Fix NPE. Add scene panel.

Author: calvertdw

ihmc-high-level-behaviors/src/libgdx/java/us/ihmc/rdx/behaviorTree/RDXBehaviorTree.java

@@ -54,7 +54,7 @@ public RDXBehaviorTree(WorkspaceResourceDirectory treeFilesDirectory,ROS2SyncedR
    {
       super(syncedRobot, ROS2ActorDesignation.OPERATOR, peerClockEstimator, treeFilesDirectory, new RDXBehaviorTreeNodeBuilder());
 
-      scene = new RDXBehaviorTreeScene();
+      scene = new RDXBehaviorTreeScene(panel);
 
       ((RDXBehaviorTreeNodeBuilder) getNodeBuilder()).initialize(crdtInfo,
                                                                  saveFileDirectory,

ihmc-high-level-behaviors/src/libgdx/java/us/ihmc/rdx/behaviorTree/scene/RDXBehaviorTreeScene.java

@@ -1,7 +1,19 @@
 package us.ihmc.rdx.behaviorTree.scene;
 
 import us.ihmc.behaviors.behaviorTree.scene.BehaviorTreeSceneState;
+import us.ihmc.rdx.imgui.RDXPanel;
 
 public class RDXBehaviorTreeScene extends BehaviorTreeSceneState
 {
+   private final RDXPanel panel = new RDXPanel("Scene", this::renderImGuiWidgets);
+
+   public RDXBehaviorTreeScene(RDXPanel parentPanel)
+   {
+      parentPanel.addChild(panel);
+   }
+
+   private void renderImGuiWidgets()
+   {
+
+   }
 }

ihmc-high-level-behaviors/src/main/java/us/ihmc/behaviors/behaviorTree/scene/BehaviorTreeSceneState.java

@@ -32,6 +32,6 @@ public List<BehaviorTreeSceneObject> getObjects()
 
    public ReferenceFrameLibrary getReferenceFrameLibrary()
    {
-      return null;
+      return referenceFrameLibrary;
    }
 }