An amazing and valuable worksheet. You remember the authors e-book "Creating Amazing Images with Mathcad (14)"? I sure have to give that sheet a closer look soon.
For hatching in 2D graphs I usually utilized a routine out of the book "Mathematik für Bauingenieure" by Grobstich and Strey. There used to be a preview of the book at google http://books.google.at/books?id=yyGdpWzo3v0C and the pages (347 & 348) with the hatch routine where included in that preview. But I just checked and saw that the preview is gone, so I think I am not allowed to post that hatch routine here.