Behavior Graph

Nodes inside Nodes inside Nodes

A Behavior is defined by a Behavior component, which is linked to a Behavior Graph object. In this section, we'll focus on the Behavior Graph, which tells the targeted game object what to do based on a set of inputs.

The Behavior Graph asset

To create a Behavior Graph asset right click on your Project Panel and select Create → Game Creator → Behavior → Behavior Tree. You can name it however you want as well as place it anywhere.

We recommend creating a Behaviors/ folder at the root of your project and organize all your trees there.

The Behavior Graph Window

To bring up the Behavior Graph window simply go to the top toolbar and select Window → Behavior. Alternatively, when you double click on a Behavior Graph asset it will automatically open the window.

(Behavior Graph window with a Task node selected)

The Behavior Window is split in different sections:

Top Toolbar

This section is one of the most important sections of the entire module.

The Blackboard button toggles the Blackboard.

The Slider next to it is the amount of zoom. You can either drag it or use the mouse wheel to zoom in/out of the Canvas.

The Sort button re-arranges your nodes based on their size and dependencies. It is highly advisable to click it every once in a while.

The Create button opens a dropdown of options which place nodes on the node Canvas. See the Nodes section for a full list of all available nodes.

The Maximize button maximizes the window for maximum comfort.

The Canvas

Here is where the magic happens. The Canvas entry point is a special node called Root or Entry. The rest of the nodes are children of the root and there can't be any cycles (hence the name tree).

Click here for more information about Nodes and how they are executed.

Breadcrumbs

A Behavior Graph can use other Behavior Graphs as nodes. When you enter on a Behavior Graph node you can quickly go back to any of its parent's Behavior graph.

It's highly recommended to group your behaviors in sub-behavior graphs. Doing so will allow you to reuse behaviors such as a wandering behavior for both an Archer and a Guard, but still have complete different behaviors when spotting the player and switching to an attack behavior.