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An env_portal_path_track beam (top) versus the final effects (bottom)
[Portal] [Portal 2] env_portal_path_track is a point entity available in the Portal series. It is an unfinished variant of path_track which produces a visible light rail along the path. It was presumably meant for the Unstationary Scaffold, but the final game uses regular path_tracks and env_beams for this.
Bug: A func_tracktrain cannot start at an env_portal_path_track. It can still follow them as long as the starting node is a regular path_track.
Bug: Copying an env_portal_path_track in Hammer will not automatically rename it or link the previous node.


Scale Track FX (Track_beam_scale) <float>
The amount to scale the track FX size
Bug: Appears non-functional
Scale Endpoint FX (End_point_scale) <float>
The amount to scale the endpoint FX size.
Bug: Appears non-functional
Fade Out Endpoint (End_point_fadeout) <float>
Amount of time to fade out the endpoint FX
Bug: Appears non-functional
Fade In Endpoint (End_point_fadein) <float>
Amount of time to fade in the endpoint FX
Bug: Appears non-functional
Next Stop Target (target) <targetname>
The next node in the path. This can be another env_portal_path_track, or a regular path_track
Branch Path (altpath) <targetname>
An alternative path_track to be the next node in the path. Useful for making branching paths. Use the ToggleAlternatePath / EnableAlternatePath inputs to make the alternative path active.
New Train Speed (speed) <float>
When the train reaches this path_track, it will set its speed to this speed. This speed must be a positive value that is less than the train's max speed. A value of 0 will cause no change in the train's speed.
Path radius (radius) <float>
Used by NPCs who follow track paths (attack chopper/gunship). This tells them the maximum distance they're allowed to be from the path at this node.
Orientation Type (orientationtype) <choices>
The way that the path follower faces as it moves through this path track.
  • 0 : No change
  • 1 : Face direction of motion
  • 2 : Face this path_track's angles


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> (in all games since <Left 4 Dead 2>) !FGD
If Yes, disables this entity on the Xbox 360 version of Source.
Entity Scripts (vscripts) <scriptlist> (in all games since <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> (in all games since <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> (in all games since <Left 4 Dead 2>) !FGD
Set to Yes to lag compensate this entity. Should be used very sparingly!


  • 1 : Disabled
  • 2 : Fire once
  • 4 : Branch Reverse
  • 8 : Disable train
  • 16 : Teleport to THIS path track


Cause the track to toggle to/from its alternate path.
Enable the alternate path of the track.
Disable the alternate path of the track.
Cause the track to toggle on/off/
Enable the track.
Disable the track.
Enable the track beam FX
Disable the track beam FX
Enable the endpoint FX
Bug: Appears non-functional
Disable the endpoint FX
Bug: Appears non-functional


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 Kill.
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.
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 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.
DispatchEffect <string> (removed in <Left 4 Dead>) !FGD
Dispatches a special effect from the entity's origin. Removed and replaced entirely by the particle system since <Left 4 Dead>.
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> (in all games since <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> (in all games since <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 <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> (in all games since <Left 4 Dead 2>) !FGD
Execute a VScript function in the scope of the receiving entity.
SetLocalOrigin <coordinates> (in all games since <Alien Swarm>) !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> (in all games since <Alien Swarm>) !FGD
Set this entity's angles.


Fired when any entity following this path passes this path_track node.


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.