separate groups. The section is swept normal to the trajectory,
producing a mesh. I'm doing the triangles only now, not copying
over any entities.
Also fix a bug in the PNG export; rows are 4-aligned, so that was
breaking when the width of the image wasn't divisible by four. Also
fix a bug in lathes, where it generated overlapping triangles for
one segment.
And change the groups to record both "this mesh", the contribution
due to the extrude/lathe/whatever, and the "running mesh", that we
get after applying the requested Boolean op between "this mesh" and
the previous group's "running mesh". I'll use that to make step and
repeats step the mesh too.
[git-p4: depot-paths = "//depot/solvespace/": change = 1801]
an Expr *, since that complicates multiple units and also memory
management. Now it's just a double.
[git-p4: depot-paths = "//depot/solvespace/": change = 1791]
and requests to a separate list. It's messy, because I have to make
a deep copy (e.g. of the remap list for the groups, or Expr *
stuff) of some things. Others (e.g. the polygon or mesh) will be
regenerated, so they should be discarded, but they must not get
double-freed.
In any case, works superficially. And fix a few memory leaks
unrelated to this, and remove some dead code.
[git-p4: depot-paths = "//depot/solvespace/": change = 1775]