Gameplay Subsystem

Binary: MW4Mercs.exe | Classified VAs: 2525 | Exhaustive index: MW4Mercs.exe

Simulation state and rules: mechs, movers, pilots, missions, objectives, teams, sensors, vehicles, and the collision and geometry queries they use.

Role and boundary

Gameplay owns the simulation state that AI, combat, UI, and render consume. It is the largest subsystem by VA count, but most of it is object state and mission plumbing rather than a single algorithm. The recognizable islands are:

• the collision/geometry island at 0x00418000-0x0041DFFF;
• the mission, objective, team, pilot, and vehicle state in the general gameplay band;
• the game-state/save-load helpers grouped under state;
• the session/player table shared with the network layer;
• object and stream helpers that bridge gameplay data to the database and archive layers.

Gameplay is boundary-heavy. It calls render for presentation, AI for control, combat for fire and damage resolution, and archive/database for content and object storage. It should not be treated as a single self-contained module.

Player and mech object graph

The in-mission player graph is shared by gameplay, combat, and network code:

playerObj = [netinfo + slot*0x2038 + 0x3584]
mech      = [playerObj + 0x170]       // damage receiver
worldObj  = [playerObj + 0xD8]        // position/world entity
position  = [worldObj + 0x8C/+0x9C/+0xAC]

The player table is a fixed-stride array of 0x2038 bytes per slot. The per-slot flags at +0x3538, +0x353B, and +0x3544 control state sync, player-event broadcast eligibility, and the state-sent marker. A slot can be flagged active without a player object; the network layer relies on that.

The mech object is the damage receiver for the combat damage map. The world object is the position/velocity source used by missile guidance and camera code. The +0x170 and +0xD8 links are the stable gameplay-to-combat and gameplay-to-render handoffs.

Collision and geometry island

The 0x00418000-0x0041DFFF island contains collision math and the geometry queries used by movement, hit tests, and placement. It is mostly shared math, not mission rules:

VA	Role
0x00418880	transform a vector through the geometry helper
0x004188E0	sphere/OBB merge and bounds computation
0x00418A80	OBB-vs-OBB separating-axis collision test
0x00418F00	OBB-vs-OBB separating-axis test, second variant
0x004194E0	OBB/sphere cluster collision resolution
0x00419AD0	sphere-vs-sphere collision resolution
0x00419C00	sphere/point collision test
0x00419F90	Euler-angle to rotation-matrix conversion
0x0041A070	Euler-angle to rotation-matrix conversion, second form
0x0041A160	quaternion-to-rotation-matrix conversion
0x0041A2C0	3x3 matrix inverse (adjugate + determinant)
0x0041A460	4x4 matrix multiply
0x0041AA10	quaternion-to-Euler-angles conversion
0x0041ABB0	3-component vector interpolation
0x0041AFD0	4-vector normalization
0x0041B140	rotate a 4-vector by an angle
0x0041B320	Hamilton product of two 4-vectors
0x0041B3B0	4x4 matrix multiply (rotation + translation)
0x0041B680	fast 4-vector normalization
0x0041B720	fast quaternion normalization
0x0041BB80	quaternion slerp
0x0041BD00	quaternion lerp
0x0041C340	quaternion from a 3-vector
0x0041C540	squared-distance comparison
0x0041C610	quaternion from Euler angles
0x0041C680	3x3 matrix times vector
0x0041C6E0	transposed 3x3 matrix times vector
0x0041C7D0	3x4 matrix times vector
0x0041C830	quaternion/matrix multiply
0x0041C9B0	quaternion Hamilton product
0x0041CA30	4x4 matrix times quaternion
0x0041CAC0	3x4 matrix times 3-vector
0x0041CB30	transform a 3-vector by a 4x4 matrix
0x0041CFE0	4x4 matrix multiply
0x0041D3B0	3x4 matrix multiply with translation
0x0041D570	4x4 matrix construction from six floats
0x0041D780	angle normalization
0x0041D810	angle interpolation

The collision tests are separating-axis and sphere-based; the matrix and quaternion helpers are the shared transform layer used by gameplay, combat, and camera code. This island does not contain the mission rules or the mech damage model; those live in the gameplay state and combat paths.

