PicTeX is an early, and very comprehensive drawing package,
that mostly draws by placing myriads of small dots to make up
pictures. It has a tendency to run out of space, most
especially of allowable dimensions registers; packages m-pictex
and pictexwd deal with the register problem, in different ways.
Note that full documentation may be bought via the PC-TeX site,
though a command summary is available as free software.
Alternatively, a front-end package such as mathsPiC, which
covers all of PicTeX and has a complete and free manual, could
be used.