title: Convert 3D plane (front view of a solid) to 2D coordinates (XY plane)
body: <p>in my program, I have a solid in top view which I cut using cutting plane (by drawing a line on top view - XY plane). After the solid is cut using this line, I have to show the front face of the cut part on XY plane so I can print the diagram of cross section on paper. So once I have a rectangle of cut face (in front view - XZ plane) and I have to transform it to show in XY plane. How can I do this using VB.net.</p>
  
  <p>I saw this question here: <a href="https://stackoverflow.com/questions/23814234/convert-3d-plane-to-2d">convert 3D plane to 2D</a>
  and code provided by user Kieth.
  Is this solution relevant to my problem?</p>
  
  <p>Edit: This edit is related to Nico Schertler's answer. I read up on vectors and basic coordinate geometry. how should I get direction vector? For example, the cut line that cuts my solid cube is defined by: stPt(-1500, 24038, 0) and edPt(45500, 24038, 0). The cut face of the solid is rectangle: pt1(-350, 24038, 0), pt2(1335, 24038, 0), pt3(1335, 24038, -350) and pt4(-350, 24038, -350). 
  I have to transform each coordinate of this rectangle, so that it is lying in XY plane. Currently it is XZ plane. So here, the direction vector is the direction of cut line or each edge of the rectangle? I hope I am not confusing anyone.</p>