Engine Stealth Fuel Toggle Reference

Engine Stealth Fuel Toggle Reference

Source provenance: checked 2026-06-21 against stable master@0139a346, Arma 2 OA 1.64, source mission Missions/[55-2hc]warfarev2_073v48co.chernarus.

The Engines module is the "STEALTH ON" / "STEALTH OFF" vehicle fuel toggle under Client/Module/Engines. The live source path is small but stateful: eligible tanks and wheeled APCs receive an Engine event handler and a STEALTH ON action, the stop action forces the engine off, the event handler drains fuel to zero after saving the old fuel value, and the start action restores that saved fuel (Client/Functions/Client_BuildUnit.sqf:417-418; Client/Module/Engines/Stopengine.sqf:2-7; Client/Module/Engines/Engine.sqf:3-11; Client/Module/Engines/Startengine.sqf:2-7).

Entry Points

Source surface	What the current source does	Evidence
Purchased player vehicles	After player vehicle construction, any vehicle that is Tank or Wheeled_APC receives an Engine event handler executing Client\Module\Engines\Engine.sqf and a STEALTH ON action executing Client\Module\Engines\Stopengine.sqf. The action condition requires the target to be alive and isEngineOn _target.	Client/Functions/Client_BuildUnit.sqf:417-418
WASP extra start vehicles, west side	The west-side WASP extra start vehicle path creates a random WEST_StartVeh, then applies the same Tank / Wheeled_APC engine handler and STEALTH ON action block.	Server/Init/Init_Server.sqf:504-522
WASP extra start vehicles, east side	The east-side WASP extra start vehicle path creates a random EAST_StartVeh, then applies the same Tank / Wheeled_APC engine handler and STEALTH ON action block.	Server/Init/Init_Server.sqf:524-540
Refuel service integration	The refuel helper reads the vehicle's stopped variable before doing any refuel timing and exits with the raw hint Quit the stealth mode ! when the value is true. If it proceeds and a support remains in range, the helper eventually calls setFuel 1.	Client/Functions/Client_SupportRefuel.sqf:8-12; Client/Functions/Client_SupportRefuel.sqf:60-79

Toggle Flow

Step	Source behavior	Evidence
STEALTH ON action	Stopengine.sqf resolves the caller's current vehicle, stores the action id in vehicle variable ID, calls EngineOn false, and sets vehicle variable stopped to true.	Client/Module/Engines/Stopengine.sqf:2-7
Engine event follow-up	Engine.sqf receives the vehicle and the new engine state. It only proceeds when vehicle variable ID exists, and only saves/drains fuel when _isOn is false.	Client/Module/Engines/Engine.sqf:3-7
Fuel save and forced shutdown state	On the engine-off event, Engine.sqf stores fuel _vehicle in vehicle variable Fuel, calls setFuel 0, adds a STEALTH OFF action pointing at Startengine.sqf. After the inner engine-off block exits, Engine.sqf clears vehicle variable ID at the outer if (!isNil "_get") level — so ID is also cleared if an engine-on event fires while ID is set (no fuel-save path runs in that case, leaving stopped=true with no STEALTH OFF action present).	Client/Module/Engines/Engine.sqf:8-11
STEALTH OFF action	Startengine.sqf resolves the caller's current vehicle, reads vehicle variable Fuel, restores it with setFuel _fuel, removes the current action id, and sets vehicle variable stopped to false.	Client/Module/Engines/Startengine.sqf:2-7

