path_track

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Path track.png


path_track is a point entity available in all Source games. It is used to build paths for other entities to follow. Each path_track is a node on the path, each holding the name of the next path_track in the path.

Automated track creation

Cloning (Shift-drag) this entity will activate a feature used to automatically and quickly create a track. This feature will alter both the Name keyvalue, and the Next Stop Target keyvalue, so that a track is created between the source and the clone. More specifically, Hammer will add a counter after the Name keyvalue of the clone, or increment this counter if it already exists, creating a unique name in a series. If a name is completely omitted, it will simply name the clone "path". If a Next Stop Target keyvalue has been specified, it will also alter this keyvalue of the source, to the name of the clone, resulting in a track being drawn between them.

Reversing over a path_track

Bug: Normally, when given a StartBackward or Reverse input, a func_tracktrain will begin moving in reverse direction at its normal speed. However, due to coding glitches, if some of the path_tracks involved in the course have their "New Train Speed" property value set to 0, the train may stop moving, or may move in the wrong direction. This issue can be solved by setting the "New Train Speed" property in the involved tracktrains to a number other than zero.

Parenting

A set of tracks can be parented. However, all tracks and the train running on them must be parented to the same object for movement to behave correctly. Failure to do so will lead to an intentional crash.

Keyvalues

Next Stop Target <targetname>
The next path_track in the path.
Branch Path <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.
Bug: If this value is set to anything that isn't a path_track, the game will crash without notice upon loading the level.
New Train Speed <float>
When the train reaches this path_track, it will set its speed to this speed. Speeds higher than the max speed of the train are clamped.
Path 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 <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

Targetname:

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.
Note:Try to avoid expensive operations in this function, as it may cause performance problems.

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.

Angles:

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.

Flags

  • 1 : Disabled
  • 2 : Fire once
  • 4 : Branch Reverse (Alternative path is for going backwards, not forwards)
  • 8 : Disable train
  • 16 : Teleport to THIS path track
  • 32 : TF2 payload uphill zone
  • 64 : TF2 payload downhill zone

Inputs

ToggleAlternatePath
Cause the track to toggle to/from its alternate path.
EnableAlternatePath
Enable the alternate path of the track.
DisableAlternatePath
Disable the alternate path of the track.
TogglePath
Cause the track to toggle on/off
EnablePath
Enable the track.
DisablePath
Disable the track.

Targetname:

Kill
Removes this entity and any entities parented to it from the world.
KillHierarchy
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.
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.
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> (New with Left 4 Dead 2) !FGD
Execute a VScript function in the scope of the receiving entity.
SetLocalOrigin  <coordinates> (New with 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> (New with Alien Swarm) !FGD
Set this entity's angles.

Parentname:

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.
ClearParent
Removes this entity from the the movement hierarchy, leaving it free to move independently.

Outputs

OnPass
Fired when any entity following this path passes this path_track node.
OnTeleport
Fired when any entity following this path teleports directly to this path_track node.

Targetname:

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.
OnKilled  (Only in the Left 4 Dead series)
This Output fires when the entity is killed and removed from the game.

See also