feat(ai): runtime cvars for stalker rank-dispersion curve

[damiansirbu]

Summary

Adds ai_dispersion_novice_k and ai_dispersion_experienced_k CCC_Float console variables that scale the per-rank weapon-dispersion multiplier on top of vanilla's rank curve in CAI_Stalker::GetWeaponAccuracy. Defaults 1.0/1.0 produce identity scaling; vanilla behavior is bit-identical without any cvar override. A cvar write from console, user.ltx, the in-game options menu, MCM, or exec_console_cmd takes effect on every stalker NPC's next shot.

The PR is purely additive. Vanilla m_fRankDisperison, its net_Spawn assignment, and the pSettings->r_float("ranks_properties", "dispersion_*_k") LTX reads are untouched. The new code adds one block after the existing base *= m_fRankDisperison; line that applies the cvar-driven scale factor interpolated by NPC rank. DLTX patches to those LTX keys continue to work normally; the cvars compose multiplicatively on top.

The PR also wires the cvars into the "Stalkers" section of the modded exes options menu introduced by PR #523, with English and Russian translation strings.

The pattern matches the existing ai_aim_* cvar family (g_ai_aim_min_speed, g_ai_aim_min_angle, g_ai_aim_max_angle, g_aim_predict_time): file-scope globals exposed via CMD4(CCC_Float, ...) and read in per-frame AI ticks.

Use cases

Any combat-AI mod that wants runtime control over the rank-dispersion curve.

• MCM difficulty presets in modpacks that swap cvar pairs without engine knowledge.
• Per-scenario Lua tuning (e.g. a boss fight that tightens NPC aim, then restores defaults).
• Replacing the runtime-tuning use case behind Dynamic AI Aim Settings, GAMMA NPCs Faster Reactions, ReDone Combat AI, DLTX_JURASZKA. DLTX patches to those mods' LTX keys still work after this PR; the cvars apply on top.
• Difficulty scaling tied to player rank or story progression from Lua.

Cvar semantics

The cvars are SCALE factors applied on top of vanilla's rank curve:

final_factor = vanilla_curve(R) * cvar_curve(R)

cvar_curve(R) interpolates between g_ai_dispersion_novice_k (at rank 0) and g_ai_dispersion_experienced_k (at rank 100) by NPC rank. To widen low-rank dispersion, set ai_dispersion_novice_k 2.0. To tighten high-rank, set ai_dispersion_experienced_k 0.5.

Cvar naming

The cvar names match the vanilla LTX key names in game_relations.ltx [ranks_properties]. The "novice_k" name is accurate (rank 0 / novice tier) but "experienced_k" is misleading: vanilla applies that value at rank 100, which is the legend tier in Anomaly's rank scale. The cvar names preserve the LTX convention for engine-side consistency; the menu description strings clarify the actual rank tier.

Mid-session rank changes

The cvar scale layer reads Rank() per shot, so mid-session rank promotions are reflected immediately. Vanilla m_fRankDisperison stays frozen at spawn. At default cvar values this is invisible; with non-default cvars the cvar curve responds to rank changes live while the vanilla curve does not. Composition is intentional.

Files changed

Six files, 57 lines added, 0 removed.

• src/xrGame/ai/stalker/ai_stalker_fire.cpp — two new file-scope globals, 5 new lines in GetWeaponAccuracy after the vanilla base *= m_fRankDisperison;.
• src/xrGame/console_commands.cpp — two CMD4(CCC_Float, ...) entries placed next to the ai_aim_* block.
• gamedata/scripts/lua_help_ex.script — two cvar manifest entries.
• gamedata/scripts/options_modded_exes_stalkers.script — two track sliders (def 1.0, min 0.0, max 10.0, step 0.1).
• gamedata/configs/text/eng/ui_mm_modded_exes.xml — four translation strings.
• gamedata/configs/text/rus/ui_mm_modded_exes.xml — four translation strings (windows-1251 preserved).

Console usage

ai_dispersion_novice_k 1.5
ai_dispersion_experienced_k 0.5

Lua usage

function actor_on_first_update()
    exec_console_cmd("ai_dispersion_novice_k 1.5")
    exec_console_cmd("ai_dispersion_experienced_k 0.5")
end

[themrdemonized]

I dont think Rank is used normally in the engine. values per character_id is all over the place (a lot more than 100, in 10000s, some have ranges ie <rank min="1000" max="6000" />)

game_relations.ltx for ranks_propertis mentions this

; Section is not used by the game.
; However it is directly referenced in-engine.
; Removing this or its contents will crash the game.
[ranks_properties]
immunities_novice_k			= 1.0
immunities_experienced_k	= 1.0
visibility_novice_k			= 1.0
visibility_experienced_k	= 1.0
dispersion_novice_k			= 1.0
dispersion_experienced_k	= 0.8

so effectively everyone have dispersion_experienced_k = 0.8

m_fRankDisperison is ultimately used only in GetWeaponAccuracy. At the end it calls lua function which fires npc_shot_dispersion callback, there you can adjust accuracy hovewer you like. I dont see a point in this PR.

[damiansirbu]

You're right. Modded ranks in the thousands all collapse to rank_k = 1.0 and ai_dispersion_novice_k ends up dead. Closing.