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<Half-Life 2> npc_rollermine is a point entity available in the Half-Life 2 series.

Basically an artificially intelligent prop_physics, the rollermine will roll itself at the player or at any NPC (excluding Combine NPCs). Upon hitting its target, the rollermine will electrify, damage what it is touching, and bounce off. They will attach themselves to Gordon's tau-equipped buggy from Half-Life 2, and they can be dropped by Combine dropships. If an explosion occurs near them, they will briefly fly into the air before disintegrating.

In Half-Life 2: Episode One, Alyx can reprogram rollermines to make them friendly to the player. This is done by using the outputs OnAlyxStartedInteraction and OnAlyxFinishedInteraction, and ai_relationship or the SetRelationship input.

Placementtip.gif Placement Tip: These rolling metal terrors can give the player quite a fright if they come up behind him and attack. They are manufactured and used by the Combine, so remember that when placing.
Some keyvalues, flags, inputs, or outputs might not affect an NPC based on the functionality and coding of the NPC.

Dedicated Console Variables

sk_rollermine_shock <int>
To do: Add a description for this variable. (Default: 0)
sk_rollermine_stun_delay <int>
To do: Add a description for this variable. (Default: 1)
sk_rollermine_vehicle_intercept <int>
To do: Add a description for this variable. (Default: 1)



Target Path Corner <targetname>
The path_corner that this NPC will move to after spawning.
Squad Name <string>
NPCs that are in the same squad (i.e. have matching squad names) will share information about enemies, and will take turns attacking and covering each other.
Hint Group <string>
Hint groups are used by NPCs to restrict their hint-node searching to a subset of the map's hint nodes. Only hint nodes with matching hint group names will be considered by this NPC.
Hint Limit Nav <boolean>
Limits NPC to using specified hint group for navigation requests, but does not limit local navigation.
Sleep State <choices>
Holds the NPC in stasis until specified condition. See also 'Wake Radius' and 'Wake Squad'.
  • 0: None
  • 1: Waiting for threat
  • 2: Waiting for PVS
  • 3: Waiting for input, ignore PVS
  • 4: Auto PVS
  • 5: Auto PVS after PVS
Wake Radius <float>
Auto-wake if player within this distance
Wake Squad <boolean>
Wake all of the NPCs squadmates if the NPC is woken
Enemy Filter <targetname>
Filter entity to test targets against
Ignore unseen enemies <boolean>
Prefer visible enemies, regardless of distance or relationship priority
Physics Impact Damage Scale <float>
Scales damage energy when this character is hit by a physics object. With a value of 0 the NPC will take no damage from physics.


Damage Filter <targetname>
Name of the filter_damage_type entity that controls which entities can damage us.


Response Contexts <string>
Pre-defined response system contexts for this entity. Format is key:value,key:value,...


Disable shadows <boolean>
Prevent the entity from creating cheap render-to-texture shadows. Does not affect shadow mapping.
Disable ShadowDepth <boolean> (New with Portal 2)
Used to disable rendering into shadow depth (for projected textures) for this entity.
Projected Texture Cache <choices> (New with Portal 2)
Used to hint projected texture system whether it is sufficient to cache shadow volume of this entity or to force render it every frame instead.
  • 0 : Default
  • 1 : No cache - render every frame
  • 2 : Cache it - render only once
Disable flashlight <boolean> (New with Portal 2)
Used to disable projected texture lighting and shadows on this entity.


Render Mode <choices>
Set a non-standard rendering mode on this entity. See Render Modes for details.
FX Amount (0 - 255) <int>
Intensity of the selected render mode.
FX Color (R G B) <color255>
Color used by the selected render mode (if applicable).
Disable Receiving Shadows <bool>
Prevents the entity from receiving shadows.


Render FX <choices>
Several GoldSrc-era visibility modes which change the way the entity is rendered, typically by fading it in and out.


Pitch Yaw Roll (Y Z X) <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.


Name <string>
The targetname that other entities refer to this entity by.
Entity Scripts <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 <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.
Start Buried <boolean>
To do: add description
Sight Distance <choices>
To do: add description
Literal Value Description
0 Ignore distant targets not in a vehicle (default).
1 Equal visibility for all targets.


  • 1 : Wait Till Seen
  • 2 : Gag (No IDLE sounds until angry)
  • 4 : Fall to ground (unchecked means *teleport* to ground)
  • 8 : Drop Healthkit
  • 16 : Efficient - Don't acquire enemies or avoid obstacles
  • 128 : Wait For Script
  • 256 : Long Visibility/Shoot
  • 512 : Fade Corpse
  • 1024 : Think outside PVS
  • 2048 : Template NPC: This entity is a template for the npc_template_maker. It will not spawn automatically and cannot be used with point_template.
  • 4096 : Do Alternate collision for this NPC (player avoidance)
    This flag is disabled in episodic for player companions because the start scripting input does this.
  • 8192 : Don't drop weapons
  • 16384 : Ignore player push : Dont give way to player
  • 65536 : Friendly
  • 131072 : Use prop_physics collision rules



