/// <summary>
/// Sets the index-th edge of this polygon.
/// </summary>
public static IImmutablePolygon <V2d> SetEdge(this IImmutablePolygon <V2d> self, int index, Line2d edge)
{
index = self.RepairIndex(index);
var i0 = index++;
var i1 = index < self.Count ? index : 0;
return(self.SetPoint(i0, edge.P0).SetPoint(i1, edge.P1));
}
/// <summary>
/// Gets the index-th edge of this polygon.
/// </summary>
public static Line2d GetEdge(this IImmutablePolygon <V2d> self, int index)
{
index = self.RepairIndex(index);
var p0 = self.Points[index++];
var p1 = self.Points[index < self.Count ? index : 0];
return(new Line2d(p0, p1));
}