Hi,
The Geometry.Line3d (unbounded) or Geometry.LineSegment3d (bounded) have an IntersectWith method.
So, a .NET equivalent for the inters function may be something like this:
public Point3d[] Inters(Point3d p1, Point3d p2, Point3d p3, Point3d p4, bool onSeg)
{
LinearEntity3d l1, l2;
if (onSeg)
{
l1 = new LineSegment3d(p1, p2);
l2 = new LineSegment3d(p3, p4);
}
else
{
l1 = new Line3d(p1, p2);
l2 = new Line3d(p3, p4);
}
return l1.IntersectWith(l2);
}