出典:Wikipedia
出典:『Wikipedia』 (2011/05/05 08:09 UTC 版)
A prismatic surface is a surface generated by all the lines that are parallel to a given line and intersect a broken line that is not in the same plane as the given line. The broken line is the directrix of the surface; the parallel lines are its generators (or elements). If the broken line is closed (i.e. a closed polygon), then the surface is a closed prismatic surface.