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physics_cannister is a point entity available in all Source games. It is a physically simulated gas cannister that can have its cap shot off, at which point gas will start escaping and cause the cannister to fly around. If it takes enough damage, it will explode.

In code it is represented by class CPhysicsCannister, defined in physics_cannister.cpp.


World model <model path>
The canister model.
Note.png Note:  The model should have a nozzle attachment point, which is where gas will escape and thrust will be produced from.
Explosion Damage <string>
The amount of damage done by the explosion created when the cannister blows up.
Explosion Radius <string>
The radius of the explosion to create when the cannister blows up.
Health <integer>
The amount of damage the cannister takes before exploding.
Thrust <string>
When the cap has been blown off, and the escaping gas is thrusting the cannister about, this is the amount of thrust generated.
Fuel Seconds <string>
The amount of time that gas leaks from the cannister before being considered empty.
Smoke Color (R G B) <color255>
Color of the smoke.
Smoke Alpha (0 - 255) <integer>
Transparency of the smoke.
Thruster Sound <sound>
The sound played when the gas is escaping from the cannister.


Name (targetname) <string>
The targetname that other entities refer to this entity by.
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.
Note.png Note: Try to avoid expensive operations in this function, as it may cause performance problems.


Pitch Yaw Roll (Y Z X) (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.


  • 1 : Start Asleep
  • 2 : Explodes


Activate <string>
Start gas escaping from the cannister.
Deactivate <string>
Stop gas escaping from the cannister.
Explode <string>
Force the cannister to explode.
Wakes up the cannister, if it is sleeping.


Removes this entity from the world.
Removes this entity and its children from the world.
Note.png Note: Entities already remove orphaned children upon being removed, but this input removes all children on the same frame, being marginally faster than Kill.
AddOutput <string>
Adds a keyvalue/output to this entity. It can be potentially very dangerous, use with care.
KV Format: <key> <value>
I/O 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 depending on the entity. Can also be invoked by firing an output that does not specify an input.
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.png 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.png 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 gas starts to escape from the cannister.
Fired when this entity becomes awake (collision/force is applied).


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 <Left 4 Dead><Left 4 Dead 2>)
This output fires when the entity is killed and removed from the game.