AWS Documentation » Amazon Lumberyard » User Guide » Working with Component Entities » Component Reference » Simple State

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Simple State

Component entity system is in preview release and is subject to change.

The Simple State component provides a simple state machine. Each state is represented by a name and zero or more entities. The entities are activated upon entering the state and deactivated upon exiting it. A simple state component may be in NullState, which means no state is active.

Simple State Component Properties

The Simple State component has the following properties:

Initial state

The active state when the simple state component is first activated.

Reset on activate

If selected, simple state returns to the configured initial state when activated, and not the state held before deactivating.

States

The list of states on this simple state component.

State ([0], [1], [2], etc)

Includes a name for the state and a set of entities that are activated when the state is entered and deactivated when the state is exited.

Name

The name of this state. Indicates the state to which to transition on the SetState API.

Entities

List of the entities referenced by this state.

EBus Request Bus Interface

Use the following request functions with the EBus interface to communicate with other components of your game.

For more information about using the Event Bus (EBus) interface, see Working with the Event Bus (EBus) System.

SetState

Sets the active state to the named state.

Parameters

stateName

EBus Notification Bus Interface

Use the following notification functions with the EBus interface to communicate with other components of your game.

For more information about using the Event Bus (EBus) interface, see Working with the Event Bus (EBus) System.

OnStateChanged

Notifies that the state has changed from state oldName to state newName.

Parameters

oldName

newName

The following is an example of script using the Request Bus Interface.

local simplestateexample =
{
    Properties =
    {
        TransitionInterval = 1.0,
        States = {"Houses", "Nope", "Lamps", "Tree", "HouseAndTree", "NoState"},
    }
}
 
function simplestateexample:OnActivate()
      
    self.TransitionCountDown = self.Properties.TransitionInterval
    self.StateIdx = 0
    self.tickBusHandler = TickBus.Connect(self)
    self.stateChangedHandler = SimpleStateComponentNotificationBus.Connect(self, self.entityId)
      
    Debug.Log("SimpleStateComponent activated for entity: " .. tostring(self.entityId.id))
end
 
function simplestateexample:OnDeactivate()
    self.tickBusHandler:Disconnect()
    self.stateChangedHandler:Disconnect()
end
 
function simplestateexample:OnTick(deltaTime, timePoint)
    self.TransitionCountDown = self.TransitionCountDown - deltaTime
    if (self.TransitionCountDown < 0.0) then
        SimpleStateComponentRequestBus.Event.SetState(self.entityId, self.Properties.States[self.StateIdx + 1])
        self.StateIdx = (self.StateIdx + 1) % table.getn(self.Properties.States)
        self.TransitionCountDown = self.Properties.TransitionInterval
    end
end
  
function simplestateexample:OnStateChanged(oldState, newState)
    Debug.Log("Old State: " .. (oldState or "NullState")  .. " => New State: " .. (newState or "NullState"))
end
 
return simplestateexample