cod4.md

Call of Duty 4

vcod plays and hosts Call of Duty 4: Modern Warfare multiplayer, patch 1.7 only (the wire's protocol 6, told apart from CoD1 1.5's by the game). It needs a CoD4 install: zone/<language>/*.ff fastfiles beside main/ and its iwds. Put the binaries in it, or point --game-dir or COD_DIR at it (COD4_DIR is only for tests and tools). The game is detected from zone/ or iw3mp.exe; --game cod4 forces it. How to run each mode is in usage.md.

Research docs live in docs/research; the links below name the section that measured each claim.

What works

Client

Front end (cod4-front-end.md). Bare vcod opens 1.7's main menu, drawn and run from the ui_mp zone's menus with its mouse_over, mouse_click and music_mainmenu_mp sounds.

• Join Game: the pc_join_unranked browser. Local (a getinfo broadcast to 28960-28963), Internet (getservers 6 full empty to masterServerName, master.cod.pm by default) and Favorites (servercache.dat; vcod writes only the favourites). Pings, the filter popup, column sorts, Server Info's status, New and Del. Favorite, the password popup. The master is asked only on Refresh List (cod4-handshake.md 12).
• Start New Server starts vcod-server --game cod4; Dedicated No joins it. Server Name and Password are typed into it. In such a game the Graphics page greys as on 1.7's listen server.
• Mods runs a mods/<name> mod.
• Select Profile lists, creates, deletes and loads the profiles in players/profiles/. A fresh install asks for one first; the active profile holds the config.
• Options and Controls set what vcod has a cvar or bind for; the rest draw greyed.
• Esc on the connect screen, or disconnect, calls the join off. Leaving a game or a server's drop returns to the menu with the reason in error_popmenu (7).
• Aspect Ratio (r_aspectRatio, at vid_restart) projects at 4:3, 16:10 or 16:9 over the whole window, as 1.7 does; fullscreen stretches the HUD with it (10).

Mods, usermaps, downloads (cod4-fastfile.md 13, cod4-handshake.md 11):

• --fs-game mods/<name> or a joined server's fs_game loads the mod's mod.ff and iwds over the stock zones and main/ in 1.7's order. The HUD and script menus read mod.ff too (ModWarfare's class menus). Prediction uses the mod's weapon files off its iwds, as the server does.
• A map missing from zone/<language>/ loads from usermaps/<map>/. <map>_load.ff gives the connect screen its levelshot.
• Missing mod or usermap iwds and fastfiles download before the map loads (cl_allowDownload, on by default), over UDP or a www redirect's http:// under cl_wwwDownload; a failed fetch falls back to UDP. A file still different on the next gamestate ends the join, as on 1.7.

Joining and the script menus (cod4-hud.md 12):

• --connect or the browser joins a stock 1.7 server (retail or vcod-server), stats phase and pure cp included, as a player or a spectator.
• The server's script menus draw from the zones as 1.7 draws them: the team menu, changeclass, changeclass_offline, with rects, materials, text and visibility expressions over the dvars, the profile's stats and the string tables. Every expression of the 288 menus the HUD's zones and mp_crash carry evaluates (12.2). Mouse, arrows and Tab move focus; click or Enter picks; Esc runs onEsc.
• With no menu up, Esc opens g_scriptMainMenu: the team menu, then the in-game class menu (Choose Class, Change Team, Controls, Options, Call Vote, Mute Players, Leave Game).
• Controls rebinds a row on a click and the next key, saved to vcod_mp.cfg. Options sets sensitivity, invert, free look, smoothing, r_gamma, sm_enable, cg_marks, volume, downloads, name, video mode, refresh, anti-aliasing, sync, aspect, glow, specular, dynamic lights, model detail, water animation, texture filtering and quality, anisotropy, blood, console, depth of field, soft smoke edges and ragdoll (12.6).
• Call Vote sends retail's callvote (restart, next map, a map, a game type and map, a temp ban). Mute Players mutes a player's chat and voice.
• --team and --class (e.g. assault_mp,0) answer the menus on their own.

Input. A cmd a frame off the binds: move, sprint, jump, stances, attack, the sight (+speed, toggleads, +toggleads_throw), melee (V), use, reload, lean, hold breath (+breath_sprint), frag and smoke, weapnext / weapprev. +actionslot switches to the grenade launcher, the slot's weapon or the night vision goggles. T and Y open the say field. The weapon byte is the client's own pick (cod4-client-view.md 9, cod4-hud.md 12.6).

