Arma 3: Event Handlers

Introduction

An event handler (abbreviated to EH) allows you to automatically monitor and then execute custom code upon particular events being triggered.

These event handlers relate to commands such as: addEventHandler, removeEventHandler, removeAllEventHandlers.

General MP Note

As opposed to OFP event handlers, a respawned unit retains the EHs it had before, so it is no longer required to re-add EHs after respawning.

The MP event handlers "MPHit", "MPKilled" and "MPRespawn" have to be assigned to the object by using addMPEventHandler.

Event Scripts

See also: Event Scripts for special event triggered scripts.

Event Handler List

AnimChanged

Triggered every time a new animation is started. It can be assigned to a remote unit but will only fire on the PC where the actual addEventHandler command was executed.

Passed array: [unit, anim]

• unit: Object - Object the event handler is assigned to
  
• anim: String - Name of the anim that is started
  

AnimDone

Triggered every time an animation is finished. It can be assigned to a remote unit but will only fire on the PC where the actual addEventHandler command was executed.

Passed array: [unit, anim]

• unit: Object - Object the event handler is assigned to
  
• anim: String - Name of the anim that has been finished
  

AnimStateChanged

Triggered every time an animation state changes. Unlike AnimChanged and AnimDone, it is triggered for all animation states in a sequence. It can be assigned to a remote unit but will only fire on the PC where the actual addEventHandler command was executed.

Passed array: [unit, anim]

• unit: Object - Object the event handler is assigned to
  
• anim: String - Name of the anim that has been started
  

ControlsShifted

Triggers when controls of vehicle are shifted (pilot->co-pilot, co-pilot->pilot). Works for both, "Take" and "Release" controls actions. Event only triggers on PC where vehicle is local and EH was added.

NOTE: If helicopter is local to the server and co-pilot takes controls, the helicopter changes locality to co-pilot PC. This means that if "ControlsShifted" EH was added on both server and client, "Take Controls" action will trigger EH on the server PC, but subsequent co-pilot "Release Controls" action will trigger it on co-pilot's PC.

Passed array: [vehicle, newController, oldController]

• vehicle: Object - Vehicle which controls were shifted.
  
• newController: Object - Unit who controls vehicle after this event.
  
• oldController: Object - Unit who controled vehicle before this event.
  

Dammaged

Triggered when the unit is damaged. In ArmA works with all vehicles not only men like in OFP. It can be assigned to a remote vehicle but will only fire on the PC where the actual addEventHandler command was executed.

(If simultaneous damage occured (e.g. via grenade) EH might be triggered several times.)

Passed array: [unit, selectionName, damage]

• unit: Object - Object the event handler is assigned to
  
• selectionName: String - Name of the selection where the unit was damaged
  
• damage: Number - Resulting level of damage

Engine

Triggered when the engine of the unit is turned on/off.

Global.

Passed array: [vehicle, engineState]

• vehicle: Object - Vehicle the event handler is assigned to
  
• engineState: Boolean - True when the engine is turned on, false when turned off

EpeContact

Triggered when object collision (PhysX) is in progress. It can be assigned to a remote vehicle but will only fire on the PC where the actual addEventHandler command was executed.

Passed array: [object1, object2, select1, select2, force]

• object1: Object - Object with attached handler.
  
• object2: Object - Object which is colliding with object1.
  
• select1: String - Selection of object1 which is colliding - not in use at this moment, empty string is always returned.
• select2: String - Selection of object2 which is colliding - not in use at this moment, empty string is always returned.
• force: Number - Force of collision.

EpeContactEnd

Triggered when object collision (PhysX) ends. It can be assigned to a remote vehicle but will only fire on the PC where the actual addEventHandler command was executed.

Passed array: [object1, object2, select1, select2, force]

• object1: Object - Object with attached handler.
  
• object2: Object - Object which is colliding with object1.
  
• select1: String - Selection of object1 which is colliding - not in use at this moment, empty string is always returned.
• select2: String - Selection of object2 which is colliding - not in use at this moment, empty string is always returned.
• force: Number - Force of collision.

