env_headcrabcanister

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January 2024

env_headcrabcanister is an e0 available in Half-Life 2 series. The canister is a mortar shell containing a payload of headcrabs. The mortar shell inflicts damage within a radius of where it lands and releases headcrabs after impact. Inputs and keyvalues offer control over impact damage and when the headcrabs are released, among other options.

For an example of their use, see the shantytown in d1_canals_05.

Note:This entity is also in the code for . Its functionality is not guaranteed.

In code, it is represented by theCEnvHeadcrabCanisterclass, defined in theenv_headcrabcanister.cppfile.

ConVars/Commands

Cvar/Command	Parameters or default value	Descriptor	Effect
sk_env_headcrabcanister_shake_amplitude	50	Arbitrary decimal (float)	Crash effect's shake amplitude. Though the default is 50, the shake amplitude can only go up to 16.
sk_env_headcrabcanister_shake_radius	1024	Hammer units	Radius the player must be within for the screen shake effect to occur. Shake amplitude is gradually decreased the farther away from the explosion the player is.
sk_env_headcrabcanister_shake_radius_vehicle	2500	Hammer units	As above, but when in a vehicle.

Flags

• 1: No Impact Sound
• 2: No Launch Sound
• 4096: Start Impacted
• 8192: Land at initial position
• 16384: Wait for input to open
• 32768: Wait for input to spawn headcrabs
• 65536: No smoke
• 131072: No shake
• 262144: Remove on impact
• 524288: No impact effects

Keyvalues

Which headcrab to Spawn? (HeadcrabType) ([todo internal name (i)]) <choices>

Select which headcrab will jump out the canister.

• 0: Normal headcrabs
• 1: Fast Headcrabs
• 2: Poison Headcrabs

Headcrab count (HeadcrabCount) ([todo internal name (i)]) <integer>

Number of headcrabs to spawn on impact.

Min Refire time (MinSkyboxRefireTime) ([todo internal name (i)]) <float>

Min number of seconds before the canister is refired. This will only work for canisters placed in the skybox.

Max Refire time (MaxSkyboxRefireTime) ([todo internal name (i)]) <float>

Max number of seconds before the canister is refired. This will only work for canisters placed in the skybox.

Canister count (SkyboxCannisterCount) ([todo internal name (i)]) <integer>

Number of canisters to produce and fire across the skybox. The target should be positioned inside the skybox. 0 means fire continuously, forever.

Impact damage (Damage) ([todo internal name (i)]) <float>

Max damage the canister applies on impact.

Impact damage Radius (DamageRadius) ([todo internal name (i)]) <float>

Max radius of the impact damage for the canister.

Smoke duration (SmokeLifetime) ([todo internal name (i)]) <float>

Duration that the canister smokes. -1 means always smoke.

Launch Position Name (LaunchPositionName) ([todo internal name (i)]) <targetname>

If the canister should launch to its origin from another point within the world, this should specify an info_target at the launch origin.

Flight Speed (FlightSpeed) ([todo internal name (i)]) <float>

Speed to fly through the air.

Flight Time (FlightTime) ([todo internal name (i)]) <float>

Time to fly through the air in seconds.

Starting Height (StartingHeight) ([todo internal name (i)]) <float>

Relative height from the landing position at which the canister should be launched. Positive values mean launch it above the impact point, negative values mean launch it below.

Note:Content moved to Rendering and studio model related KIO/Keyvalues for continuation of page history

Inputs

FireCanister

Fires the canister.

OpenCanister

Opens the canister (must be called after the OnImpacted output is fired).

SpawnHeadcrabs

Spawns headcrabs (must be called after the OnImpacted output is fired and after OpenCanister is triggered, if the Wait for Input to open' flag is checked).)

StopSmoke

Causes the smoke effect to stop.

Note:Content moved to Rendering and studio model related KIO/Inputs for continuation of page history

Outputs

OnLaunched <targetnameRedirectInput/string>

Fired when the canister is launched. This output automatically puts the targetname of the canister into the parameter box for inputs, if the mapper does not override the parameter with something else.

OnImpacted

Fires when canister hits the ground.

OnOpened

Fires when canister has finished opening.

Note:Content moved to Rendering and studio model related KIO/Outputs for continuation of page history