The MetaPost system implements a picture-drawing language very much like that of METAFONT except that it outputs PostScript commands instead of run-length-encoded bitmaps. MetaPost is a powerful language for producing figures for documents to be printed on PostScript printers. It provides access to all the features of PostScript and it includes facilities for integrating text and graphics. (Knuth tells us that he uses nothing else for diagrams in text that he is writing.)
Much of MetaPost's source code was copied from METAFONT's sources with Knuth's permission.