[metapost] description of glyph operator for MetaPost v1.200

Dan Luecking luecking at uark.edu
Wed May 6 22:43:44 CEST 2009

At 08:32 AM 5/6/2009, you wrote:
>I'd like to make sure the documentation of
>the new primitive is sufficiently clear for ordinary users to
>understand.  You can find a preview of the corresponding section at

Is the following really correct?

   "Clockwise oriented contours add to the shape of a glyph and are
    drawn in black ink. Counter-clockwise oriented contours erase
    parts of other contours, i.e., make them transparent again"

One normally thinks of counterclockwise as positive and clockwise
as negative. Also, do you really mean "drawn"? Should it be "filled"?
Also, counterclockwise is not hyphenated in my dictionary.

The following was completely mysterious to me on first reading:

   "As a side effect, erasing contours are opaque in the returned
    picture, while they were transparent in the original glyph."

It sounded like the paths themselves were being drawn (like unfill p;
draw p;). On further contemplation, it seems to mean

   "As a side effect, in the returned picture the interiors of the
    erasing contours are an opaque white, while they were transparent
    in the original glyph."

This has, of course, always been the case when a picture includes
"unfill p;". Surely that is documented somewhere and this should
include a reference to that. If that is not in the documentation
of unfill, it should be.


Daniel H. Luecking
Department of Mathematical Sciences
University of Arkansas
"Dubito ergo cogito, cogito ergo sum" --Descartes

More information about the metapost mailing list