for offset2() with clear meaning.
New ClipperUtils functions: expand(), shrink() as an alternative
for offset() with clear meaning.
All offset values for the new functions are positive.
Various offsetting ClipperUtils (offset, offset2, offset2_ex) working
over Polygons were marked as unsafe, sometimes producing invalid output
if called for more than one polygon. These functions were reworked
to offset polygons one by one. The new functions working over Polygons
shall work the same way as the old safe ones working over ExPolygons,
but working with Polygons shall be computationally more efficient.
Improvements in FDM support generator:
1) For both grid and snug supports: Don't filter out supports for which
the contacts are completely reduced by support / object XY separation.
2) Rounding / merging of supports using the closing radius parameter is
now smoother, it does not produce sharp corners.
3) Snug supports: When calculating support interfaces, expand the projected
support contact areas to produce wider, printable and more stable interfaces.
4) Don't reduce support interfaces for snug supports for steep overhangs,
that would normally not need them. Snug supports often produce very
narrow support interface regions and turning them off makes the support
interfaces disappear.
Fixes Solid infill where there should be none #6482
Also the safety offsetting was revised to be enabled only where needed,
the "do safety offset" is now easy to discover by
a new ApplySafetyOffset::Yes enum, and safety offset over union, which
is better done by offset() / offset_ex() has been replaced with
new union_safety_offset() / union_safety_offset_ex() functions, which
better convey their meaning and which could be better optimized than
union() with the safety offset applied.
which was broken with 68666de521b1cb15e41ac6728c0e8d3b4b0d4ed0
"Reworked the "new" bridging to respect the bridge_flow_ratio
by maintaining extrusion spacing, but modifying the extrusion width
and / or height."
Fixed some issues in internal anchors of the Adaptive Cubic infill.
The ugly and dangerous implicit casting operators in Line, MultiPoint,
Polyline and Polygon were made explicit.
1) Octree is built directly from the triangle mesh by checking
overlap of a triangle with an octree cell. This shall produce
a tighter octree with less dense cells.
2) The same method is used for both the adaptive / support cubic infill,
where for the support cubic infill the non-overhang triangles are
ignored.
The AABB tree is no more used.
3) Optimized extraction of continuous infill lines in O(1) instead of O(n^2)
