ai_sound is a point entity available in all Source games. This entity makes abstract sounds or smells that can be sensed by NPCs, but not by the player. This can be used to cause reactions in nearby NPCs. An entity called
soundent appears to help with managing AI sounds when the game runs.
In code, it is represented by class
CAISound, defined in
- Volume (volume)
- How far away this sound can be heard. This is a radius.
- Duration (duration)
- How long the sound persists each time it plays.
- Sound Type (soundtype)
- The type of sound or smell will determine the reaction of NPCs that sense it. Some of these are not in the FGD, so their associated number must be typed manually.
Literal Value Description 1 Combat: Will cause most NPCs to become alert 2 World: Will cause most NPCs to become alert 4 Player: Feign player audible 8 Danger: Will cause most NPCs to move away from the position of the sound 16 Bullet Impact 32 Carcass 64 Meat 128 Garbage 256 Thumper: causes antlions to run away briefly 512 !FGD Bugbait: get nearby antlions' attention 1024 !FGD Physics Danger: Scares off
2048 !FGD Sniper Danger: Scares
npc_snipers into their hole
4096 Move Away: Pushes away
8192 !FGD Player Vehicle: Makes NPCs hear the player & makes
npc_metropoliceturn towards the sound (only used by
16384 Player Companion Readiness: Low 32768 Player Companion Readiness: Medium 65536 Player Companion Readiness: High
- Additional sound context (optional) (soundcontext)
- Optional settings specifying such things as who can or cannot hear the sound. Many of these are not in the FGD and some of them have not been fully tested.
Literal Value Description 1048576 !FGD Sound is from Sniper 2097152 !FGD Gunfire (use with combat sound type) 4194304 !FGD Mortar (pending explosion) 8388608 Only Combine hear/smell 16777216 !FGD React to source (faces the ai_sound instead of location proxy) 33554432 !FGD Explosion (use with combat sound type) 67108864 Exclude Combine (Combine don't hear/smell) 134217728 !FGD Danger approach (react with danger if you see the ai_sound, just face if otherwise, shouldn't work with location proxy) 268435456 !FGD Only allies (npc_citizen, etc.) hear/smell
- Location Proxy (locationproxy)
- If you specify an entity here, the sound will be made at that entity's location (
!playeris an option).
- Classname (classname)
- 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)
- The name that other entities refer to this entity by.
- Global Entity Name (globalname)
- 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)
- 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_constraintcan be used as a workaround to parenting.
- Origin (X Y Z) (origin)
- The position of this entity's center in the world. Rotating entities typically rotate around their origin.
- Pitch Yaw Roll (X Y Z) (angles)
- 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)
- Toggles features of an entity, its specific number is determined by the combination of flags added.
- Response Contexts (ResponseContext)
- Pre-defined response system contexts for this entity. Format is
key:value,key:value,.... Contexts may be filtered.
- Effects (effects)
- Combination of effect flags to use.
- Local Time (ltime)
- The local time of the entity, independent of the global clock. Used mainly for physics calculations.
- Next Think (nextthink)
- Amount of time before the entity thinks again.
- Hammer ID (hammerid)
- 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.
- Deprecated. Insert a sound in the AI sound list at a specified volume (1-100) which influences detection radius.
- Make the Sound.
- Removes this entity and any entities parented to it from the world.
- Functions the same as
Kill, although this entity and any entities parented to it are killed on the same frame, being marginally faster than
- Move with this entity. See Entity Hierarchy (parenting).
- 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.
- As above, but without teleporting. The entity retains its position relative to the attachment at the time of the input being received.
- Removes this entity from the the movement hierarchy, leaving it free to move independently.
- Evaluates a keyvalue/output on this entity.
<output name> <targetname>:<inputname>:<parameter>:<delay>:<max times to fire, -1 means infinite>
- Fire the
OnUseroutputs; see User Inputs and Outputs.
- 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.
- Dispatches a special effect from the entity's origin. Removed and replaced entirely by the particle system since .
- Dispatches a response to the entity. See Response and Concept.
- Adds to the entity's list of response contexts. Format is
- Remove a context from this entity's list. The name should match the key of an existing context.
- Removes all contexts from this entity's list.
- These outputs each fire in response to the firing of the like-numbered
FireUser4Input; see User Inputs and Outputs.