pub fn bounded_half_space_in_frame(
boundary: &Rings,
plane: Plane3,
frame: PlaneFrame,
agreement: bool,
margin: ClipMargin,
tolerance: Tolerance,
) -> Result<TriMesh, GeomError>Expand description
Build a bounded half-space with an explicitly authored in-plane frame.
bounded_half_space derives the boundary’s in-plane axes from the clip
plane normal alone, which fixes only 2 of the 3 orientation degrees of
freedom: the rotation ABOUT the normal is picked by an internal heuristic.
That is fine when the profile carries no authored orientation of its own.
It is not fine when the source format authors one. IFC’s
IfcPolygonalBoundedHalfSpace.Position is an placement explicitly
independent of BaseSurface, and its PolygonalBoundary is expressed in
THAT frame. Deriving the axes instead of honouring the authored ones
silently rotates the clipping profile about the plane normal, so the wrong
region of the subject is cut.
The frame’s own axes are used as written. Its normal is not required to
match plane.normal: only the in-plane axes are taken from it, and the
sweep still runs along the clip plane’s normal, so an authored frame that
is tilted relative to the clip plane still contributes only its rotation
about that normal.
The frame’s origin anchors the boundary, projected onto the clip plane: an
in-plane offset from plane.origin moves the footprint by exactly that
offset, and the component along the normal is dropped so the sweep still
starts on the clip plane.