Contour

The names of the product elements

The name of the type

Builds a contour, copying the points into an immutable Vector.

This apply replaces the case-class-generated one, and the copy is the whole point of that: retaining the caller's Seq by reference would make the lazy metrics observe a mutable buffer's later edits, and a List would make convexHull's per-vertex indexing quadratic. Vector.toVector is the same instance, so contours built from already-immutable data pay nothing. The remaining way to hand in a sequence by reference is new Contour(...) or copy(points = ...) — explicit, not the default.