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dragengine:modules:dragonscript:behavior_attachslot

ECBehaviorAttachSlot

Behavior element behavior adding support to attach other behavior elements.

Provides an attachment slot where one ECBehaviorAttachable supporting element can be attached to. The slot behavior is responsible to persist the UniqueID of the attachable. Attachable is added to game world during addToGameWorld() if not in the game world already. Attachable is remove from game world during removeFromGameWorld() if in the game world. If attachable is present while behavior instance is disposed then attachable will be safely disposed using Element.safeDispose() .

Behavior supports using ECBehaviorVRHand instead of ECBehaviorCollider to add attachment slot to VR hands.

Instance Counts

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

Element Class Properties

Element class properties have the prefix attachSlot. or attachSlot({id}). if id is not empty.

bone

Set bone to attach to or empty string to attach to collider.

  • Full name: attachSlot.bone or attachSlot({id}).bone
  • Type: string
  • Default Value: empty string
  • Example (*.deeclass)
    <string name='attachSlot.bone'>value</string>

position

Set position in meters to attach to.

  • Full name: attachSlot.position or attachSlot({id}).position
  • Type: 3-component float vector
  • Default Value: (0,0,0)
  • Example (*.deeclass)
    <vector name='attachSlot.position' x='0' y='0' z='0.2'/>

orientation

Set orientation in degrees to attach to.

  • Full name: attachSlot.orientation or attachSlot({id}).orientation
  • Type: 3-component float vector
  • Default Value: (0,0,0)
  • Example (*.deeclass)
    <vector name='attachSlot.orientation' x='90' y='0' z='0'/>

Events

This behavior has these events:

slotAttached

Attachable has been attached to slot.

slotDetached

Attachable has been removed from slot.

Behavior Tree Actions

This behavior adds these behavior tree actions if behavior tree is present. If behavior has non-empty identifier replace attachSlot with attachSlot(id).

attachSlot.detach

Detach attachable if one is present.

ParameterValueDescription
dispose Dispose of attachable after detaching it

This is an example of using this action:

<action name='attachSlot.detach'>
  <parameter name='dispose'/>
</action>

attachSlot.check

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

ParameterValueDescription
emptytrue, falseAttach slot is empty or not
wait If present action returns BTResult.running instead of BTResult.failed to wait until the checks are all fulfilled

This is an example of using this action:

<sequence>
  <action name='attachSlot.check'>
    <parameter name='empty'>false</parameter>
  </action>
  <!-- actions here run only if attach slot is not empty, hence an attachable is present -->
</sequence>

Behavior Tree Conditions

This behavior adds these behavior tree conditions if behavior tree is present. If behavior has non-empty identifier replace attachSlot with attachSlot(id).

attachSlot.check

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

ParameterValueDescription
attachSlot.emptytrue, falseAttach slot is empty or not

This is an example of using this condition:

<action name='myAction' id='doing something'>
  <parameter name='attachSlot.empty'>false</parameter>
  <condition>attachSlot.check</condition>
</action>

State Machine Actions

State Machine Conditions

State Machine Events

This behavior sends these state machine events. If behavior has non-empty identifier replace attachSlot with attachSlot(id).

attachSlot.attached

Attachable has been attached to slot

attachSlot.detached

Attachable has been removed from slot.

Required Behaviors

This behavior requires no other behaviors.

Optional Behaviors

Persistency

This behavior does support element class to be persistable (setPersistable).

API Documentation

ECBehaviorAttachSlot.

Since DragonScript Module Version 1.0

Use Cases

Element Class Example

This example defines an element which contains an attachment slot.

class MyElement extends BehaviorElementClass
  public var ECBehaviorComponent component
  public var ECBehaviorCollider collider
  public var ECBehaviorAttachSlot attachSlot
  func new()
    component = ECBehaviorComponent.new(this, null)
    collider = ECBehaviorCollider.new(this, component)
    attachSlot = ECBehaviorAttachSlot.new(this, collider)
  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='ECBehaviorComponent'/>
  <behavior type='ECBehaviorCollider'/>
 
  <behavior type='ECBehaviorAttachSlot'>
    <!-- optional: use vrhand behavior with id. if not set ECBehaviorCollider is used -->
    <string name='vrHand'>right</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>
 
    <!-- set element properties. omit property prefix if used inside behavior tag -->
    <string name='.bone'>hand.attach.l</string>
  </behavior>
 
  <!-- for adding multiple behaviors use unique identifiers -->
  <behavior type='ECBehaviorAttachSlot' id='second'/>
</elementClass>

Live Examples

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dragengine/modules/dragonscript/behavior_attachslot.txt · Last modified: 2025/05/04 13:46 by dragonlord