ai_relationship
From Valve Developer Community
ai_relationship is a point entity available in all Source games. It sets a relationship type between two parties. These parties can be an NPC, an NPC class, or the player(s).
Confirm:Relationships determine if something can damage another thing. (Antlions could be an exception...)
Dispositions:
- Error (D_ER): Rarely, a problem can occur and result in this disposition. NPCs will probably behave similar to Neutral.
- Hate (D_HT): Considers the target an enemy/enemies and will attack.
- Fear (D_FR): Avoids the target. Headcrabs run away without attacking. Metropolice attacks. Rebels avoid without attacking, and cannot be commanded. Zombies will occasionally also swipe at the target as if it is in their flight path, but these swipes will afflict no damage to player, unless the zombie has been attacked.
- Like (D_LI): Will not attack the target. Rebels follow automatically, and can be commanded. The player's weapon will play lowering animations when looking at the target. Zombies will remain still and only turn to face the target.
- Neutral (D_NU): Will not attack. Rebels avoid player apologetically, and cannot be commanded. Zombies will remain still and only turn to face the target.
Relationships are not limited to NPCs. Some objects (CBaseCombatCharacter
) can also have relationships.

In code, it is represented by class
CAI_Relationship
, defined in ai_relationship.cpp
.
Contents
Flags
- 1: Notify subject of target's location
- 2: Notify target of subject's location
Keyvalues
- Subject(s) (subject)
<target_name_or_class>
- The targetname or classname of the NPCs whose disposition will change.
- Subject Class (subjectclass)
<classname>
(New with Alien Swarm) - As above, for classnames only.
- Target(s) (target)
<target_name_or_class>
- The targetname or class name of the NPCs about whom the subject(s) will change their disposition towards.
Tip:Use
!player
for the player. - Target Class (targetclass)
<classname>
(New with Alien Swarm) - As above, for classnames only.
- Disposition (disposition)
<choices>
- The way the subject(s) should feel about the target(s)
- Hate
- Fear
- Like
- Neutral
- Radius for subject (radius)
<float>
- Only NPCs within this distance of the entity will have their dispositions changed.
- Disposition Priority (rank)
<integer>
- How much the subject(s) should Like/Hate/Fear the target(s). Higher priority = stronger feeling.
- Start Active (StartActive)
<boolean>
- Apply this relationship as soon as the entity spawns?
- Reciprocal (Reciprocal)
<boolean>
- Make the new disposition apply to the targets as well as the subjects.
Base:
- Classname (classname)
<string>
- The classname defines the type of entity. Classnames can be changed using
AddOutput
, which will influence how the engine deals with the entity in certain circumstances. - Name (targetname)
<string>
- The name that other entities refer to this entity by.
- Global Entity Name (globalname)
<string>
- Name by which this entity is linked to another entity in a different map. When the player transitions to a new map, entities in the new map with globalnames matching entities in the previous map will have the previous map's state copied over their state.
- Parent (parentname)
<targetname>
- Specifies a movement parent. An entity will maintain its initial offset from its parent. An attachment point can be added to the end of the name, separated by a comma. Every entity can be parented, even point entities. Entities which are parented will be forced to transition to the next map, such as from a
trigger_transition
. Some entities which aren't intended to be parented may not function correctly.phys_constraint
can be used as a workaround to parenting. - Origin (X Y Z) (origin)
<coordinates>
- The position of this entity's center in the world. Rotating entities typically rotate around their origin.
- Pitch Yaw Roll (X Y Z) (angles)
<angle>
- This entity's orientation in the world. Pitch is rotation around the Y axis, yaw is the rotation around the Z axis, roll is the rotation around the X axis.
Note:This works on brush entities, although Hammer doesn't show the new angles.
- Flags (spawnflags)
<integer>
- Toggles features of an entity, its specific number is determined by the combination of flags added.
- Response Contexts (ResponseContext)
<string>
- Pre-defined response system contexts for this entity. Format is
key:value,key:value,...
. Contexts may be filtered. - Effects (effects)
<integer>
!FGD - Combination of effect flags to use.
- Local Time (ltime)
<float>
!FGD - The local time of the entity, independent of the global clock. Used mainly for physics calculations.
- Next Think (nextthink)
<float>
!FGD - Amount of time before the entity thinks again.
- Hammer ID (hammerid)
<integer>
!FGD - The entity's Hammer ID. Mainly used by plugins and debugging commands, such as
ent_keyvalue
. Can be manually assigned with the "hammerid" or "id" keyvalue. Entities spawned at run-time are not assigned any Hammer ID. - Disable for Xbox 360 (disableX360)
<boolean>
(New with Left 4 Dead 2) !FGD - If Yes, disables this entity on the Xbox 360 version of Source.
