public override IEnumerable <IHullPart> GetInflatedHullParts(
Pnt at, Pnt opposite, double offset, double inflate)
{
var part = new CircleHullPart(at, offset + inflate);
if (at.Dist2(opposite) < offset * offset)
{
part.Angle = Math.PI;
Pnt l = opposite - at;
part.StartDirection = Math.Atan2(l.X, -l.Y);
}
yield return(part);
}
