This guide is intended for mod developers. To play with the turrets check out the Gnome Guardians Mutation:
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=507377833

Note: You will need the GCFScape[nemesis.thewavelength.net] tool to unpack the content.

To download the Turret System Add-on, subscrive to it on the Workshop.
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=510573647

After subscribing to the add-on and lauching Left 4 Dead 2, find the add-on in the Steam\SteamApps\common\left 4 dead 2\left4dead2\addons\workshop\ directory.


Open the add-on .vpk file using GCFScape.

Copy the directories materials, models and scripts into the Steam\SteamApps\common\left 4 dead 2\left4dead2\ directory. The content of these directories will also have to be added to any add-ons realesed with the turret system, except from a few files: turretsystem_demo_spawn_entitygroups.nut and the models and materials for the turret crates.

If you want to add turrets directly to a map, also extract the files from mapsrc/instance/ to the directory or a subdirectory of where you have your map (Steam\SteamApps\common\left 4 dead 2\sdk_content\mapsrc\ by default).

Instances are used to include separate .vmf files into maps. The turret instance files contain the entities needed for each turret.

To place a turret, add a func_instance entity to the map where you want the turret to spawn. Open up its properties, and use the VMF Filename to find the instance file.

If all the assets were unpacled correctly, an orange tinted turret should appear on the entity.



For the scripts to be able to address individual turrets, the entities inside each instance need unique names with common pre- or postfixes. With the default instance settings, they will be generated correctly. If you want to give the turrets manual names, make sure that the Fix Up name is unique for every turret.


For more complex scenarios, the turrets can also be spawned using point_template entities. To do that, the turret parts can be copied over to the main map, and each turret part be added to the point_template. The naming convension still applies, but the point_template will automatically handle postfixes.

The turrets are originally designed to be spawned for mutations using VScript based Entity Groups. Entity Groups are most commonly spawned by placing an info_item_position entiy as a marker, either by directly placing it in a custom map with Hammer, or by using the Entity Placement Tool to place it in any map, and then using one of the many spawning methods.


Please see this Dev Wiki article on how to use the Entity Placement Tool:
https://developer.valvesoftware.com/wiki/L4D2_EMS/Appendix:_Spawning

To get a preview of the turret, set the template Entity group to the file name of the turret group. The groups can be found under Steam\SteamApps\common\left 4 dead 2\left4dead2\scripts\vscripts\entitygroups\.

The Target Name needs to be set correctly for the spawning systen to find the positions.





To spawn the placed turrets in a map on load, the turret group names are placed in the MapSpawns table in the Map Script.