Npc headcrab

GoldSrc

Half-Life: Source

Source Engine

Source 2

edit

Class hierarchy
CHeadcrab ↳CBaseHeadcrab ↳CAI_BaseNPC ↳CBaseCombatCharacter ↳CBaseFlex ↳CBaseAnimatingOverlay ↳CBaseAnimating ↳CBaseEntity
npc_headcrab.cpp

npc_headcrab is a point entity available in Half-Life 2 series and Black Mesa. These are the classic, slow-moving headcrabs. They attack by jumping at the player's head and inflict a nominal amount of damage. Almost any weapon can dispatch them easily.

Commonly found attached to a zombie host body, they will detach if that host is sufficiently damaged below the head.

There are several other headcrab variants and associated zombie types.

See also env_headcrabcanister which is a mortar shell containing a payload of headcrabs. The mortar shell inflicts damage within a radius of where it lands and releases headcrabs after impact. Triggers and entity options offer control over impact damage and when the headcrabs are released, among other options.

Placement Tip:Classic headcrabs can be paired with their fast-moving or poisonous relatives to make it more interesting.

Placement Tip:Avoid the cliche of placing headcrabs in vents; they would likely be more of an annoyance than an improvement on gameplay.

Bug:If a headcrab is burrowed, using the sethealth 0 input on it will not kill the headcrab. The input gets ignored and the headcrab's health doesn't change. Despite that, such headcrab can still unburrow and behave normally. The kill input can still kill the headcrab but it will disappear instantly.  (tested in: Half-Life 2)

Note:Some keyvalues, spawnflags, effect flags, inputs, or outputs might not affect an NPC, based on the functionality and coding of the NPC.

In code, it is represented by theCHeadcrabclass, defined in thenpc_headcrab.cppfile.

Dedicated Console Variables

sk_headcrab_health <int>

A headcrab's spawn health.

sk_headcrab_melee_dmg <int>

Melee damage.

g_debug_headcrab <bool>

Toggle headcrab debugging.

sk_headcrab_min_jump_dist <int>

Headcrab min jump distance. Only in Black Mesa 2012.

sk_headcrab_max_jump_dist <int>

Headcrab max jump distance. Only in Black Mesa 2012.

sv_headcrab_can_latch_on_player <bool>

Toggles headcrab's ability to attach player's head (if player catches it with head). Only in Black Mesa 2012. Requires this texture to display properly as the texture has been removed.

Keyvalues

Parentname:

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.

BaseHeadcrab:

Start burrowed (startburrowed) <boolean>

Should this npc start burrowed? Will unburrow via input or if an enemy gets near.

Note:If a headcrab is burrowed, it cannot be damaged. Use Kill input if needing to remove such headcrab.

Flags

Start hidden : [65536]

Start hanging from ceiling : [131072]

Inputs

Burrow  !FGD

Burrow. If no burrow points within 512 units, does nothing.

BurrowImmediate  !FGD

Burrow immediate.

Unburrow  !FGD

Unburrow.

StartHangingFromCeiling

Start hanging from ceiling.

DropFromCeiling

Drop if hanging from ceiling.

Parentname:

SetParent <stringRedirectInput/string>

Move with this entity. See Entity Hierarchy (parenting).

SetParentAttachment <stringRedirectInput/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 <stringRedirectInput/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.

Outputs

BaseNPC Outputs

OnDamaged Fired when this NPC takes damage (!activator is the damage inflictor). OnDamagedByPlayer Fired when this NPC is hurt by a player (!activator is the attacker or vehicle driver [if friendly fire]). OnDamagedByPlayerSquad Fired when this NPC is hurt by a player OR by one of the player's squadmates (!activator is the attacker or vehicle driver [if friendly fire]). OnDeath Fired when this NPC is killed (!activator is the killer). OnDenyCommanderUse Fired when this NPC has refused to join the player's squad. OnForcedInteractionAborted Fired when the NPC aborts a forced interaction for some reason (target NPC died, couldn't be pathed to, etc.). OnForcedInteractionStarted Fired when the NPC starts a forced interaction. OnForcedInteractionFinished "NPCs in actbusies can no longer perform dynamic interactions." Todo: What does this mean? OnHalfHealth Fired when this NPC reaches half of its maximum health. OnHearCombat Fired when this NPC hears combat sounds. OnHearPlayer Fired when this NPC hears the player. OnHearWorld Fired when this NPC hears a sound (other than combat or the player). OnFoundEnemy <targetname*RedirectOutput/ehandle> Fired when this NPC establishes line of sight to its enemy. OnLostEnemy Fired when this NPC loses its enemy. Usually due to the enemy being killed/removed, or because this NPC has selected a newer, more dangerous enemy. OnLostEnemyLOS Fired when this NPC loses line of sight to its enemy. OnFoundPlayer <targetname*RedirectOutput/ehandle> Fired when this NPC establishes line of sight to its enemy, and that enemy is a player. OnLostPlayer Fired when this NPC loses its enemy, and that enemy was a player. Usually due to the enemy being killed/removed, or because this NPC has selected a newer, more dangerous enemy. OnLostPlayerLOS Fired when this NPC loses line of sight to its enemy, and that enemy is a player. OnSleep Fired when this NPC enters a sleep state. OnWake Fired when this NPC comes out of a sleep state.

See also

• env_headcrabcanister