Netcode and prediction (cod4-client-view.md):

• The snapshot view on retail's client clock (CL_AdjustTimeDelta) and lerp, with its teleport cuts.
• Our own body and a free spectator are predicted: cmds replayed through vcod_cod4::pmove over the map's clip map and the other players' boxes. Corrections ease over cg_errordecay's 100 ms, stair steps over cg_viewZSmoothingTime. Mantles and the weapon half predict too, so our own shots, reloads, switches and footsteps play the frame the predicted move raises them, and not again from the snapshot. Item pickups stay the snapshot's (5).
• A lean moves the eye sideways as 1.7's does (7).

Bodies and entities (cod4-player-anims.md):

• Players and corpses posed from legsAnim / torsoAnim with heads and held weapons. Aim pitch, lean and prone pitches bend the spine and head as 1.7's controllers do.
• Corpses go ragdoll on the server's startRagdoll: ragdoll.cfg's bodies under a position-based solver. Grenade, rocket and script blasts push them; bullets do not, as on 1.7 (10).
• Dropped weapons, grenades and movers on their trajectories. Script models without their hidePart parts, so a damaged car draws intact or cracked glass, never both (cod4-client-view.md 15).
• The airstrike's jets and the helicopter with turning rotors, rotor wash, damage-stage smoke and fire, and playFxOnTag effects on any model's tags (11).
• Mounted guns with barrels at the wire's gun angles and their fire anim. A gunner's eye sits at tag_player; other gunners sit on their guns.

View weapon and view (cod4-client-view.md 4, 14):

• The held weapon's view model at cg_fov 65 with the sight's zoom. Its clips follow weapAnim (idle, fire, reload, raise, drop, sprint, melee with the knife) under the sight layer. hideTags hides missing attachments. A reflex sight's dot projects off the view angle.
• Move offsets, idle drift, bob and sway; own flash and shell eject on tag_flash and tag_brass; recoil spring, damage kick, landing dip.
• Shot recoil kicks the view through the cmd's angles; a hit kicks it along its direction.
• Shellshock from the zones' .shock records: a flashbang's or concussion's white-out over a still of its first frame, the camera kick, the concussion's mouse caps, the flashbang's tinnitus and sound mix (8). Earthquakes shake the view.

Rendering (cod4-world.md):

• World and static models out of the map's zone: textures, lightmaps, the sun, the sky cube, blends and alpha tests, doorway lighteners and light shafts' angle falloff, culled by cells and portals. A census holds every world and static model material of the 21 stock maps to its retail state bits.
• Normal, specular and detail maps under the sun. Static models lit off the light grid as the lp_* techniques read it; specular sets add their reflection probe. A surface on a spot or omni primary light takes it in the sun's place.
• Sun shadows (sm_enable, default 1): world, static models and entities in retail's two-partition sun shadow map (3.6).
• Spot light shadows: up to four in view (sm_maxLights), fading in and out (r_spotLightShadows, sm_spotEnable; 3.5).
• Exp fog (setExpFog) and the vision set's film tweak and glow: mpintro's grey easing to the map's over 2 s, and the night set under night vision. r_glow 0 and r_fog 0 are cheats, as on 1.7 (11).
• Water as 1.7's water_l_sun over a moving height map. The world's distortion glass (mp_overgrown's bricks) and zfeather sets (floodlight beams, lens flares) (9).
• Depth of field down the sight (r_dof_enable), heat haze from explosions, fires and muzzle flashes (r_distortion), and zfeather sprite fades (r_zFeather) (cod4-effects.md 14, 17).
• vc_windowAspect 1 (vcod's) projects at the window's own aspect instead (see Beyond retail).

HUD (cod4-hud.md):

• Hudelems in the zones' fonts with glow. Kill feed with weapon icons, iPrintLn and iPrintLnBold, chat, the obituary's centre print, [{+cmd}] key names.
• Rotating minimap compass: teammates (kept 1.5 s after they drop out), pingPlayer flashes, talkers, radar enemies, the UAV sweep, shot flashes held for the fire sound, objectives, the tickertape, the helicopter and airstrike planes (15).
• Weapon HUD: the clip as bullets, weapon name, offhand icons and counts, a low clip's red pulse, a low reserve in red. The action slots (night vision, grenade launcher, earned hardpoints).
• Low-health overlay and hit direction icons (19), cursor hints with key names (20), grenade indicators (21), mantle, hold breath and invalid command hints, XP and score bars (23).
• The crosshair with the weapon's spread (Steady Aim's narrower), scope overlays, a mounted gun's reticle, cg_crosshairDynamic (17).
• World waypoints (Bomb Squad's icon over enemy claymores and C4) and offscreen ones with a pointer.
• The killcam's letterbox and title; the prematch's countdown text. The compass and ammo counter hide under ui_hud_hardcore.
• The scoreboard on Tab and at intermission: header, team scores, game type, time left, talking icons, scrolling, cg_scoreboardPingGraph (7).
• The full map while picking an airstrike's location.
• The connect screen: levelshot, glowing titles, stage line, load bar, download rate and time left, a server's print and the CD key wait (18).
• The drop-down console in consoleFont; say, cmd and unknown commands go to the server.