EpeContactStart

Triggered when object collision (PhysX) starts. It can be assigned to a remote vehicle but will only fire on the PC where the actual addEventHandler command was executed.

Passed array: [object1, object2, select1, select2, force]

• object1: Object - Object with attached handler.
  
• object2: Object - Object which is colliding with object1.
  
• select1: String - Selection of object1 which is colliding - not in use at this moment, empty string is always returned.
• select2: String - Selection of object2 which is colliding - not in use at this moment, empty string is always returned.
• force: Number - Force of collision.

Explosion

Triggered when a vehicle or unit is damaged by a nearby explosion. It can be assigned to a remote vehicle but will only fire on the PC where the actual addEventHandler command was executed.

Passed array: [vehicle, damage]

• vehicle: Object - Object the event handler is assigned to
• damage: Number - Damage inflicted to the object

Fired

Triggered when the unit fires a weapon.
This EH will not trigger if a unit fires out of a vehicle. For those cases an EH has to be attached to that particular vehicle.

Global.

Passed array: [unit, weapon, muzzle, mode, ammo]
OA b1.54.73642 : [unit, weapon, muzzle, mode, ammo, magazine, projectile]

• unit: Object - Object the event handler is assigned to
  
• weapon: String - Fired weapon
  
• muzzle: String - Muzzle that was used
  
• mode: String - Current mode of the fired weapon
  
• ammo: String - Ammo used
  
• magazine: String - magazine name which was used
  
• projectile: Object - Object of the projectile that was shot

FiredNear

Triggered when a weapon is fired somewhere near the unit or vehicle.
It is also triggered if the unit itself is firing.

Global.

(Exception(s): the Throw weapon wont broadcast the FiredNear event)

Passed array: [unit, firer, distance, weapon, muzzle, mode, ammo]

• unit: Object - Object the event handler is assigned to
• firer: Object - Object which fires a weapon near the unit
• distance: Number - Distance in meters between the unit and firer (max. distance ~69m)
• weapon: String - Fired weapon
• muzzle: String - Muzzle that was used
• mode: String - Current mode of the fired weapon
• ammo: String - Ammo used

Fuel

Triggered when the unit's fuel status changes between completely empty / not empty (only useful if the event handler is assigned to a vehicle).

Global.

Passed array: [vehicle, fuelState]

• vehicle: Object - Vehicle the event handler is assigned to
  
• fuelState: Boolean - 0 when no fuel, 1 when the fuel tank is full

Gear

Triggered when the unit lowers/retracts the landing gear (only useful if the event handler is assigned to is a member of the class "Plane").

Global. Passed array: [vehicle, gearState]

• vehicle: Object - Vehicle the event handler is assigned to
  
• gearState: Boolean - True when the gear is lowered, false when retracted

GetIn

Triggers when a unit enters a vehicle. It can be assigned to a remote vehicle but will only fire on the PC where the actual addEventHandler command was executed. This EH is neither triggered upon a change of positions within the same vehicle nor by the moveInXXXX commands. However it is triggered by a "GetInXXXX" action.

Passed array: [vehicle, position, unit]

• vehicle: Object - Vehicle the event handler is assigned to
• position: String - Can be either "driver", "gunner", "commander" or "cargo"
• unit: Object - Unit that entered the vehicle

In vehicles with multi-turret setup, entering any turret will show "gunner" for position. You can get the actual turret information from the unit itself: _heli addEventHandler ["GetIn", { hint str assignedVehicleRole (_this select 2); }];

GetOut

Triggers when a unit gets out from a vehicle. It can be assigned to a remote vehicle but will only fire on the PC where the actual addEventHandler command was executed. This EH is triggered by both the moveOut command and by "GetOut" action.

