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
There is provision in MetaPost for avoiding this problem: issue the commandError: /undefined in cmmi10
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:
or by issuing a shell command such asprologues := 2; input MyFigure
(which will work without the quote marks if you're not using a Unix shell).mp '\prologues:=2; input MyFigure'
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
would then give a satisfactory Encapsulated PostScript file. This procedure may be automated using the Perl script mps2eps, thus saving a certain amount of tedium.dvips -E -o MyFigure.eps MyFigure
The Plain TeX user may use an adaptation of a jiffy of Knuth's, by Dan Luecking. Dan's version mpsproof.tex will work under TeX to produce a DVI file for use with dvips, or under PDFTeX to produce a PDF file, direct. The output is set up to look like a proof sheet.
A script application, mptopdf, is available in recent (La)TeX distributions: it seems fairly reliably to produce PDF from MetaPost, so may reasonably be considered an answer to the question...
This question on the Web: http://www.tex.ac.uk/cgi-bin/texfaq2html?label=mpprologues