question: protected void initSimulator ( ForceSimulator fsim ) { TupleSet ts = m_vis . getGroup ( m_nodeGroup ) ; if ( ts == null ) return ; try { ts . addColumns ( FORCEITEM_SCHEMA ) ; } catch ( IllegalArgumentException iae ) { } float startX = ( referrer == null ? 0f : ( float ) referrer . getX ( ) ) ; float startY = ( referrer == null ? 0f : ( float ) referrer . getY ( ) ) ; startX = Float . isNaN ( startX ) ? 0f : startX ; startY = Float . isNaN ( startY ) ? 0f : startY ; Iterator iter = m_vis . visibleItems ( m_nodeGroup ) ; while ( iter . hasNext ( ) ) { VisualItem item = ( VisualItem ) iter . next ( ) ; ForceItem fitem = ( ForceItem ) item . get ( FORCEITEM ) ; fitem . mass = getMassValue ( item ) ; double x = item . getEndX ( ) ; double y = item . getEndY ( ) ; fitem . location [ 0 ] = ( Double . isNaN ( x ) ? startX : ( float ) x ) ; fitem . location [ 1 ] = ( Double . isNaN ( y ) ? startY : ( float ) y ) ; fsim . addItem ( fitem ) ; } if ( m_edgeGroup != null ) { iter = m_vis . visibleItems ( m_edgeGroup ) ; while ( iter . hasNext ( ) ) { EdgeItem e = ( EdgeItem ) iter . next ( ) ; NodeItem n1 = e . getSourceItem ( ) ; ForceItem f1 = ( ForceItem ) n1 . get ( FORCEITEM ) ; NodeItem n2 = e . getTargetItem ( ) ; ForceItem f2 = ( ForceItem ) n2 . get ( FORCEITEM ) ; float coeff = getSpringCoefficient ( e ) ; float slen = getSpringLength ( e ) ; fsim . addSpring ( f1 , f2 , ( coeff >= 0 ? coeff : - 1.f ) , ( slen >= 0 ? slen : - 1.f ) ) ; } } }
target:  Loads the simulator with all relevant force items and springs.