How to find the intersection point between the invisible frame of `\rput` and the line segment of `\ncline`?

Question

Points enclosed by black ovals are the intersection points between the frame boundary of \rput and the line segment of \ncline.

How to find these points?

---

The screenshot above is copied from PSTricks Tutorial series on page 4.

Answer 1

\documentclass{article} 
\usepackage{pst-node}\SpecialCoor
\makeatletter
\def\psGetEdgeA#1#2{tx@NodeDict begin 0.0 0.0 neg 0.0 0.0 0 0 
  /N@#1 /N@#2 InitNC { NCCoor } if pop pop \tx@UserCoor end}
\def\psGetEdgeB#1#2{tx@NodeDict begin 0.0 0.0 neg 0.0 0.0 0 0 
  /N@#1 /N@#2 InitNC { NCCoor } if 4 2 roll pop pop \tx@UserCoor end}
\makeatother

\begin{document}
\Huge
\hspace*{4cm}\rnode{B}{Node B}

\vspace{2cm}
\rnode{A}{Node A}
\ncline{A}{B}
\pscircle*[linecolor=blue,opacity=0.4](!\psGetEdgeA{A}{B}){10pt}
\pscircle*[linecolor=blue,opacity=0.4](!\psGetEdgeB{A}{B}){10pt}

\end{document}