Variables

A tree declares named, typed variables in the AI Editor's Variables page. Nodes read and write them while the tree runs, and your code can set them through the AI component (see Runtime Integration).

Types

Variable definitions live in VariableType. The main variable types are:

Type	VariableType	Use
string	String	text
int	Int	integer
float	Float	decimal number
bool	Bool	state
Vector2	Vector2	2D vector
Vector3	Vector3	3D vector
Vector4 / Color	Vector4	4D vector or color
UnityEngine.Object	UnityObject	Unity object reference
object	Generic	arbitrary object

Invalid and Node are hidden/internal types and are usually not selected manually in a normal variable table.

Variables with the same name are not allowed in the same tree, even if they have different types.

Scope

Initial definitions come from the asset; each runtime BehaviourTree builds its own variable table when it initializes.

Scope	Shared by
Local (default)	Nothing; each runtime tree has its own value.
Static	Every runtime instance of the same tree asset.
Global	Every tree. Declared in Project Settings > Aethiumian AI > AI Settings.

A local Float variable can also use a Timer source; see Timers and admission nodes for Timer sources, Cooldown, Throttle, Countdown services, and historical name migration.

Variables in node fields

Nodes refer to variables through these field forms:

Declaration	Meaning
float	fixed constant
VariableField<float>	float variable or constant
VariableReference<float>	float variable reference
VariableField	any variable or constant; actual valid types depend on node logic
VariableReference	any variable reference; actual valid types depend on node logic

Even when a non-generic field allows any variable, the node itself may only support specific types. For example, a boolean arithmetic node cannot use a string as a boolean argument.