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dragengine:modules:dragonscript:behavior_triggered

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ECBehaviorTriggered

Behavior element behavior adding trigger support.

Adds a trigger expression to the behavior element. If the trigger expression changes value notifies the behavior element or other behaviors using listeners.

The default stub property name for the trigger expression is trigger if ID is empty or {id}.trigger if the ID is not empty. The stub property name can be changed which is typically done by ECBehavior using ECBehaviorTriggered in a composed way.

The initial state of the element is false. If the element is added to the game world notifyListeners() is only called if the trigger expression is true at this time.

Optionally a synchronized trigger can be specified. If set users of this trigger should use the synchronized trigger instead of this trigger. This allows setting a single trigger expression in an element stub to affect multiple triggers in the same element class.

Instance Counts

This behavior can be used multiple times on an element to add multiple triggers. Use the behavior identifier to tell them apart.

Element Class Properties

The default stub property name for the trigger expression is trigger if ID is empty or {id}.trigger if the ID is not empty. The stub property name can be changed which is typically done by ECBehavior using ECBehaviorTriggered in a composed way.

Events

triggerExpressionTrue

Trigger expression changed to true.

triggerExpressionFalse

Trigger expression changed to false.

Behavior Tree Actions

This behavior adds these behavior tree actions if behavior tree is present. Replace trigger by the value of propertyName if used.

trigger.check

Check one or more triggered trigger parameters. Action succeeds if all parameter value matches their respective triggered trigger parameter otherwise action fails. This action is typically used as first action in a sequence to run the sequence only if a triggered trigger parameter matches (or not).

ParameterValueDescription
statetrue, falseTrigger expression evaluates to true or false

This is an example of using this action:

<sequence>
  <action name='triggered.check'>
    <parameter name='state'>true</parameter>
  </action>
  <!-- actions here run only if trigger expression evaluates to true -->
</sequence>

Behavior Tree Conditions

This behavior adds these behavior tree conditions if behavior tree is present. Replace trigger by the value of propertyName if used.

trigger.check

Check one or more triggered trigger parameters. Conditions returns true if all parameter value match their respective triggered trigger parameter. This condition is typically used to run an action or sequence of actions as long as triggered trigger conditions are true.

ParameterValueDescription
triggered.statetrue, falseTrigger expression triggereds to true or false

This is an example of using this condition:

<action name='myAction' id='doing something'>
  <parameter name='triggered.state'>true</parameter>
  <condition>triggered.check</condition>
</action>

State Machine Actions

State Machine Conditions

State Machine Events

This behavior sends these state machine events. Replace trigger by the value of propertyName if used.

trigger.true

Trigger expression changed to true.

trigger.false

Trigger expression changed to false.

Required Behaviors

This behavior requires no other behaviors.

Optional Behaviors

Persistency

This behavior does not required element class to be persistable (setPersistable).

API Documentation

ECBehaviorTriggered.

Since DragonScript Module Version 1.0

Use Cases

  • Add trigger to element.

Element Class Example

This example defines an element which has a trigger.

class MyElement extends BehaviorElementClass
  public var ECBehaviorTriggered triggered
  func new()
    triggered = ECBehaviorTriggered.new(this)
  end
end

Behavior Factory

Using element class supporting adding behaviors the behavior can be added like this:

<?xml version='1.0' encoding='UTF-8'?>
<elementClass name='MyClass' class='GenericBehaviorElement'>
  <behavior type='ECBehaviorTriggered'>
    <!-- optional: use BaseGameApp trigger table. game can add more supported values.
                   default is 'default' -->
    <string name='triggerTable'>default</string>
 
    <!-- optional: name of trigger property. default is 'trigger' or 'trigger(id)'
                   depending if id is empty string or not. -->
    <string name='propertyName'>trigger</string>
 
    <!-- optional: identifier of ECBehaviorTriggered to synchronize with or empty
                   string to not synchronize. default is empty string. -->
    <string name='synchronize'>other</string>
 
    <!-- optional: use behavior tree with id instead of empty string -->
    <string name='behaviorTree'>second</string>
 
    <!-- optional: use state machine with id instead of empty string -->
    <string name='stateMachine'>second</string>
  </behavior>
 
  <!-- for adding multiple behaviors use unique identifiers -->
  <behavior type='ECBehaviorTriggered' id='second'/>
</elementClass>

Live Examples

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dragengine/modules/dragonscript/behavior_triggered.1746225424.txt.gz · Last modified: 2025/05/02 22:37 by dragonlord