Config Subsystem¶

Binary: MW4Mercs.exe | Classified VAs: 13 | Exhaustive index: MW4Mercs.exe

options.ini/config-file framework, option registry, and persistence.

Role and boundary¶

The config subsystem owns the game's text configuration file, options.ini, and the generic INI tree behind it. It has two layers:

the options layer at 0x00406ED7-0x00407BD8, which loads/saves the game's settings and binds named keys to option globals;
the generic INI framework at 0x0040DCA0-0x0040E4A0, which parses a file into a section/key tree, looks up or creates entries, and serializes the tree back to disk.

The file lives in the game directory. The game rewrites it from the in-memory tree when an option changes, so a value edited by hand is only persistent until the next automatic save.

File format¶

options.ini is a conventional sectioned text file:

[graphics options]
lod=-1000000
...
[sound options]
...
[special commands]
...
[server]
allowed=...

The observed game-written file has seven sections: graphics options, sound options, special commands, server, joystick, MSR spectator, and network options. Values are typed by the option registry:

Type	Encoding
bool	`true` / `false`
int	decimal
float	`%.6f`
hex	lowercase hexadecimal, no `0x` prefix
text	raw string

The parser reads the last duplicate of a key; the serializer emits every section in tree order. Line endings are CRLF. Comments and blank lines are not semantic to the loader, though the file writer preserves a stable layout.

Generic INI tree¶

FUN_0040DCA0 is the config-file load constructor. Its arguments are the filename, a mode, and a flag; it stores the path at [this+0] and the mode at [this+8]. The loader calls FUN_006FC4D0 to read the file and FUN_0041DEE0 to build the tree through FUN_00412BF0. Mode 1 is the "required" mode: an empty tree asserts with "%s is missing or empty!".

The tree operations are:

VA	Operation
`0x0040ECC0`	look up a named entry/section
`0x0040EDA0`	look up or create a section
`0x00411A10`	find a key node
`0x00411B00`	create a key node
`0x00411C40`	set a key's string value (`__thiscall`, `RET 8`)
`0x00411D60`	bind a tree key to a global variable
`0x00411DC0`	set a value (used by the LOD teardown write-back)

FUN_0040E4A0 saves the tree. It checks the dirty flag at [this+4] and the path at [this+0], opens a writer with FUN_0041DE80, serializes every section through FUN_0040E450 and FUN_00411940, closes with FUN_0041DEC0, and clears the dirty flag.

Option binding and the LOD path¶

The options layer registers and binds named keys. FUN_00411D60 is the live binding path: it associates a section/key with a global so that a loaded value propagates into game state. The LOD teardown FUN_004BC4A0 writes the global back through FUN_00411DC0.

The LOD registration at FUN_004BC290 also calls FUN_0070F090 to expose four gosScript variables. FUN_0070F090 is a RET 0x14 no-op, so those four getter/setter pairs are dead code: the gosScript variables are never created, and the game has no in-session LOD control. The live value comes from options.ini or autoconfig_MERCS.exe.

LOD bias model¶

The renderer's LOD bias is applied as:

d2_biased = dx*dx + dy*dy + dz*dz + lod

A LOD band matches while lo <= d2_biased <= hi. A positive bias makes the object switch to a coarser LOD sooner; a negative bias keeps it finer for longer. A very negative value such as lod=-1000000 clamps everything nearer than sqrt(|bias|) to d2 = 0, selecting the finest band. It does not extend the object cull radius.

The game's in-session LOD checkboxes write 0, 625, 2500, and 10000. autoconfig_MERCS.exe writes Low 2500, Medium 900, High 400, and Ultra High -25000 through its switch table at 0x00402110.

The bias feeds the scan/fade and sub-object variant paths, including 0x004B40B0/0x004B4230, 0x004B5950/0x004B5B80, and 0x004B0BB0/0x004B1590/0x004B252B/0x004B49CB.

options.ini call sites¶

The string "options.ini" appears at 0x0076C6B4 and 0x0077826C. Load/save calls are spread across the options function FUN_00406ED7 (the large 0x00406ED7-0x00407BD8 block) and the network, render, input, and session paths. Representative call sites include 0x00401E03/0x00401E27, 0x00402DAB/0x00402E44, 0x00403046/0x004037FE, 0x004046E0/ 0x0040478C, 0x004066A1/0x0040671D, 0x00406F7F/0x00406FC7, 0x00407586, 0x0040793D/0x004079CE, 0x00407A08/0x00407B09, 0x0050A639/0x0050A695, 0x0050B5CF, 0x0050C9DD/0x0050CB13, 0x005264A3, 0x005265DA, 0x00536857/0x005368B9, 0x0053FB63, 0x005449AE, and 0x0061A36E.

The load constructor's third argument selects the required mode. options.ini is loaded with mode 1 at several sites, including 0x00401D10 and 0x00406ED7.

Option names and consumers¶

Known option names and sections include:

Name / section	Consumer
`LOD` / `Graphics Options`	LOD bias and shape selection
`MaxLights`	render lighting
`EffectLOD`	effect detail
`Compositing`	render compositing
`Sound Options`	audio settings
`Network Options`	connection defaults
`DefaultConnection`	network selection
`allowzoom`	zoom eligibility
`[server] allowed*`	server-side masks (hex)

The option registry is the schema the UI and the file writer share. A key that is not in the registry is still preserved as raw text when the file is rewritten, but it has no typed normalization or game binding.

Invariants and failure modes¶

The file is rewritten from the in-memory tree; manual edits do not survive an automatic save.
The loader reads the last duplicate key in a section.
Mode 1 requires a non-empty tree; an empty file asserts rather than silently loading defaults.
The dirty flag and path must both be set for a save to write anything.
The LOD gosScript registration is dead code; do not treat the four getter/setter pairs as a live control path.
LOD bias changes LOD selection, not the cull radius.
Hex values are written lowercase without a 0x prefix.
Float values are written with six decimal places.

Key entry points¶

VA	Detail	What it does
`0x0040DCA0`	ini	config-file load constructor
`0x0040E4A0`	ini	save the dirty tree
`0x0040E450`	ini	serialize one section
`0x0040ECC0`	ini	look up a named entry
`0x0040EDA0`	ini	look up or create a section
`0x00411A10`	ini	find a key node
`0x00411B00`	ini	create a key node
`0x00411C40`	ini	set a key value
`0x00411D60`	options	bind a key to a global
`0x00411DC0`	options	write a value back
`0x00406ED7`	options	options.ini registry/load/save
`0x004BC290`	options	LOD registration (dead gos path)
`0x004BC4A0`	options	LOD teardown write-back
`0x006FC4D0`	ini	raw file read
`0x0041DEE0`	ini	parse into the tree
`0x0041DE80`	ini	open the writer
`0x0041DEC0`	ini	close the writer

Details¶

Detail	VAs	Responsibility
options	8	options.ini load/save, option registry, and LOD bias persistence.
ini	5	Generic config-file tree, section/key lookup, and serialization.

Coverage¶

All 13 classified VAs are in the MW4Mercs.exe index, which lists role, size, source, and evidence.