Sound (cod4-sound.md). Zone and iwd sounds through each alias's falloff curve and, on 2D rows, its speaker map's stereo level: footsteps (Dead Silence's quiet ones), landings, shots at the shooter's tag_flash, reloads, hits, bounces, explodes, the knife, the map's ambient, entity loop sounds (a brush model's at its middle), playSound and playSoundAsMaster. EV_STOPSOUNDS stops an entity's voices. A voice started off its entity turns round it.

Effects (cod4-effects.md), on the CoD2 effect path:

• Muzzle flashes and shell ejects on the posed weapon's tags, impacts, explosions, effects emitted along an element's flight, missile smoke trails on tag_fx.
• Looping effects for their whole life: spawnFx, playLoopedFx and the map's createfx ambience (mp_crash's fires start settled). Each element spawns inside its spawnRange and fades over its distances.
• Client-side bullets: every round traced from the eye (ours) or the muzzle (others') with the server's seeded spread, stopping on players' boxes and script models, piercing the world with exit impacts (Deep Impact deepens it), with impact sounds, holes, whizby and 1.7's corkscrew tracers (12).

Voice chat (cod4-voice.md). +talk (Z) sends the microphone through the system's libspeex (narrowband, 8000 Hz, sv_voiceQuality); talkers play, and the talker list and scoreboard show who talks. Without libspeex nothing is sent or played.

Demos (cod4-demos.md). record writes 1.7's typed records into main/demos/ (the mod's under fs_game). demo <name> and timedemo <name> load the map behind the connect screen and play it unpredicted, the recorder's view off its archive rows.

Server

vcod-server <map> --game cod4 runs cod4::Cod4Server over game::cod4::level::Cod4Level. The level defaults to war (--gametype or --set g_gametype= picks another).

Handshake (cod4-handshake.md):

• getinfo, getstatus, the challenge, the connect and the seven stats packets as retail answers them; the gamestate with retail's engine configstrings and the script's; the pure cp check (9).
• Off the LAN it refuses on sv_minPing / sv_maxPing and holds a client out of the world to a message a second, as 1.7 does (15).
• sv_fps (10..1000, default 20) sets the frame, read every frame; the scripts' wait counts frames as on retail (cod4-server-frame.md 8).
• Mods (--set fs_game=mods/<name>) and their downloads over UDP (sv_allowDownload) or sv_wwwBaseURL (11). --script-dir reads loose .gsc files over the zones'.
• --set dedicated=2 heartbeats master.cod.pm (or the master sv_master1 names) every 180 s.

Scripts (cod4-gsc.md). The stock gsc runs on vcod's VM. Every builtin the stock scripts of the 21 stock maps call has a handler (3.1).

• The connect, team and class menus (mr), the loadout off the client's stats block, the spawn, with retail's server commands in retail's order. A client on a team with no class follows a teammate (7).
• setStat sends 1.7's N to the client's profile.
• The script's HUD elements go out in the playerstate, matched element for element against retail captures (cod4-hud.md 5.1).
• Every perk acts: the scripts' damage, loadout and Last Stand ones, and the engine's (spread, reload, fire rate, breath, sprint, Deep Impact, Martyrdom's dropped grenade, Last Stand's down state, Eavesdrop) ("The perks").
• Looping and triggered map effects go out as ET_LOOP_FX and ET_FX.
• Hardpoints: the airstrike's three ET_PLANE jets and their bombs; the helicopter (ET_HELICOPTER) flies its path, aims and fires its cannon and rockets, pitches and rolls off its acceleration, wanders in the hover, and smokes and crashes when shot down (3.2).
• bulletTrace scores bodies' posed hit boxes and the helicopter; getTagOrigin reads a player's posed bone (3.3).
• The use key and touch pass reach game object triggers, trigger_use and dropped weapons (swap the gun in hand). A planter raises the briefcase (9).
• The six stock mounted SAWs (misc_turret, ET_MG42) show their hint, mount on use, hold the view in their arcs, fire off the turret's weapon file and let go on a second press, matching the retail mp_backlot capture (9.2). A live frag lying near a player shows its hint, and the frag key throws it back on its own fuse (9.3).

