MetaPost ordinarily expects its output to be included in some context where the 'standard' Metafont fonts (that you've specified) are already defined - for example, as a figure in TeX document. If you're debugging your MetaPost code, you may want to view it in ghostscript (or some other PostScript previewer). However, the PostScript 'engine' in ghostscript doesn't ordinarily have the fonts loaded, and you'll eperience an error such as
Error: /undefined in cmmi10There is provision in MetaPost for avoiding this problem: issue the command
prologues := 2; at the start of the .mp file.
Unfortunately, the PostScript that MetaPost inserts in its output,
following this command, is incompatible with ordinary use of the
PostScript in inclusions into (La)TeX documents, so it's best to
make the prologues command optional. Furthermore, MetaPost takes a
very simple-minded approach to font encoding: since TeX font
encodings regularly confuse sophisticated minds, this can prove
troublesome. If you're suffering such problems (the symptom is that
characters disappear, or are wrongly presented) the only solution is
to view the 'original' metapost output after processing through
LaTeX and dvips.
Conditional compilation may be done either by inputting MyFigure.mp indirectly from a simple wrapper MyFigureDisplay.mp:
prologues := 2; input MyFigureor by issuing a shell command such as
mp '\prologues:=2; input MyFigure'(which will work without the quote marks if you're not using a Unix shell).
A suitable LaTeX route would involve processing MyFigure.tex, which contains:
\documentclass{article}
\usepackage{graphicx}
\begin{document}
\thispagestyle{empty}
\includegraphics{MyFigure.1}
\end{document}
Processing the resulting DVI file with the dvips
command
dvips -E -o MyFigure.eps MyFigurewould then give a satisfactory Encapsulated PostScript file.