Passed array: [vehicle, position, unit]

• vehicle: Object - Vehicle the event handler is assigned to
• position: String - Can be either "driver", "gunner", "commander" or "cargo"
• unit: Object - Unit that left the vehicle

In vehicles with multi-turret setup, exiting any turret will show "gunner" for position. You can get the actual turret information from the unit itself: _heli addEventHandler ["GetOut", { hint str assignedVehicleRole (_this select 2); }];

HandleDamage

Triggers when the unit is damaged and fires for each damaged selection separately. Works with all vehicles. This EH can accept a remote unit as argument however it will only fire when the unit is local to the PC this event handler was added on. For example, you can add this event handler to one particular vehicle on every PC. When this vehicle gets hit, only EH on PC where the vehicle is currently local will fire.

If code provided returns a numeric value, this value will overwrite the default damage of given selection after processing. Return value of 0 will make the unit invulnerable if damage is not scripted in other ways (i.e using setDamage and/or setHit for additional damage handling). If no value is returned, the default damage processing will be done. This allows for safe stacking of this event handler. Only the return value of the last added "HandleDamage" EH is considered.

Passed array: [unit, selectionName, damage, source, projectile]

• unit: Object - Object the event handler is assigned to.
• selectionName: String - Name of the selection where the unit was damaged. "" for over-all structural damage, "?" for unknown selections.
• damage: Number - Resulting level of damage for the selection.
• source: Object - The source unit that caused the damage.
• projectile: String - Classname of the projectile that caused inflicted the damage. ("" for unknown, such as falling damage.)

Examples:

This code makes Bob invulnerable: _eh = Bob addEventHandler ["HandleDamage", {hint "IMMA INVINCIBLED!"; 0}];

This code will log damage values without interfering with default damage processing: _eh = Bob addEventHandler ["HandleDamage", {diag_log format ["T=%1 : %2", time, _this];}];

When shooting Bob once in the torso and once in the head, .RPT shows:

"T=11692.9 : [B Alpha 2-2:1,"head",0.0179969,<NULL-object>,"B_65x39_Caseless"]"
"T=11692.9 : [B Alpha 2-2:1,"",0.850484,B Alpha 1-1:1 (KK),"B_65x39_Caseless"]"
"T=11692.9 : [B Alpha 2-2:1,"",0.850484,B Alpha 1-1:1 (KK),"B_65x39_Caseless"]"
"T=11692.9 : [B Alpha 2-2:1,"head",0.0179969,B Alpha 1-1:1 (KK),"B_65x39_Caseless"]"
"T=11692.9 : [B Alpha 2-2:1,"body",0.0939217,B Alpha 1-1:1 (KK),"B_65x39_Caseless"]"
"T=11692.9 : [B Alpha 2-2:1,"hands",0.109993,B Alpha 1-1:1 (KK),"B_65x39_Caseless"]"

"T=11694.8 : [B Alpha 2-2:1,"head",0.899007,<NULL-object>,"B_65x39_Caseless"]"
"T=11694.8 : [B Alpha 2-2:1,"",0.346781,B Alpha 1-1:1 (KK),"B_65x39_Caseless"]"
"T=11694.8 : [B Alpha 2-2:1,"",1.19727,B Alpha 1-1:1 (KK),"B_65x39_Caseless"]"
"T=11694.8 : [B Alpha 2-2:1,"head",0.899007,B Alpha 1-1:1 (KK),"B_65x39_Caseless"]"

Notes:

• Each "HandleDamage" event shows the current damage from the damage source, NOT cumulative or the current "damage level" (health) of the target unit.
• Multiple "HandleDamage" event handlers can be added to the same unit, however only the damage return value from the last added EH will be relayed to the game engine.
• You can save the last event as timestamp (diag_tickTime) onto the unit, as well as the current health of the unit/its selections, with setVariable and query it on each "HandleDamage" event with getVariable to define a system how to handle the "HandleDamage" event.
• "HandleDamage" will continue to trigger even if the unit is already dead.
• "HandleDamage" is persistent. If you add it to the player object, it will continue to exist after player respawned.
• "HandleDamage" can trigger "twice" per damage event. Once for direct damage, once for indirect damage (explosive damage). This can happen even in the same frame, but is unlikely:

