototype, not a reference implementation.
- A purchased, original copy of Call of Duty (2003) installed with patch 1.1.
This repository contains no game data. The 1.5 patch ships the same
pak0-4.pk3assets, so a 1.5 install also works as the asset source; the netcode and the reverse-engineering notes are about 1.1. - Rust 1.90 or newer; the dependency graph requires it.
- For the client, a GPU and driver with BC (DXT) texture compression. wgpu
picks whatever backend it finds (Vulkan, DX12, Metal, GL);
WGPU_BACKEND=vulkan|gl|dx12|metalnarrows the choice. The server needs no GPU. - I have only tested on Linux. Windows and macOS are unverified.
- Optional, for sound: a working default output device. Without one the client logs a warning and runs silent.
cargo build --release
builds target/release/vcod (client) and target/release/vcod-server.
cargo build -p vcod or -p vcod-server builds one of them.
The binaries expect to sit inside the game install, next to CoDMP.exe, and
read the paks from its main/ subdirectory. Either copy them there, set
COD_DIR=/path/to/CallOfDuty, or pass --game-dir. --game-dir beats
COD_DIR, which beats the executable's own directory, with the working
directory as the last resort.
COD_DIR=/path/to/CallOfDuty cargo test
Without COD_DIR the tests that need game data return early and report ok,
so a green run on a machine without the game proves nothing about the
parsers. The net-protocol tests read committed captures and run anywhere.
vcod mp_pavlov
vcod mp_pavlov --walk
vcod --list
vcod --connect <ip:port>
vcod mp_pavlov --game-dir /path/to/CallOfDuty
- The first positional argument is the map name (case-insensitive).
--listprints every.bspin the search path instead of opening a window.--mod-dirselects which subdirectory's pk3s to index:mainfor retail CoD1 (default).uofor United Offensive is accepted but untested; nothing proves its maps load.--walkstarts at a player spawn point as a collidable soldier. Needs a map with a spawn entity and collidable geometry.--connect ip:portspectates a live server. To find a populated one, the master server atcodmaster.activision.com:20510still answersgetservers 1 full empty.--debug-overlay(or F3 at runtime) shows frame time, draw stats, net and audio counters.--no-audioruns silent;--volume <0..1>sets the master volume.--net-probe ip:portis a headless client that prints what it receives and dumps captures totmp/under the current directory. It is the netcode debugging tool; details in AGENTS.md.
vcod-server mp_carentan --port 28960 --hostname "my server"
vcod --connect 127.0.0.1:28960
The server binds 0.0.0.0 and, like the retail server, answers getstatus
from anyone and honours an out-of-band disconnect by source address. Run it
on a LAN or behind a firewall you control. --max-clients sets
sv_maxclients (default 8). --game-dir, --mod-dir and COD_DIR work the
same way as for the client.
Click to capture the mouse, Esc to release it, mouse to look around.
| Input | Action |
|---|---|
| W / A / S / D | Move forward / left / back / right |
| Space | Move up |
| Ctrl | Move down |
| Shift | Speed boost |
| Scroll | Adjust fly speed |
In spectate mode the position comes from the server; the mouse drives the look angles. Hold Tab for the scoreboard. A map change on the server shows a loading screen (and downloads a missing pak the way the connect does) and continues on the new map.
These work in every mode:
| Input | Action |
|---|---|
| F3 | Toggle the debug overlay |
| F4 | Culling: on, locked (freeze the visible set), off |
| Input | Action |
|---|---|
| W / A / S / D | Move forward / left / back / right |
| Space | Jump (re-press to jump again, no autohop) |
| Ctrl | Crouch (held) |
| Z | Toggle prone |
| Q / E | Lean left / right |
| Shift | Slow walk |
| LMB | Fire (hitscan, leaves an impact mark) |
| RMB | Aim down sights (held) |
| R | Reload |
- Shadow-decal prop models (
shadow_tree_*,shadow_crateand similar) should draw as coplanar decals; they go through the opaque prop pipeline and show up as hard-edged dark patches. - Props are lit by the compiler's per-entity
lightingPrecalctint, one colour for the whole model. The engine samples its light grid per vertex. - No shader effects: Q3-style shader script semantics (blending, animation, scrolling) aren't implemented.