SetRelationship <string|targetname or classname> <string|disposition> <int|rank>
Changes whether this NPC likes or dislikes certain others. Used like the ai_relationship entity, with this NPC as the subject.
Values for disposition are:
  • D_HT: Hate
  • D_FR: Fear
  • D_LI: Like
  • D_NU: Neutral
SetHealth <int>
Set the NPC's health.
AddHealth <int> (New with Source 2007)
RemoveHealth <int> (New with Source 2007)
Add to or remove from the NPC's health.
SetBodyGroup  <integer>
HACK: Sets this NPC's body group (from 0 - n).
physdamagescale  <float>
Scales the damage taken when this character is hit by a physics object. 0 means this feature is disabled for backwards compatibility.
Burst into flames.
IgniteLifetime  <float>
Ignite for the given number of seconds.
IgniteNumHitboxFires  <integer>
Ignite with the given number of hitbox fires.
IgniteHitboxFireScale  <float>
Ignite with the given hitbox fire scale.
Smash into pieces. If this is not possible, disappear.
BecomeRagdoll (New with Source 2007)
Remove itself and instantly become a ragdoll with zero force (just go limp). OnDeath, etc. Outputs will NOT be fired.
Enter/exit scripting state, where NPCs ignore a variety of stimulus that would make them break out of their scripts. They ignore danger sounds, ignore +USE, don't idle speak or respond to other NPC's idle speech, and so on.
Assault  <targetname>
Start an assault at the given rally point.
SetSquad  <string>
Change the name of this NPC's squad. Leaving the parameter blank will remove the NPC from any existing squad.
Wakes up the NPC if it is sleeping.
ForgetEntity  <targetname>
Clears out the NPC's knowledge of a named entity.
Gagged NPCs won't speak (or moan, caw, etc.) unless made to be a choreographed scene.
IgnoreDangerSounds  <float>
Ignore danger sounds for the specified number of seconds.
Force the NPC to holster or unholster their weapon. Ignored if the NPC is scripting or if the NPC doesn't use weapons.
As HolsterWeapon, except the weapon is destroyed once it has been concealed.
ForceInteractionWithNPC <string>  <string>
Force the NPC to use a dynamic interaction with another NPC. Syntax is <targetname> <dynamic interaction>.
Update (or create) this NPC's memory of of the given entity.


Alpha  <integer>
Set the sprite's alpha (0 - 255).
Color  <color255>
Set the sprite's color (R G B).


SetDamageFilter  <string>
Sets the entity to use as damage filter. Pass in an empty string ("") to clear the damage filter.


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.
Removes all contexts from this entity's list.


Turn shadow off.
Turn shadow on.
DisableReceivingFlashlight  (New with Portal 2)
This object will not receive light or shadows from projected textures.
EnableReceivingFlashlight  (New with Portal 2)
This object may receive light or shadows from projected textures.


Removes this entity from the world.
Removes this entity and all its children from the world.
AddOutput  <string>
Evaluates a keyvalue/output on this entity. It can be potentially very dangerous, use with care.
Format: <key> <value>
Format: <output name> <targetname>:<inputname>:<parameter>:<delay>:<max times to fire, -1 means infinite>
FireUser1 to FireUser4
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.
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.
In <Left 4 Dead 2>, 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)
Execute a VScript function in the scope of the receiving entity.
This input is missing from some games FGD files.


Shutdown this target.
Restore this rollermine to normal functionality.
Make this rollermine completely inert. Does not run AI and NPCs will ignore it.



Fired when this NPC takes damage (activator is the damage inflictor)
Fired when this NPC is killed (activator is the killer)
Fired when this NPC reaches half of its maximum health
Fired when this NPC hears a sound (other than combat or the player)
Fired when this NPC hears the player
Fired when this NPC hears combat sounds
OnFoundEnemy  <targetname>
Fired when this NPC establishes line of sight to its enemy
Fired when this NPC loses line of sight to its enemy
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
OnFoundPlayer  <targetname>
Fired when this NPC establishes line of sight to its enemy, and that enemy is a player
Fired when this NPC loses line of sight to its enemy, and that enemy is a player
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
Fired when this NPC is hurt by a player (activator is the attacker or vehicle driver (if friendly fire))
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))
Fired when this NPC has refused to join the player's squad
Fired when this NPC enters a sleep state
Fired when this NPC comes out of a sleep state
Fired when the NPC starts a forced interaction.
Fired when the NPC aborts a forced interaction for some reason (target NPC died, couldn't be pathed to, etc)
"NPCs in actbusies can no longer perform dynamic interactions." To do: What does this mean?
OnUser1 to OnUser4
These Outputs each fire in response to the firing of the like-numbered FireUser1 to FireUser4 Input; see User Inputs and Outputs.

(New with Left 4 Dead)

This Output fires when the entity is killed and removed from the game.
Fired when Alyx begins to interact with this entity.
Fired when Alyx has finished interacting with this entity.
Picked up with physgun (activator is the player).
Released by physgun (activator is the player).