Gameplay state

The general gameplay band owns the mission and object state consumed by the rest of the engine:

• mission and scenario state;
• objectives and completion flags;
• teams and affiliations;
• pilots and pilot-to-mech bindings;
• vehicles, movers, sensors, and other world objects;
• save/load and game-state flags;
• the database/session wrappers at 0x004D2B00-0x004D3200.

The state is object-oriented and vtable-driven. Many objects are created through the shared allocation wrappers and registered in the database; the gameplay code holds pointers and IDs rather than a single global state block. The network layer's player table is one view of that state; combat's damage map and render's scene nodes are others.

Object, stream, and serialization helpers

The upper end of the physics band and the following block contain shared object and stream infrastructure used by gameplay data:

• 0x0041D890 - object/collection constructor;
• 0x0041DAC0 - destructor/cleanup;
• 0x0041DC10 - stream/transform helper;
• 0x0041DE50 - stream object constructor;
• 0x0041DE80/0x0041DEC0 - writer open/close;
• 0x0041E690 - StreamReader initializer;
• 0x0041E720/0x0041E950 - StreamReader read/write;
• 0x0041EA60/0x0041EAE0 - bit read/write;
• 0x0041EB40/0x0041EC50 - multi-bit read/write;
• 0x0041F230/0x0041F270/0x0041F290 - int/string/float serializers;
• 0x0041F3D0/0x0041F430 - vector serializers;
• 0x0041F480/0x0041F500 - yaw/pitch/roll serializers;
• 0x0041F570 - unit-quaternion parser;
• 0x0041F680/0x0041F6E0 - motion parser/writer;
• 0x0041F750/0x0041F7B0 - RGB color parser/writer;
• 0x0041F800 - RGBA color parser;
• 0x0041F8D0/0x0041FA70 - tree/section save-load.

These helpers are shared by the database and archive layers. They are not gameplay rules, but they define how gameplay records are read and written.

Invariants and failure modes

• The player table stride is 0x2038; a slot's flags are independent of whether a player object is present.
• The mech is [playerObj+0x170]; the world object is [playerObj+0xD8]. Using one in place of the other produces wrong damage or guidance targets.
• Collision queries operate on transformed geometry; an uninitialized matrix or quaternion produces false hits or misses.
• The OBB tests use a separating-axis path; a degenerate axis (zero-length normal) is not a valid input.
• Sphere tests compare squared distances; the caller must not compare the result against a linear distance without squaring.
• The stream helpers are bit-oriented; a reader and writer must agree on the bit order and the flush state.
• The gameplay state is shared across subsystems; mutation must go through the owning object, not a cached pointer in another subsystem.
• The network player table and the gameplay object graph are views of the same state; they can diverge if one side is updated without the other.

Key entry points

VA	Detail	What it does
0x004188E0	physics	sphere/OBB bounds merge
0x00418A80	physics	OBB-vs-OBB collision test
0x00418F00	physics	OBB-vs-OBB collision test variant
0x004194E0	physics	OBB/sphere cluster resolution
0x00419AD0	physics	sphere-vs-sphere resolution
0x00419C00	physics	sphere/point test
0x0041A2C0	physics	3x3 matrix inverse
0x0041A460	physics	4x4 matrix multiply
0x0041BB80	physics	quaternion slerp
0x0041C540	physics	squared-distance comparison
0x0041CB30	physics	transform 3-vector by 4x4
0x0041CFE0	physics	4x4 matrix multiply
0x0041D570	physics	matrix construction from six floats
0x0041D890	objects	object/collection constructor
0x0041E690	stream	StreamReader initializer
0x0041E720	stream	StreamReader read
0x0041E950	stream	StreamReader write
0x0041EA60	stream	bit read
0x0041EAE0	stream	bit write
0x0041F230	stream	integer serializer
0x0041F290	stream	float serializer
0x0041F8D0	stream	tree/section save-load

Details

Detail	VAs	Responsibility
(general)	2396	Simulation and mission-state helpers not assigned to a narrower gameplay detail.
physics	91	Collision, OBB/sphere tests, and geometric queries.
state	38	Game-state flags, save/load, and session state.

Coverage

All 2525 classified VAs are in the MW4Mercs.exe index, which lists role, size, source, and evidence.