Behavior Trees

Every node graph in Eldiron (except area nodes which are more simple) utilizes behavior trees to break up the overall behavior into smaller, easily understandable chunks.

A behavior tree is just a node with several terminals at the bottom which get executed from left to right. You typically rename the behavior tree to indicate what behavior the tree is executing, for example Go Raiding, or Talk and Combat.

Every behavior tree node has an Execute property which indicates when the tree is executed:

  • Always. The behavior tree is always executed if the graph is not locked.
  • On Startup. The behavior tree is only executed once when the graph is created.
  • On Target. The behavior tree is executed when somebody is targetting (i.e. interacting) with the character. You can than decide to lock a certain tree which handles the given situation (combat, having a talk or selling something) and unlock the tree when the situation is handled and normal behavior is resumed.

Behavior trees perform the AI for non-player-characters (NPCs) and connect input commands from the Player character to the right player action (see the characters section).

All behavior trees in a graph are listed as tabs at the top of the graph. Select the given behavior to edit it.


When you debug a game, the graph will visualize which node connections are being executed by coloring executed connections in orange.