pub fn reduce_degree2(
curve: &BSplineCurve2,
tolerance: Scalar,
) -> GeomResult<BoundedResult<BSplineCurve2>>Expand description
Lower a planar curve’s degree by one, or refuse.
Lossy in general: only a curve that was already representable at the lower degree reduces cleanly. An elevated curve is the clean case, and reduction recovers what it started from.
Same discipline as knot removal: compute, measure, and refuse when the
deviation exceeds tolerance, rather than trusting the reduction formula
on a curve that genuinely needs its degree.