Function boolean_2d 

pub fn boolean_2d(
    subject: &[Ring2D],
    clip: &[Ring2D],
    op: BooleanOp2D,
) -> ContourSet

Apply a boolean operation to two contour sets.

Ring winding carries outer-vs-hole (see the module docs); the fill rule is always NonZero. Never panics: degenerate rings are dropped and every empty combination has a defined answer —

subject	clip	union	difference	intersection
empty	any	clip	empty	empty
any	empty	subj	subj	empty

where “clip”/“subj” mean that operand resolved into disjoint shapes.