- Visibility follows the retail cells and portals but without the portal bevel planes and the brushmodel occluder volumes, so a little more is drawn through doorways than retail draws. Outside every cell (fly mode above the map) only the frustum culls, and a cell whose top is below the camera is frustum-culled directly: retail assumes nobody looks over a cell's walls.
- Alpha surfaces (foliage, fences) are alpha-tested only, and they collide as drawn, so a bush or a wire fence stops the player like a solid wall.
- Submodels (doors, exploding walls, moving platforms) collide by their render triangles, not their brush hulls.
- Bullet impacts in walk mode are one generic mark plus a smoke puff. Marks share the 256-entry decal ring with spectate effects; the oldest go first. Spectate mode picks the per-surface effect the way the retail client does.
- No swimming, ladders or mantling. Water collides like solid ground.
- No occlusion and no doppler: a sound through a wall is as loud as one in the open. The engine's same-entity channel replacement is implemented, but there is no priority-based voice stealing; when kira's mixer is full new sounds are dropped.
- Quick chat (
vsay) is not handled. The server commands that carry it (j/k/l) are documented in docs/protocol-1.1.md only. - Audio fidelity is matched to the retail engine on paper (falloff, panning, channel replacement, ducking) but not yet confirmed by ear against the real game.
- The server sends no snapshots, so a connected client waits at the loaded map until it times out.
- docs/protocol-1.1.md: the CoD 1.1 wire protocol, both directions, with the list of every divergence from RTCW/Q3 at the end.
- docs/research/: per-subsystem notes recovered from the binaries and confirmed live: the BSP, xmodel and xanim formats, the clientState stream, the player model and animation system, the event and effect tables, the efx grammar, the HUD protocol, the sound system, and the retail server's handshake. Each claim cites the module and address it rests on and says whether it was verified live or inferred.
- tools/re/: the small scripts used to pull tables out of the binaries (event enum, netfield tables, xrefs, a Ghidra export script) and the disassembly notes for the Linux server.
- AGENTS.md: working notes for contributors and coding agents: layout, test setup, netcode debugging, the reverse-engineering workflow.
- Quake III Arena and Return to Castle Wolfenstein by id Software, GPL. CoD1 is an RTCW-MP descendant and its netcode, movement and animation code follow those sources closely. Where vcod ports a routine, the comment names the file it came from.
- ioquake3, for a cleaner reading of the same netcode.
- CoDExtended, a GPL server extension for CoD1 1.1 whose reverse-engineered struct layouts were the starting point for the netfield tables.
- cod-asset-importer, a GPL Blender add-on for CoD assets; the xmodel triangle-strip decoder is ported from it and the xmodel layout was cross-checked against it.
- wgpu, winit and kira for graphics, windowing and audio.
vcod is not affiliated with or endorsed by Activision or Infinity Ward. Call of Duty is a trademark of Activision Publishing, Inc. This repository contains no game assets, no game code and no binaries from the game; it reads the files of a copy you own. The reverse engineering was done to interoperate with the game's own files and servers. The research notes document file formats and the network protocol for that purpose: they contain layouts and addresses recovered from the binaries, and no copied code. The screenshots above show art owned by Activision.
Quake III Arena and Return to Castle Wolfenstein are trademarks of id Software. Their GPL sources, and the other ported code, are credited in NOTICE.
GPL-3.0-or-later; see LICENSE. The network code was written with the RTCW (GPLv3) and Quake 3 (GPLv2-or-later) sources as reference, so the project is GPL to stay compatible with them.