Movement (cod4-pmove.md). Each cmd runs 1.7's pmove as it arrives, over the clip map and the other bodies. A walker replaying a retail capture moves as on retail within the trace kernels' float model (0.04 units over 40 s) (15). Mantles over MANTLE_ON and MANTLE_OVER walls on 1.7's clips and timing, leaving 1.7's blockage for other players (17). Bodies carry the legs and torso anims 1.7's anim script picks, with view angles, lean and prone pitches. Spectators follow as scr_game_spectatetype allows: attack to the next player, the sight to the one before, melee to fly free (15).

Combat (cod4-combat.md), matched against a retail kill capture, entity numbers included:

• Bullet weapons fire, burst, reload and sight as PM_Weapon runs them.
• A round leaves the eye with walk bob and lean along the gun's angles (sway, movement tilt, idle drift, recoil spring), through retail's line on every round of a strafing, leaning capture (3.2).
• Rounds trace posed hit boxes through the antilag and penetrate walls and bodies by 1.7's depth table (a round through a mp_crash wall takes retail's damage). They meet script models' collision triangles and brush models, and go on past them (13.1).
• Destructible cars and barrels break under rounds and blasts (13).
• The stock damage and killed callbacks, the obituary, the corpse (death anim, set down on the ground, startRagdoll at retail's moment), the dropped weapon (its ammo handed to a player holding the same gun), and the killcam with the world as it was.
• Frag, smoke and flash grenades are pulled, cooked, thrown and bounce, off static models too. A replayed frag matches retail word for word, spin included: the server draws glibc rand() as 1.7's one stream (10.9). Blasts do radius damage; flashbangs blind and concussions shock and slow (10.8). The grenade launcher and the rocket launcher fire.
• Rockets wobble, curve and accelerate as 1.7's do; an RPG bends toward the helicopter's attractor; the helicopter's guided rockets steer.
• Melee swings and hurts; kill works under sv_cheats (10.4, 10.5).
• A rocket's flight has no retail capture to gate on yet (12).

Voice (cod4-voice.md 3). Relayed under sv_voice 1 (off by default, as retail): team, dead to dead, voice_global, voice_deadChat, voice_localEcho, Eavesdrop's 400 units, mute lists, isTalking().

Map cycle (cod4-map-cycle.md). map, devmap, map_restart, fast_restart and map_rotate over sv_mapRotation (server_map.cfg fills it with the stock maps). A match that ends rotates or restarts through the intermission's scoreboard, ranked (sv_pure 1) included. callvote and vote run 1.7's engine vote. A client that leaves or reconnects into its own slot leaves no stale player in the scripts.

Admin and logs (cod4-handshake.md 14, cod4-server-gaps.md):

• score gets retail's b board (cod4-hud.md 7).
• rcon: status, serverinfo, systeminfo, dumpuser, say, tell, clientkick, kick (bans for sv_kickBanTime; kick all), onlykick, tempBanClient, tempBanUser, banUser, banClient, unbanUser (ban.txt, --ban-file), heartbeat, killserver, the dvar commands (set, seta, setu, toggle, togglep, reset, setfromdvar, dvar_bool/int/float, setdvartotime), writeconfig, vstr, exec (a zone's rawfile, then iwds and files in 1.7's order), cmdlist, and the map commands.
• g_log writes 1.7's games_mp.log: InitGame, ShutdownGame, ExitLevel, chat and weapon lines and the scripts' J;, Q;, D;, K;. g_inactivity warns and drops idle players.

Bots

--bots N [--bots-shoot] adds bots that join through the team and class menus and play with vcod's shared bot brain (bots.md):

• Find their way over a graph of the map's clip map, mantles included.
• Play the sd and sab bomb (take, carry, plant, defuse), dom's flags and koth's radio, and rejoin each new level.
• Man a SAW covering a lane enemies use; throw a live frag at their feet back.
• See an enemy only past every car that would stop the round.
• addbot, removebot (kickbot), listbots and the vc_bot_* cvars work as on CoD1.

Tools and test gates

Most need COD4_DIR and pass vacuously without it.

