{{tag>dragonscript behavior}}
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[[:start|Start Page]] >> [[main|DragonScript Scripting Language]] >> [[dragengine:modules:dragonscript:abstractions|Abstraction Layers: How you want to build your Game]] >> [[dragengine:modules:dragonscript:behavior_elements|Behavior Elements]] >> **ECBehaviorRenderableCustomColor**
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  * [[behaviors_use_cases|Behaviors Explained: By Use-Case]]
  * [[behaviors_a_to_z|Behaviors Explained: From A to Z]]

====== ECBehaviorVRHMD ======

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Behavior element behavior adding VR HMD support to actor. This behavior tracks the HMD position and orientation and if it is attached or not.

====== Instance Counts ======

This behavior can be used only once on an element.

====== Element Class Properties ======

This behavior has no element class properties.

====== Events ======

===== hmdAttached =====

HMD attached and ready to use.

===== hmdDetached =====

HMD detached and no more usable.

====== Behavior Tree Actions ======

This behavior adds these behavior tree actions if behavior tree is present.

===== vrhmd.check =====

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

^Parameter^Value^Description^
|attached|''true'', ''false''|VR HMD is attached and usable|
|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:
<code xml>
<sequence>
  <action name='vrhmd.check'>
    <parameter name='attached>true</parameter>
  </action>
  <!-- actions here run only if VR HMD is attached and usable -->
</sequence>
</code>

====== Behavior Tree Conditions ======

This behavior adds these behavior tree conditions if behavior tree is present.

===== vrhmd.check =====

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

^Parameter^Value^Description^
|vrhmd.attached|''true'', ''false''|VR HMD is attached and usable|

This is an example of using this condition:
<code xml>
<action name='myAction' id='doing something'>
  <parameter name='vrhmd.attached'>true</parameter>
  <condition>vrhmd.check</condition>
</action>
</code>

====== State Machine Actions ======

Same as [[#behavior_tree_actions|Behavior Tree Actions]].

====== State Machine Conditions ======

Same as [[#behavior_tree_conditions|Behavior Tree Conditions]].

====== State Machine Events ======

This behavior sends no state machine events.

====== Required Behaviors ======

  * [[behavior_vrplayspace|ECBehaviorVRPlayspace]]

====== Optional Behaviors ======

  * [[behavior_behaviortree|ECBehaviorBehaviorTree]]: Add actions and conditions for behavior trees to use.
  * [[behavior_statemachine|ECBehaviorStateMachine]]: Add actions and conditions for state machine to use and events to send to the state machine.

====== Persistency ======

This behavior does not use persistency.

====== API Documentation ======

#@LinkApiDocDEDS2_HTML~classDragengine_1_1Scenery_1_1ECBehaviorVRHMD.html,ECBehaviorVRHMD~@#.

Since DragonScript Module Version ''1.6''

====== Use Cases ======

  * Attach in-game camera to HMD. Required to see rendered scene in the HMD.

====== Element Class Example ======

The following example creates an element class supporting HMD being driven by actor:

<code>
class MyElement extends BehaviorElementClass
  public func new()
    // Add VR Playspace behavior. Base behavior required by all VR behaviors
    var ECBehaviorVRPlayspace vrPlayspace = ECBehaviorVRPlayspace.new(this)
    
    // Add VR HMD behavior. With this behavior present VRPlayerControlledActorCameraDirector
    // can attach the HMD to the in-game camera
    ECBehaviorVRHMD.new(this, vrPlayspace)
  end
end
</code>

====== Behavior Factory ======

Using element class supporting adding behaviors the behavior can be added like this:
<code xml>
<?xml version='1.0' encoding='UTF-8'?>
<elementClass name='MyClass' class='GenericBehaviorElement'>
  <behavior type='ECBehaviorVRPlayspace'/>
  
  <behavior type='ECBehaviorVRHMD'>
    <!-- optional: use BaseGameApp binding manager. game can add more supported values -->
    <string name='bindingManager'>default</string>
    
    <!-- optional: add behavior trees. default adds all behavior trees. -->
    <list name='behaviorTrees'>
      <string/> <!-- add behavior with empty identifier -->
      <string>default</string> <!-- add behavior with 'default' identifier -->
    </list>
    
    <!-- optional: add state machines. default adds all state machines. -->
    <list name='stateMachines'>
      <string/> <!-- add behavior with empty identifier -->
      <string>default</string> <!-- add behavior with 'default' identifier -->
    </list>
  </behavior>
</elementClass>
</code>

====== Live Examples ======

  * [[https://github.com/LordOfDragons/deexamples|DEExamples Repository]]: ExampleVR project.