Create a custom node

If you can't find the required node in the pre-defined node list of Unity Behavior, you have the option to create custom nodes. You can create custom Action, Modifier, and Sequencing nodes.

This section outlines the process for creating a custom Action node. You can apply these instructions identically to create custom Modifier and Sequencing nodes.

To create a custom node, perform the following steps:

  1. Right-click an empty area of the Unity Behavior graph editor and select Create new.

    You can create three different types of nodes: Action, Modifier, and Sequencing.

    Custom node

  2. To create a custom Action node, select Action.

    The New Action window appears.

  3. Enter a name for the action that describes the agent's behavior in the Name field. For example, Agent runs away.

  4. Select a category from the Category list if you want to sort the new node in a particular subgroup in the menu or leave it with the default Action value so that it's available at the root of the Action node list.

    For example, you can place the new action node, Agent runs awayin the Action/Move category.

  5. Select Next.

    Unity Behavior adds the new custom node to the behavior graph.

    New action node

  6. Enter a description for your action in natural language.

    This information will determine how the node appears on the graph and what link fields the node will have. For example, Agent runs away from the enemy and hides behind a tree for 2 seconds.

    Unity Behavior lists all the elements specified in the action on the window along with a list of data types.

    Describe action

  7. Select the appropriate variable from the list for each element.

    Note

    When describing the action, if you use a word that's the same as one of the Blackboard variables, it's automatically assigned the correct data type. For example, if the word Target with the GameObject data type is already defined on the Blackboard and you use it when describing the action, Unity Behavior will automatically assign the GameObject data type to the word Target.

  8. Select Create to manually create the new custom node type or select Use Generative AI to create the base of the node's logic. For information on using the Generative AI feature, refer to Create a behavior graph with Unity Behavior's generative AI.

    Unity Behavior generates a new C# script that defines the logic of the node. It has the story (as defined previously) as an attribute and the link fields as Blackboard variables. Additionally, it contains some empty overrides for the three possible entry points for a node's logic: OnStart, OnUpdate, and OnEnd.

    The new action type appears in the context menu when you select Add > Action > [sub_category] > [new_node].

    New node

  9. Select the new node to use it in the behavior graph.

    Behavior graph

Additional resources