- Entity Scripts (vscripts)
<scriptlist>
(New with Left 4 Dead 2) - Space delimited list of VScript files (without file extension) that are executed after all entities have spawned. The scripts are all executed in the same script scope, later ones overwriting any identical variables and functions.
- Script think function (thinkfunction)
<string>
(New with Left 4 Dead 2) - Name of a function in this entity's script which will be called automatically every 100 milliseconds (ten times a second) for the duration of the script. It can be used to create timers or to simulate autonomous behavior. The return value (if present) will set the time until the next call. Try to avoid expensive operations in this function, as it may cause performance problems.
- Lag Compensation (LagCompensate)
<boolean>
(New with Left 4 Dead 2) !FGD - Set to Yes to lag compensate this entity. Should be used very sparingly!
- Is Automatic-Aim Target (is_autoaim_target)
<boolean>
(New with Counter-Strike: Global Offensive) !FGD - If set to 1, this entity will slow down aiming movement for consoles and joystick controllers when the entity is under the crosshairs.
Inputs
-
ApplyRelationship
- Apply relationship changes. This will change all subject entities' relationships to all target entities.
Note:Once you fire
ApplyRelationship
, the entity is on until you send aDisable
orRevertRelationship
input. During the time any entities that spawn who match the subject or target names will be affected.Warning: Unpredictable results may occur when two ai_relationship entities refer to the same set or subset of target or subject entities. This situation should be avoided.
-
RevertRelationship
- Revert relationship changes. This will return the relationship to what it was at the time the
ApplyRelationship
input was called (or when this ai_relationship was spawned if Start Active is set). -
RevertToDefaultRelationship
- Revert relationship changes to the default relationship, which may have changed since this ai_relationship was applied. This returns control of the entity relationship to the code.
Base:
-
Kill
- Removes this entity and any entities parented to it from the world.
-
KillHierarchy
- Functions the same as
Kill
, although this entity and any entities parented to it are killed on the same frame. -
SetParent
<string>
- Move with this entity. See Entity Hierarchy (parenting).
-
SetParentAttachment
<string>
- Change this entity to attach to a specific attachment point on its parent. The entity will teleport so that the position of its root bone matches that of the attachment. Entities must be parented before being sent this input.
-
SetParentAttachmentMaintainOffset
<string>
- As above, but without teleporting. The entity retains its position relative to the attachment at the time of the input being received.
-
ClearParent
- Removes this entity from the the movement hierarchy, leaving it free to move independently.
-
AddOutput
<string>
- Evaluates a keyvalue/output on this entity.
Format:<key> <value>
Format:<output name> <targetname>:<inputname>:<parameter>:<delay>:<max times to fire, -1 means infinite>
-
FireUser1
toFireUser4
- Fire the
OnUser
outputs; see User Inputs and Outputs. -
Use
!FGD - Same as a player invoking +use; may not do anything. Can also be invoked by creating an output that does not specify an input.
This input is not included in Valve's FGDs. -
DispatchEffect
<string>
!FGD - Dispatches a special effect from the entity's origin. Removed and replaced entirely by the particle system since
.
-
DispatchResponse
<string>
!FGD - Dispatches a response to the entity. See Response and Concept.
-
AddContext
<string>
- Adds to the entity's list of response contexts. Format is
<key>:<value>
. -
RemoveContext
<string>
- Remove a context from this entity's list. The name should match the key of an existing context.
-
ClearContext
<string>
- Removes all contexts from this entity's list.
-
RunScriptFile
<script>
(New with Left 4 Dead 2) - Execute a VScript file from disk, without file extension. The script contents are merged with the script scope of the receiving entity.
-
RunScriptCode
<string>
(New with Left 4 Dead 2) - Execute a string of VScript source code in the scope of the entity receiving the input. String quotation may be needed when fired via console.
Bug: In
, the code is executed in the script scope of the entity that fires the output, not the one receiving the input.
Warning: Never try to pass string parameters to a script function with this input. It will corrupt the VMF structure because of the nested quotation marks, which then must be removed manually with a text editor.
-
CallScriptFunction
<string>
(New with Left 4 Dead 2) !FGD - Execute a VScript function in the scope of the receiving entity.
-
SetLocalOrigin
<coordinates>
(New with Portal 2) !FGD - Send this entity to a spot in the map. If the entity is parented to something, it will be offset from the parent by this amount.
-
SetLocalAngles
<angles>
(New with Portal 2) !FGD - Set this entity's angles.
Outputs
Base:
-
OnUser1
toOnUser4
- These outputs each fire in response to the firing of the like-numbered
FireUser1
toFireUser4
Input; see User Inputs and Outputs.