PLink draws piecewise linear link projections. Components may be
points, PL arcs, or PL circles. Line segments are oriented consistently in
each component. Different components are different colors.
Once you’ve drawn the link, select the menu item “PLink->Tools->Send to
SnapPy”, and then M will be the complement of the link. If you edit
the link, you can again do “Send to SnapPy” to update M.
The window can be resized to allow for different sizes of link
projections, and the arrow keys can be used to slide the projection
around in order to make more room on one side or another.
The “Tools” menu can be used to make the projection alternating
(provided that all components are circles), or to clear the screen,
or to reflect the projection in the xy-plane, changing all crossings.
Also, the “Tools” menu includes the “send to SnapPy” command.
The “File” menu can be used to save the projection as a SnapPea
link projection file. (This can be done from the drawing state as
well, in which case the “hot vertex” is remembered in the file!). The
“File->Open File” command will read a SnapPea link projection file,
and restart drawing if the projection was saved while drawing.
The “Info” menu selects information about the link projection to be
displayed in the info line at the bottom. Various encoding schemes
for link projections are supported, as well as the blackboard framing
curves, expressed in meridian-longitude coordinates. Cutting and
pasting from the info line is supported. The numerical and
alphabetical Dowker-Thistlethwaite codes are displayed in an extended
form which includes a full description of the planar embedding. The
string printed in the info line is also accepted as input to SnapPy’s
Manifold constructor. That is, you can paste the complete DT code,
DT: [(-4,6,2)], [0,0,1], between the apostrophes in
Manifold(‘’). The “DT labels” option displays the indexing used in
computing the Dowker-Thistlethwaite codes.