Vehicle State Keys

Vehicle variable	Writer	Reader	Practical note
ID	Stopengine.sqf stores the current action id; Engine.sqf clears it after the engine event is handled.	Engine.sqf checks whether ID exists before saving/draining fuel.	The source shape prevents ordinary engine-off events from running the fuel-save path unless Stopengine.sqf first staged an action id. Evidence: Client/Module/Engines/Stopengine.sqf:4-5; Client/Module/Engines/Engine.sqf:5-11.
Fuel	Engine.sqf stores the current fuel value only inside the _isOn == false branch.	Startengine.sqf reads Fuel and immediately passes it to setFuel.	There is no fallback value in Startengine.sqf if a future source change lets the start action run without a stored Fuel value. Evidence: Client/Module/Engines/Engine.sqf:7-10; Client/Module/Engines/Startengine.sqf:4-5.
stopped	Stopengine.sqf writes true; Startengine.sqf writes false.	Client_SupportRefuel.sqf reads stopped before starting the refuel flow.	The current refuel guard is checked at entry, before the refuel timing loop; the loop later refuels only if support remained in range. Evidence: Client/Module/Engines/Stopengine.sqf:7; Client/Module/Engines/Startengine.sqf:7; Client/Functions/Client_SupportRefuel.sqf:8-9,60-79.

All three module variables above are written with two-argument setVariable calls in the current source. Do not treat Fuel, ID, or stopped as intentionally published object state unless a future code change adds an explicit publication path and then smoke-tests owner changes, refuel service behavior, and start/stop actions (Client/Module/Engines/Stopengine.sqf:5,7; Client/Module/Engines/Engine.sqf:8,11; Client/Module/Engines/Startengine.sqf:7). For Arma locality, compare the missing public argument against Bohemia's setVariable reference.

The mission variable name "stopped" is separate from the Arma stopped command used by AI and travel diagnostics elsewhere. Engine-stealth writers/readers are the Stopengine.sqf, Startengine.sqf and Client_SupportRefuel.sqf variable accesses above; unrelated command/state-string hits include Client/GUI/GUI_Menu_Tactical.sqf:408, Client/Functions/Client_DiagnosePlayerAI.sqf:197-199 and Server/AI/Commander/AI_Commander.sqf:252-255.

Smoke Targets

Check	Expected source-backed result	Evidence
Purchased tank or wheeled APC action appears only while alive and engine-on.	The purchased-vehicle attach block gates on Tank / Wheeled_APC and the action condition requires alive _target &&(isEngineOn _target).	Client/Functions/Client_BuildUnit.sqf:417-418
STEALTH ON stages the engine-off fuel-drain path.	The stop action stores ID, calls EngineOn false and marks stopped=true; the Engine EH then saves Fuel, calls setFuel 0 and adds STEALTH OFF.	Client/Module/Engines/Stopengine.sqf:5-7; Client/Module/Engines/Engine.sqf:5-10
STEALTH OFF restores fuel and clears the refuel guard.	The start action reads Fuel, calls setFuel _fuel, removes the current action and marks stopped=false; refuel exits only when stopped is true.	Client/Module/Engines/Startengine.sqf:4-7; Client/Functions/Client_SupportRefuel.sqf:8-9
WASP extra start vehicles keep the same attach path.	West and East extra start vehicles both run the Tank / Wheeled_APC Engine EH and STEALTH ON action attach during server init.	Server/Init/Init_Server.sqf:504-522; Server/Init/Init_Server.sqf:524-540

Maintenance Notes

If you touch...	Keep this invariant	Evidence
Vehicle construction or start vehicles	Preserve both runtime edges: purchased tanks/wheeled APCs and WASP extra start vehicles currently attach the engine handler/action.	Client/Functions/Client_BuildUnit.sqf:417-418; Server/Init/Init_Server.sqf:504-522; Server/Init/Init_Server.sqf:524-540
Fuel restore behavior	Keep the saved-fuel and restored-fuel paths paired; Engine.sqf writes Fuel, and Startengine.sqf reads it before restoring the vehicle fuel value.	Client/Module/Engines/Engine.sqf:8-10; Client/Module/Engines/Startengine.sqf:4-5
Refuel service	Keep the stealth/refuel contract explicit. The service path currently blocks when stopped is true, then uses its normal support-range loop and final setFuel 1 behavior.	Client/Functions/Client_SupportRefuel.sqf:8-12; Client/Functions/Client_SupportRefuel.sqf:60-79

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