Logic script

Source Engine

Source 2

Class hierarchy
CLogicScript ↳CPointEntity ↳CBaseEntity
logicentities.cpp

logic_script is a logical entity available in all Source games since Left 4 Dead 2. It is also available in the Team Fortress 2 branch and Mapbase.

This entity functions as a container for VScripts. In Left 4 Dead 2, for example, it is used extensively for the logic in "carnival games" found in the Dark Carnival campaign, such as Peanut Gallery, Strongman Contest, Whack-a-Stach, etc.

Note:This entity counts as an edict, not a logical entity as one would expect.

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

EntityGroup[0] (Group00) to EntityGroup[15] (Group15) <targetname>

Targetnames of entities to make them accessible in Squirrel code. All specified entity names will be searched for upon this entity spawning and their script handles are added to this logic_script's script scope:

• EntityGroup: an array where EntityGroup[0] is the handle of an entity with the name specified in the EntityGroup[0] keyvalue etc. If multiple entities exist with that name, the first handle found is used. The array length is the highest non-empty EntityGroup index that is not empty plus one, so in Squirrel code, be sure to not hardcode indices if the length is uncertain. If the keyvalue EntityGroup[i] is the empty string (for i < EntityGroup.len()), then EntityGroup[i] is null.
• MyEntityGroup (not in ): a table which contains the handles with keys being the names, for example if the EntityGroup[2] keyvalue is set to sound.start, then MyEntityGroup["sound.start"] == EntityGroup[2].
• MyEntityGroupArray (not in ): an array which is the same as EntityGroup.

VScript run internally to achieve this

The following VScript is run in logic_script scope when it spawns. __AppendToScriptGroup is then called with each name specified by Group00-Group15 keyvalues. EntityGroup <- []; MyEntityGroup <- {}; MyEntityGroupArray <- EntityGroup; function __AppendToScriptGroup( name ) { if ( name.len() == 0 ) { EntityGroup.append( null ); } else { local ent = Entities.FindByName( null, name ); EntityGroup.append( ent ); if ( ent != null ) { ent.ValidateScriptScope(); MyEntityGroup[name] <- ent; ent.GetScriptScope().EntityGroup <- EntityGroup; } } }

Note:For other VScript keyvalues notable for this entity like vscripts, thinkfunction and inputs like RunScriptCode, CallScriptFunction see Generic Keyvalues, Inputs and Outputs

See also

• L4D2 VScripts
• Left 4 Dead 2 Tool Updates

External links

• It's the VScripting documentation FAQ! (Steam Forums)
• Scripting for Left 4 Dead 2 (Leeland.net) - Example uses of logic_script