physics_cannister

Class hierarchy
CPhysicsCannister ↳CBaseCombatCharacter ↳CBaseFlex ↳CBaseAnimatingOverlay ↳CBaseAnimating ↳CBaseEntity
physics_cannister.cpp

physics_cannister is a model entity available in all Source games. It is a physically simulated gas canister (with a misspelled entity name) that can have its cap shot off, at which point gas will start escaping, causing the canister to fly around. If it takes enough damage, it will explode.

A fire extinguisher turned into a physics_cannister by adding a nozzle attachment to the top. Thrust will be applied along the blue line.

A gif of a physics cannister (in an official Half-Life 2 map) having its cap shot off and flying into a wall, then it being shot again causing it to explode.

Bug:This entity exists in , but it remains unused and no fitting prop for it exists. It works if a model is added; however, once the thrusting is finished, it interacts glitchily when stood on. It pushes you off the canister prop in unpredictable ways, and the survivor bots keep melee bashing into it when standing nearby.

Bug:This entity also exists in , also unused and with the default prop missing.

Confirm:is it just as glitchy there as in L4D2?

Note:The model should have a nozzle attachment point, which is where gas will escape and thrust will be produced from.
The thrust will be simulated along the Z axis, visualized as the blue line of the attachment in HLMV.

Usable models in Half-Life 2:

• models/props_c17/canister01a.mdl
• models/props_c17/canister02a.mdl
• models/props_c17/canister_propane01a.mdl

Entity behavior

By default, physics_cannister spawns with 25 health. If its health is overriden to be at or below 0, it will also reset to 25. The canister will activate and start flying in the following cases:

• If fired at, with damage taken being less than the canister's health;
• If taking explosive damage less than the canister's health;
• If taking melee or crushing damage, but only 50% of the time;
• If being picked up and launched by the Gravity Gun (but not when punted or put down);
• By being inside the Barrel Volume of a func_tankphyscannister when it fires;
• By using the Activate input on the canister.

The canister will explode in the following cases:

• If taking damage that exceeds its health;
• If already active (flying) and taking any bullet/buckshot, explosive, or burn damage;
• If hitting something at >1000 speed.

It should be noted that the canister remains volatile and will explode even after it ceases flight. Rather notoriously, it can also explode, after stopping, when stepped on or pushed against any hard surface.

Canisters used in conjunction with a func_tankphyscannister are programmed to fly in a straight line, otherwise a small offset is applied to the thruster, making the canister fly more chaotically. In addition, canister fired from a func_tankphyscannister fly at 4 times the regular speed, are limited to only 10 seconds of flight, and explode upon touching anything.

Keyvalues

Name (targetname) <string>[ Edit ]

The name that other entities refer to this entity by, via Inputs/Outputs or other keyvalues (e.g. parentname or target).
Also displayed in Hammer's 2D views and Entity Report.

See also:  Generic Keyvalues, Inputs and Outputs available to all entities

Explosion Damage (expdamage) <string>

The amount of damage done by the explosion created when the canister blows up.

Explosion Radius (expradius) <string>

The radius of the explosion to create when the canister blows up.

Health (health) <integer>

The amount of damage the canister takes before exploding.

Thrust (thrust) <string>

When the cap has been blown off, and the escaping gas is thrusting the canister about, this is the amount of thrust generated.

Fuel Seconds (fuel) <string>

The amount of time that gas leaks from the canister before being considered empty.

Smoke Color (R G B) (rendercolor) <color255>

Color of the smoke.

Smoke Alpha (0 - 255) (renderamt) <integer 0–255>

Transparency of the smoke.

Thruster Sound (gassound) <sound>

The sound played when the gas is escaping from the canister.

CBaseCombatCharacter:

Relationship (Relationship) <string> !FGD

<string|targetname or classname> <string|disposition> <int|rank>

Changes whether this entity likes or dislikes certain other things. Used like the ai_relationship entity, with this entity as the subject.

Values for disposition are:

• D_HT: Hate
• D_FR: Fear
• D_LI: Like
• D_NU: Neutral

Physics Impact Damage Scale (physdamagescale) <float>

Multiplier for damage amount when this entity is hit by a physics object. With a value of 0 the entity will take no damage from physics.

Flags

Start Asleep : [1]

Explode : [2]

Confirm:What is this supposed to do? The canister will explode with or without this flag.

Inputs

Activate

Start gas escaping from the canister.

Deactivate

Stop gas escaping from the canister.

Explode

Force the canister to explode.

Wake

Wakes up the canister, if it is sleeping.

CBaseCombatCharacter:

KilledNPC  !FGD

Tells the entity it killed something. Despite the name, this can include a player. This input will be automatically sent by the victim when they die.

physdamagescale <floatRedirectInput/float>

Scales damage energy when this character is hit by a physics object. With a value of 0 the NPC will take no damage from physics.

Outputs

OnActivate

Fired when gas starts to escape from the canister.

OnAwakened

Fired when this entity becomes awake (collision/force is applied).

See also

Func_tankphyscannister - a brush entity that works as a controllable turret that shoots out physics_cannisters.