public void StopAttracting()
 {
     if (nodeAttractionDefinition != null)
     {
         ForceDefinitions.Remove(nodeAttractionDefinition);
         nodeAttractionDefinition = null;
     }
 }
 public void StartAttracting()
 {
     nodeAttractionDefinition = new NodeAttractionDefinition();
     ForceDefinitions.Add(nodeAttractionDefinition);
 }