Interactables

Interactables are objects in the game world that can be interacted with, and trigger a specific effect when this is done. Effects can be spells cast on the interactable target, or other specified targets, or changes made to the game world. Technically, virtually anything can be done.

Constructing an Interactable
Interactables require a scene with a CharacterBody3D root node, and an attached script that inherits from BaseInteractable. Mandatory child nodes are a Label3D node named "interact_prompt", an Area3D node named "range" that scans collision layer 2, and which has a CollisionShape3D child node named "range_shape" that uses a SphereShape3D as shape, and finally a MultiplayerSynchronizer node named "mpsynchronizer".

The attached script needs to set the multiplayer authority to 1 (the server) in the _enter_tree function, and needs to call create_prompt_text and initialize_base_interactable from the BaseInteractable class. create_prompt_text needs to be called locally for all players, i.e. for all peers that are NOT multiplayer authority. The initialization of the base interactable needs to be called on the server, i.e. for the multiplayer authority.

The script further requires a trigger function, which uses the root node of the interacting player scene as an argument. The BaseInteractable class contains a trigger function, which will warn the server via a printed message if it is not overriden in the script of a specific interactable.

If a spell is to be triggered by interacting, the spell must be triggered directly, and not via the spell_container entrypoint. This is to allow for the easy reuse of the spell_container scene, but to still be able to pass the interacting player as an argument as the target of the triggered spell.

BaseInteractable
The BaseInteractable class is the class from which interactables inherit. It contains a stats_current variable, which is required to calculate spell effects, contains the maximum range at which interactions can occur, and contains the array of spells the interactable has available.

The BaseInteractable class further contains a number of functions:

initialize_base_interactable takes the unit ID of the interactable to read the stats from the data/db_stats_interactable.json file, sets up the spell container with all required spells, calls the connect_signals function described below, and sets the maximum interaction range.

connect_signals connects the body_entered and body_exited signals of the "range" child node to the add_interactable and remove_interactable functions described below. The shape and size of the body of the "range" node is determined by its "range_shape" child node, and should be set to a SphereShape3D.

add_interactable adds an interactable to the array of interactables of a player when they enter the body of the interactable.

remove_interactable removes an interactable from the array of interactables of a player when they exit the body of the interactable.

Note: A player can only interact with the nearest interactable within their interactables array. The nearest interactable is searched for every frame by the get_nearest_interactable function in the player script. This function also uses rpc to show or hide interact prompts as necessary for the corresponding player. The interact prompt is only shown above the current nearest interactable, to clearly indicate which interactable is triggered if the interaction hotkey is used.

create_prompt_text creates the text that is shown in the interact_prompt label. The prompt is "Interact [%s]", with %s being the hotkey for interactions, where the " (Physical)" suffix is trimmed, if it is part of the hotkey.

trigger is a function that provides a warning in the server standard output if it is not overridden by a trigger function in the interactable script that inherits from BaseInteractable.

Adding a New Interactable
When adding a new interactable, it should be placed in the "interactable" subdirectory of the "scenes" directory, and the script for it should be placed in the "interactable" subdirectory of the "scripts" directory. A basic template for interactables can be found in the testing subdirectory of these directories, as interact_absorb, interact_damage, and interact_heal.