function indexCurve(start, minX, minY, size) {
	    var p = start;
	    do {
	        if (p.z === null) p.z = zOrder(p.x, p.y, minX, minY, size);
	        p.prevZ = p.prev;
	        p.nextZ = p.next;
	        p = p.next;
	    } while (p !== start);
	
	    p.prevZ.nextZ = null;
	    p.prevZ = null;
	
	    sortLinked(p);
	}
// interlink polygon nodes in z-order
interlink polygon nodes in z-order
interlink polygon nodes in z - order
function indexCurve(start, minX, minY, size) {
	    var p = start;
	    do {
	        if (p.z === null) p.z = zOrder(p.x, p.y, minX, minY, size);
	        p.prevZ = p.prev;
	        p.nextZ = p.next;
	        p = p.next;
	    } while (p !== start);
	    p.prevZ.nextZ = null;
	    p.prevZ = null;
	    sortLinked(p);
	}
function indexCurve ( start , minX , minY , size ) { var p = start ; do { if ( p . z === null ) p . z = zOrder ( p . x , p . y , minX , minY , size ) ; p . prevZ = p . prev ; p . nextZ = p . next ; p = p . next ; } while ( p !== start ) ; p . prevZ . nextZ = null ; p . prevZ = null ; sortLinked ( p ) ; }
interlink polygon nodes in z-order
interlink polygon nodes in z - order