void FindBeforeAfterV(VisibilityVertex v, RbTree <VisibilityVertex> nodeBoundaryRbTree,
out VisibilityVertex beforeV, out VisibilityVertex afterV, Point center)
{
Point xDir = new Point(1, 0);
var vAngle = Point.Angle(xDir, v.Point - center);
var rNode = nodeBoundaryRbTree.FindLast(w => Point.Angle(xDir, w.Point - center) <= vAngle);
beforeV = rNode != null ? rNode.Item : nodeBoundaryRbTree.TreeMaximum().Item;
rNode = nodeBoundaryRbTree.FindFirst(w => Point.Angle(xDir, w.Point - center) >= vAngle);
afterV = rNode != null ? rNode.Item : nodeBoundaryRbTree.TreeMinimum().Item;
}
void FindBeforeAfterV(VisibilityVertex v, RbTree<VisibilityVertex> nodeBoundaryRbTree,
out VisibilityVertex beforeV, out VisibilityVertex afterV, Point center) {
Point xDir=new Point(1,0);
var vAngle = Point.Angle(xDir, v.Point - center);
var rNode = nodeBoundaryRbTree.FindLast(w => Point.Angle(xDir, w.Point - center) <= vAngle);
beforeV = rNode!=null? rNode.Item : nodeBoundaryRbTree.TreeMaximum().Item;
rNode = nodeBoundaryRbTree.FindFirst(w => Point.Angle(xDir, w.Point - center) >= vAngle);
afterV = rNode != null ? rNode.Item : nodeBoundaryRbTree.TreeMinimum().Item;
}
