Talk:OpenScad beginners tutorial

Can someone add an explanation of "normal" -- Ubuntourist 19:59, 20 November 2011 (CET) -- Ubuntourist 19:59, 20 November 2011 (CET)

I'm a bit thick. I added a definition for "surface normal" from Wikipedia but I'm not thrilled with it, since I'm not understanding exactly what it is or why it's needed. According to the definitions I've found, the "normal" appears to be a vector, but OpenSCAD and STL files use only a single point coordinate for the normal. Where's the other end? And why aren't the three points of a face sufficient? What does adding a "normal" provide?