void ITreeEndVisitorOf <IShapePositioner> .EndVisit(IShapePositioner shapePositioner)
 {
     _posesStack.Pop();
     TryPopMaterial(shapePositioner);
 }
 void ITreeStartVisitorOf <IShapePositioner> .StartVisit(IShapePositioner shapePositioner)
 {
     PushPose(shapePositioner.Pose);
     TryPushMaterial(shapePositioner);
 }