phys_constraintsystem

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phys_constraintsystem is a point entity available in all Source games. If you have a collection of objects connected by constraints, you may encounter vibration or jiggling. This is because each constraint is solved without regard for any others until you introduce a phys_constraintsystem.

To implement a phys_constraintsystem create one and give it a name, then select the constraints you want to group together and set it as their "Constraint System Manager".

A constraintsystem also allows you to control the number of iterations performed on the constraints, allowing you to allocate more CPU to get the solution tighter. This will help when objects of dissimilar mass are connected, as if a large-mass object is in violation of the constraint it will take more iterations for it to move to a non-violating position/orientation. Ragdolls create a constraint system internally to solve these issues.

Keyvalues

Additional System Iterations <integer>
Adding iterations makes the interactions among constraints in a system tighter. It will not compensate for errors due to collision, but will help in cases where objects of disparate mass are constrained to each other.

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.

Inputs

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.

Outputs

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.