Behavior adding support to define grab spot for actors.

Defines position and orientation where the actor can grab the owner element. Grab spots are typically used for physics interaction like VR hand use but can be used also with mouse interaction. The actual grabbing interaction, exact grab location and orientation as well as attaching logic is handled by other behaviors using listening. This behavior also tracks if an actor is grabbing the grab spot. Hence at most one actor can grab an grab spot at each time.

Elements able to grab a grab spot have to use the ECBehaviorGrabber behavior. Both the grab spot and the grabber have to persist the other behavior. During restoring no notifications are triggered this way.

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

Element class properties have the prefix grabSpot. or grabSpot(id). if id is not empty.

Physics type of touch collider used to detect touching grabbers.

• Full name: grabSpot.touchCollider.physicsType or grabSpot(id).touchCollider.physicsType
• Type: enumeration

• Allowed Values:

  Value	Description
  none	Collider is not moving and will not move by collisions.
  dynamic	Collider reacts to impacts using physical simulation.
  kinematic	Game scripts define the collision response.

• Default Value: kinematic
• Example (*.deeclass):

  <string name='grabSpotright).touchCollider.physicsType>kinematic</string>

Local gravity of touch collider if not affected by world gravity.

• Full name: grabber.touchCollider.localGravity or grabber(id).touchCollider.localGravity
• Type: 3-component vector
• Default Value: (0, 0, 0)
• Example (*.deeclass):

  <vector name='grabSpot(right).touchCollider.localGravity' x='0' y='-0.1' z='0'/>

Weight (mass) of touch collider if dynamic.

• Full name: grabber.touchCollider.weight or grabber(id).touchCollider.weight
• Type: float
• Default Value: 1
• Example (*.deeclass):

  <float name='grabSpot(right).touchCollider.weight'>0.2</float>

Initial enabled state of touch collider.

• Full name: grabber.touchCollider.enabled or grabber(id).touchCollider.enabled
• Type: boolean
• Default Value: true
• Example (*.deeclass):

  <boolean name='grabSpot(right).touchCollider.enabled'>true</float>

Shape of touch collider used to detect grabbers.

• Full name: grabSpot.touchCollider.shape or grabSpot(id).touchCollider.shape
• Type: string (shape format). See “Shape List Encoding” in CodecPropertyString.
• Default Value: empty string
• Example (*.deeclass):

  <string name='grabber(right).touchCollider.shape'>box:extends,0.1,0.1,0.1</string>

Rig resource to use for touch collider.

• Full name: grabSpot.touchCollider.rig or grabSpot(id).touchCollider.rig
• Type: string
• File Pattern: *.derig (all rig modules)
• Default Value: empty path
• Example (*.deeclass):

  <string name='grabSpot(right).touchCollider.rig'>grab_spot.derig</string>

Touch collider attach position relative to parent element or bone.

• Full name: grabSpot.position or grabSpot(id).position
• Type: 3-component vector
• Default Value: (0, 0, 0)
• Example (*.deeclass):

  <vector name='grabSpot(right).position' x='0' y='0' z='0.1'/>

Touch collider attach orientation in euler degrees relative to parent element or bone.

• Full name: grabSpot.rotation or grabSpot(id).rotation
• Type: 3-component vector
• Default Value: (0, 0, 0)
• Example (*.deeclass):

  <vector name='grabSpot(right).rotation' x='-45' y='0' z='0'/>

Name of bone to attach touch collider to or empty string to attach to the parent element.

• Full name: grabSpot.bone or grabSpot(id).bone
• Type: string
• Default Value: empty string
• Example (*.deeclass):

  <string name='grabSpot(right).bone'>attach hand.r</string>

Grabber has grabbed spot.

Grabber has release spot.

Grab spot enabled changed.

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

Set one or more grab spot parameters.

This is an example of using this action:

<action name='grabSpot.set'>
  <parameter name='enabled'>true</parameter>
</action>

Release grabber if one is grabbing the grab spot.

This is an example of using this action:

<action name='grabSpot.release'/>

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

This is an example of using this action:

<sequence>
  <action name='grabSpot.check'>
    <parameter name='grabbed'>true</parameter>
  </action>
  <!-- actions here run only if grab spot is grabbed by a grabber -->
</sequence>

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

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

This is an example of using this condition:

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

Same as Behavior Tree Actions.

Same as Behavior Tree Conditions.

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

Grab spot has been enabled.

Grab spot has been disabled.

Grabber grabbed grab spot.

Grabber released grab spot.

This behavior does not required other behaviors to be present.

• ECBehaviorCollider: If used attaches grab spot touch collider to collider
• ECBehaviorBehaviorTree: Add actions and conditions for behavior trees to use.
• ECBehaviorStateMachine: Add actions and conditions for state machine to use and events to send to the state machine.

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

ECBehaviorGrabSpot.

Since DragonScript Module Version 1.9

• Allow player to grab objects in VR with his hands.
• Add different grab spots on an object in VR to alter the interactions the player can do.

class ExampleElementClass extends BehaviorElementClass
   public var ECBehaviorComponent component
   public var ECBehaviorCollider collider
   public var ECBehaviorGrabSpot grabSpot
   
   public func new() super("ExampleElement")
      // Create component and collider to give element a look and feeling
      component = ECBehaviorComponent.new(this)
      collider = ECBehaviorCollider.new(this, component)
      
      // Create grab spot 10cm along Z axis
      grabSpot = ECBehaviorGrabSpot.new(this, collider)
      grabSpot.getAttachTouchCollider().getPosition().setVector(Vector.new(0, 0, 0.1))
   end
end

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='ECBehaviorGrabSpot'>
    <!-- optional: set collision filter. default value '4:1' which means
                   category BaseGameApp.CollisionFilterBit.trigger
                   filter BaseGameApp.CollisionFilterBit.dynamic.
                   format is '', 'category' or 'category:filter' where category and filter
                   are a list of bits to set. -->
    <string name='collisionFilter'>4:1 2</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='.name'>Color 1</string>
  </behavior>
 
  <!-- for adding multiple behaviors use unique identifiers -->
  <behavior type='ECBehaviorGrabSpot' id='second'/>
</elementClass>

• DEExamples Repository: ExampleVR project.