// first HandleDamage event - direct damage by sabot hit onto an infantry unit
1081.55,[TargetUnit,"",6426.05,SourceUnit,"Sh_120_SABOT"]
1081.55,[TargetUnit,"head_hit",441.609,SourceUnit,"Sh_120_SABOT"]
1081.55,[TargetUnit,"body",333.333,SourceUnit,"Sh_120_SABOT"]
1081.55,[TargetUnit,"hands",533.333,SourceUnit,"Sh_120_SABOT"]
1081.55,[TargetUnit,"legs",533.333,SourceUnit,"Sh_120_SABOT"]

// second HandleDamage event - indirect damage by the impact - maybe force/friction applied to the unit body
1081.59,[TargetUnit,"",2.24228,TargetUnit,""]
1081.59,[TargetUnit,"head_hit",0.89672,TargetUnit,""]
1081.59,[TargetUnit,"body",3.3113,TargetUnit,""]
1081.59,[TargetUnit,"hands",3.74862,TargetUnit,""]
1081.59,[TargetUnit,"legs",10,TargetUnit,""]

Link to explanation Celery's explanation

HandleHeal

Triggered when unit starts to heal (player using heal action or AI heals after being ordered). Triggers only on PC where EH is added and unit is local. If code returns false, engine side healing follows. Return true if you handle healing in script, use AISFinishHeal to tell engine that script side healing is done. See also lifeState and setUnconscious commands.

Passed array: [unit, healer, healercanheal]

• unit: Object
• healer: Object
• healercanheal: Boolean - true when healer is corpsman

Hit

Triggered when the unit is hit/damaged.

Is not always triggered when unit is killed by a hit.
Most of the time only the killed event handler is triggered when a unit dies from a hit.
The hit EH will not necessarily fire if only minor damage occurred (e.g. firing a bullet at a tank), even though the damage increased.
Does not fire when a unit is set to allowDamage false.

Local.

Passed array: [unit, causedBy, damage]

• unit: Object - Object the event handler is assigned to
  
• causedBy: Object - Object that caused the damage.
  Contains the unit itself in case of collisions.
  
• damage: Number - Level of damage caused by the hit

HitPart

Runs when the object, it was added to, gets injured/damaged. It returns the position and component that was hit on the object within a nested array, this is because the model may have more than selection name for the hit component.

While you can add "HitPart" handler to a remote unit, the respectful addEventHandler command must be executed on the shooter's PC and will only fire on shooter's PC as well. Additionally, if the unit gets damaged by any means other than shooter's shooting, "HitPart" will not fire. Because of this, this event handler is most suitable for when the shooter needs feedback on his shooting, such as target practicing or hitmarker creation.

Passed array: [[target, shooter, bullet, position, velocity, selection, ammo, direction, radius, surface, direct]]

• target: Object - Object that got injured/damaged.
• shooter: Object - Unit that inflicted the damage. If injured by a vehicle impact or a fall the target itself is returned, or, in case of explosions, the null object. In case of explosives that were planted by someone (e.g. satchel charges), that unit is returned.
• bullet: Object - Object that was fired.
• position: Position3D - Position the bullet impacted (ASL).
• velocity: Vector3D - 3D speed at which bullet impacted.
• selection: Array - Array of Strings with named selection of the object that were hit.
• ammo: Array - Ammo info: [hit value, indirect hit value, indirect hit range, explosive damage, ammo class name] OR, if there is no shot object: [impulse value on object collided with,0,0,0]
• direction: Vector3D - vector that is orthogonal (perpendicular) to the surface struck. For example, if a wall was hit, vector would be pointing out of the wall at a 90 degree angle.
• radius: Number - Radius (size) of component hit.
• surface: String - Surface type struck.
• direct: Boolean - true if object was directly hit, false if it was hit by indirect/splash damage.

