A round or chamfer whose edge chain runs on across a curved seam (the end circle of a lofted tube whose axis bends) is now built: the section solve keeps its contact on the seam through a plane taken afresh at the seam's nearest point at each step. Straight seams are unchanged. Robustness seed 41 is re-recorded: its second fillet, refused before, now builds. Fixes#1213.
Co-authored-by: gvocale <[email protected]>
Cutting one lofted round tube from another failed in truck's divide_face ("parameter boundary") for some section counts: the intersection points lie on the loft's seam, the previous point's parameter can sit a hair outside the range, and the Newton search from there fails.
The boundary is built as before; only when that returns None is it built again leniently, starting each search from the hint clamped into the parameter range and, as a last resort, searching the whole surface. Nothing that succeeds today changes. The boolean-retry guards are untouched.
Fixes 5 of the 6 failing hollow-elbow cases in #968 (new test crates/engine/src/tests/loft_cut.rs, volumes within 0.3% of exact). 90 degrees / 14 sections still fails in a later step and stays open in #968.
Walls swept along a spline have flat B-spline tops and bottoms, so booleans between them went to the general intersection, which fails on coincident spline faces. Such faces are now put on true planes, and two prisms of the same height and direction are decided in 2D with their spline outlines fitted by arcs within a micron. The result is kept only when its volume is plausible; otherwise the general boolean takes over. The free-form flag is cleared by a drop guard so an unwinding boolean can't leave it set.
Fixes#844.
find_close_pair's budget now counts the grid's own work too (each cell a triangle is filed under or visits), not only the pair tests, so a pathological pair of meshes can't spend unbounded time building and walking the grid. Adds tests for find_close_pair and the budget.
Giovanni