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An env_portal_path_track beam (top) versus the final effects (bottom)

env_portal_path_track is a point entity available in the Portal (series) Portal games. 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.

Icon-Bug.pngBug: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.
Icon-Bug.pngBug: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
Icon-Bug.pngBug:Appears non-functional
Scale Endpoint FX (End_point_scale) <float>
The amount to scale the endpoint FX size.
Icon-Bug.pngBug:Appears non-functional
Fade Out Endpoint (End_point_fadeout) <float>
Amount of time to fade out the endpoint FX
Icon-Bug.pngBug:Appears non-functional
Fade In Endpoint (End_point_fadein) <float>
Amount of time to fade in the endpoint FX
Icon-Bug.pngBug: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

Name (targetname) <string>
The name that other entities use to refer to this entity.
Parent (parentname) <targetname>
Maintain the same initial offset to this entity. An attachment point can also be used if separated by a comma at the end. (parentname [targetname],[attachment])
Tip.pngTip:Entities transition to the next map with their parents
Tip.pngTip:phys_constraint can be used as a workaround if parenting fails.
Origin (X Y Z) (origin) <coordinates>
The position of this entity's center in the world. Rotating entities typically rotate around their origin.
Note.pngNote:Hammer does not move the entities accordingly only in the editor.
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.pngNote:This works on brush entities, although Hammer doesn't show the new angles.
Classname (classname) <string> !FGD
Determines the characteristics of the entity before it spawns.
Tip.pngTip:Changing this on runtime still has use, like making matching an entry in S_PreserveEnts will persist the entity on new rounds!
Flags (spawnflags) <integer> !FGD
Toggles exclusive features of an entity, its specific number is determined by the combination of flags added.
Effects (effects) <integer> !FGD
Combination of effect flags to use.
Entity Scripts (vscripts) <scriptlist> (in all games since Left 4 Dead 2) (also in Team Fortress 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. Scripts executed on the worldspawn entity will be placed in root scope.
Think function (thinkfunction) <string> (in all games since Left 4 Dead 2) (also in Team Fortress 2)
Name of the function within this entity's script that'll be called automatically every 100 milliseconds, or a user-defined interval if the function returns a number. 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
Icon-Bug.pngBug:Appears non-functional
Disable the endpoint FX
Icon-Bug.pngBug:Appears non-functional

AddContext <string>
Adds to the entity's list of response contexts. See Context.
AddOutput <string>
Assigns a new keyvalue/output on this entity. For keyvalues, some rely on extra necessary code to be ran and won't work if its simply just changed through this input. There is a strict format that must be followed:
// Format of changing KeyValues: "AddOutput [key] [value]"
//// Raw text:
"OnUser1" "!self,AddOutput,targetname new_name"

// Format of adding an Output: "AddOutput {targetname}:{inputname}:{parameter}:{delay}:{max times to fire, -1 means infinite}"
//// Raw text:
"OnUser1" "!self,AddOutput,OnUser1:SetParent:!activator:0.0:-1"
// Arguments can be left blank, but the empty blank should still be contained.
//// Raw text:
"OnUser1" "!self,AddOutput,OnUser1:ClearParent::0.0:-1"
Removes all contexts from this entity's list.
Removes this entity from the the movement hierarchy, leaving it free to move independently.
FireUser1 to FireUser4
Fires the respectiveOnUseroutputs; see User Inputs and Outputs.
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 thanKillinput.
RemoveContext <string>
Remove a context from this entity's list. The name should match the key of an existing context.
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.
Use  !FGD
Same as a player invoking +use; no effect in most cases.
DispatchResponse <string> !FGD
Dispatches a response to the entity. See Response and Concept.
DispatchEffect <string> (removed since Left 4 Dead) !FGD
Dispatches a special effect from the entity's origin; See also List of Client Effects. Replaced by the particle system since Left 4 Dead.
RunScriptFile <script> (in all games since Left 4 Dead 2) (also in Team Fortress 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) (also in Team Fortress 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.
Icon-Bug.pngBug:In Hammer, using string arguments will corrupt the VMF file's structure, making the file unviewable for the next Hammer session.
Note.pngFix:Remove the string argument manually with a text editor.
Note.pngNote:Team Fortress 2 Backtick characters ` are replaced with quotation marks at runtime, allowing quotation marks to be used when normally not possible.
CallScriptFunction <string> (in all games since Left 4 Dead 2) (also in Team Fortress 2) !FGD
Calls a VScript function defined in the scope of the receiving entity.
TerminateScriptScope  (only in Team Fortress 2) !FGD
Destroys the script scope of the receving 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.