Mfpic is a scheme for producing pictures from (La)TeX commands.
Commands \mfpic and \endmfpic (in LaTeX, the mfpic environment)
enclose a group in which drawing commands may be placed. The
commands generate a Meta-language file, which may be processed
by Metapost (or even Metafont). The resulting image file will
be read back in to the document to place the picture at the
point where the original (La)TeX commands appeared. Note that
the ability to use Metapost here means that the package works
equally well in LaTeX and PDFLaTeX.

Homepage:
https://ctan.org/pkg/mfpic