Tool	What it checks
moves_ab (crates/cod4/tests)	pmove against retail move captures (cod4-pmove.md)
cod4_combat_ab, shot_aim_ab	shots, damage and kills against a retail capture (cod4-combat.md)
cod4::wire_ab	the server's walk replay and follow against retail
hardpoint_ab, planefx_ab, prematch_ab, oob_ab	hardpoints, plane effects, the prematch HUD, connectionless replies
census tests (crates/cod4/tests)	every stock map's materials, clip, cull, sun shadow, sounds, effects, HUD assets
cod4_live_*	a vcod-server and client in process on a simulated clock
cod4_map_sweep (ignored)	every stock map under war, dm, sd, sab, dom and koth with bots and a playing client (cod4-map-sweep.md)
tools/cod4_soak.sh	the client playing a whole match per map through main's frame
tools/cod4_perf.sh	client frame time, SWEEP=1 per setting (cod4-client-perf.md)
GAME=cod4 bot_match, nav_build	seeded bot matches and the bots' graph (bots.md)

Missing compared to retail

Ranked by how much a player notices. The research-side lists are cod4-gaps.md (client) and cod4-server-gaps.md (server).

1. CoD4x servers. Most public CoD4 servers run CoD4x, which parks a 1.7 client and hands it to CoD4x's own update backend. vcod refuses them at the challenge and hides them in the browser unless ui_browserShowCoD4x is 1 (cod4-handshake.md 13). vcod joins stock 1.7 servers only, which are rarer than they should be.
2. Ranks and unlocks start fresh. vcod keeps its own stats file per profile (vcod_mpdata) and never reads retail's mpdata. The main menu reads a fresh profile's stats, so Create a Class is greyed and Rank & Challenges shows nothing earned (cod4-front-end.md 4). Your retail rank is safe, and no use here.
3. Physics debris stays put. A physicsLaunched part (a car's door or hood) keeps the spot it stood on: the client runs no rigid-body physics for TR_PHYSICS. Ragdolls use vcod's position-based solver, not ODE, so corpses fall differently (cod4-gsc.md 3.2, cod4-player-anims.md 10).
4. View weapon details. No camo; every gun draws its first model. The rocket on a launcher and the goggles model are not drawn, and Sleight of Hand does not speed the view clips.
5. Mantle anims on others. The server's anim script skips the mantle movetypes, so another player climbing a wall plays no mantle anim (cod4-pmove.md 17.5).
6. Stereo only. A 5.1 or 7.1 device gets the stereo mix on its front pair (cod4-sound.md 5). 139 alias rows whose curve no zone holds fall off straight.
7. No third-person view, so our own third-person tracer start is not modelled (cod4-effects.md 12.3).
8. Demos untested against retail. No retail demo has played in vcod, nor vcod's in iw3mp.exe. The RECORDING line draws at CoD2's place (cod4-demos.md 7).
9. Small menus. The CD key menus are missing; Single Player's Yes does nothing (this is a multiplayer client); the winvoice_* voice settings are not read.
10. Server-side differences. vcod-server never asks the authorize server, so it answers an off-LAN challenge at once where 1.7 waits on the authorize server (cod4-handshake.md 15). The helicopter's flight has no move trace or touch and its collision traces at the bind pose (cod4-gsc.md 3.2). No PunkBuster (a stock dedicated server runs none either).

Pending human checks: pixel and by-ear comparisons with retail.

Beyond retail

• Bots on war, dm, sd, sab, dom and koth.
• vc_windowAspect 1 projects at the window's own aspect, Hor+ off the 4:3 view, with the HUD unstretched: compass, score and weapon info at the window's edges, centred pieces in the middle (cod4-front-end.md 10).
• Esc on the connect screen calls the join off. 1.7's Esc does nothing there, which never made sense.
• The browser's Internet list comes from master.cod.pm.
• r_vc_depthprepass (default 1): a depth-only pass first, which also writes the feathered effects' floatZ, so the frame needs no depth copy (cod4-client-perf.md 12, 35). r_vc_normalMaps and r_vc_film are debug switches for the perf sweep.
• VCOD_FRAME_PROFILE and tools/cod4_perf.sh measure the frame.

Debug and developer modes

• vcod <map> --game cod4 flies a stock map offline: the world, the map's createfx effects (settled as on a level a minute old), its ambientPlay loop, fog and vision set. It runs no game.
• vcod --game cod4 --capture <file> replays a cod4_probe datagram capture; the fly keys move the camera.
• vcod --net-probe ip:port --game cod4 [--team T] [--class C] joins headless and prints the menus the server opens and the spawn.