HitPart Sample output after DemoCharge explosion

Init

Triggered on mission start or when a vehicle is created on the fly using createVehicle.

Global.

Passed array: [unit]

• unit: Object - Object the event handler is assigned to

IncomingMissile

Triggered when a guided missile locked on the target or unguided missile or rocket aimed by AI at the target was fired.

Global.

Passed array: [unit, ammo, whoFired]

• unit: Object - Object the event handler is assigned to
  
• ammo: String - Ammo type that was fired on the unit
  
• whoFired: Object - Object that fired the weapon

Killed

Triggered when the unit is killed.

Local.

Passed array: [unit, killer]

• unit: Object - Object the event handler is assigned to
  
• killer: Object - Object that killed the unit
  Contains the unit itself in case of collisions.
  

Be careful when the killer has been a vehicle. For most cases the reference of the vehicle is the same as the effectiveCommander, yet not always. For example:

_gunner setVariable ["Variable",true];
_killer getVariable "Variable" => <null>
(gunner (vehicle _killer)) getVariable "Variable" => true

And sample debug output:

_killer => B 1-2-F:2
(gunner (vehicle _killer)) => B 1-2-F:2
((gunner (vehicle _killer)) == _killer) => false

LandedTouchDown

Triggered when a plane (AI or player) touches the ground.

Local.

Passed array: [plane, airportID]

• plane: Object - Object the event handler is assigned to
  
• airportID: Number - ID of the airport (-1 for anything else).
  

LandedStopped

Triggered when an AI pilot would get out usually. Not executed for player.

Local.

Passed array: [plane, airportID]

• plane: Object - Object the event handler is assigned to
  
• airportID: Number - ID of the airport (-1 for anything else).
  

Local

Triggered when locality of object in MP is changed.

Passed array: [localUnit, local]

• localUnit: Object - Unit for who is object local.
  
• local: Boolean - If the object is local on given computer.
  

MPHit

Triggered when the unit is hit/damaged. EH can be added on any machine and EH code will trigger globally on every connected client and server. Add it only on server because if you have 10 machines on network and add this EH to every machine, when triggered the EH code will be executed 10 x 10 = 100 times.

Is not always triggered when unit is killed by a hit. Most of the time only the Killed event handler is triggered when a unit dies from a hit. The hit EH will not necessarily fire if only minor damage occurred (e.g. firing a bullet at a tank), even though the damage increased. Can also trigger several times for an explosion (direct and indirect damage). Does not fire when a unit is set to allowDamage false. However it will fire with "HandleDamage" EH added alongside stopping unit from taking damage addEventHandler ["HandleDamage",{0}]; Will not trigger when unit is dead.

This EH must be used in conjunction with the addMPEventHandler command.

Passed array: [unit, causedBy, damage]

• unit: Object - Object the event handler is assigned to
  
• causedBy: Object - Object that caused the damage. Contains the unit itself in case of collisions.
  
• damage: Number - Level of damage caused by the hit

Coding advice:

Call a function from the MPHit EH code space, rather to define the full code in there directly. The reason is the code space will be transferred over network on each event activation - so keep the data as small as possible!

//good MyTag_Function = { //your code }; _unit addMPEventHandler ["MPHit", {_this call MyTag_Function}];

//bad _unit addMPEventHandler ["MPHit", { //your code }];

MPKilled

Triggered when the unit is killed. EH can be added on any machine and EH code will trigger globally on every connected client and server. Add it only on server because if you have 10 machines on network and add this EH to every machine, when triggered the EH code will be executed 10 x 10 = 100 times.

Passed array: [unit, killer]

• unit: Object - Object the event handler is assigned to
  
• killer: Object - Object that killed the unit
  Contains the unit itself in case of collisions.
  

Notes:

• This command must be used in conjunction with the command addMPEventHandler rather than the old command used for non MP commands.
• This event handler is triggered for a disconnecting player, if "playableAI" are disabled (by admin or description.ext), so that the playable unit dies on disconnect.

Coding advice:

Call a function from the MPKilled EH code space, rather to define the full code in there directly. The reason is the code space will be transferred over network on each event activation - so keep the data as small as possible!

//good MyTag_Function = { //your code }; _unit addMPEventHandler ["MPKilled", {_this call MyTag_Function}];

//bad _unit addMPEventHandler ["MPKilled", { //your code }];

MPRespawn

Triggered when a unit respawns.

Global.

Passed array: [unit, corpse, ...]

• unit: Object - Object the event handler is assigned to
• corpse: Object - Object the event handler was assigned to, aka the corpse/unit player was previously controlling.

Notes:

This event never triggers on server: [1]

As of OA 1.62, this command does not work as one would expect. It is only triggered on the machine where the unit it was assigned to is local. The only difference between Respawn and MPRespawn is that MPRespawn can be assigned from anywhere while Respawn requires the unit to be local.

This command must be used in conjunction with the command addMPEventHandler rather than the old command used for non MP commands.

MusicStart

Triggers when CfgMusic sound starts playing, after being executed with playMusic command.

This event handler needs to be added with addMusicEventHandler command and removed with removeMusicEventHandler. Passed array: [className, handlerID]

• className: String - CfgMusic class name of currently playing sound.
  
• handlerID: Number - EH id returned by addMusicEventHandler.
  

Example: _ehID = addMusicEventHandler ["MusicStart", {hint str _this}]; playMusic "RadioAmbient3"; //hint shows ["RadioAmbient3", 0] 0 = [] spawn {sleep 2; playMusic ""}; //stops the music after 2 seconds

MusicStop

Triggers when CfgMusic sound finished playing, after being executed with playMusic command. Note that EH will not be triggered if you force stop the music with playMusic "".

This event handler needs to be added with addMusicEventHandler command and removed with removeMusicEventHandler. Passed array: [className, handlerID]

• className: String - CfgMusic class name of currently played sound.
  
• handlerID: Number - EH id returned by addMusicEventHandler.
  

Example: _ehID = addMusicEventHandler ["MusicStop", {hint str _this}]; playMusic "RadioAmbient3"; //hint shows ["RadioAmbient3", 0] after a few seconds

Respawn

Triggered when a unit respawns.

Passed array: [unit, corpse, ...]

• unit: Object - Object the event handler is assigned to
  
• corpse: Object - Object the event handler was assigned to, aka the corpse/unit player was previously controlling.
  

PostReset

From .\functions_f\Feedback\fn_feedbackInit.sqf

//checks whether PPs were reseted by engine
BIS_EnginePPReset = false;
if (isNil {player getVariable "BIS_fnc_feedback_postResetHandler"}) then {
	player setVariable ["BIS_fnc_feedback_postResetHandler", true];
	player addeventhandler ["PostReset",{BIS_EnginePPReset = true;} ];
};

Put

Triggers when a unit puts an item in a container.

Passed array: [unit, container, item]

• unit: Object - Unit to which the event handler is assigned
  
• container: Object - The container into which the item was placed (vehicle, box, etc.)
  
• item: String - The class name of the moved item
  

Take

Triggers when a unit takes an item from a container.

Passed array: [unit, container, item]

• unit: Object - Unit to which the event handler is assigned
  
• container: Object - The container from which the item was taken (vehicle, box, etc.)
  
• item: String - The class name of the taken item
  

SoundPlayed

Something to do with your character making noises when injured or fatigued.

WeaponAssembled

Triggers when weapon gets assembled.

Global.

Passed array: [unit, weapon]

• unit: Object - Object the event handler is assigned to
  
• weapon: Object - Object of the assembled weapon.
  

WeaponDisassembled

Triggers when weapon gets disassembled.

Global.

Passed array: [unit, primaryBag, secondarybag]

• unit: Object - Object the event handler is assigned to
  
• primaryBag: Object - First backpack object which was weapon dissasembled into...
  
• secondarybag: Object - Second backpack object which was weapon dissasembled into...