Parallel projection of spline curves onto plane

I'm trying to project a wire onto a plane. What I need are 2d curves. My approach so far is the following:
-retrieve the 3d-curve of every edge in the wire
-project the curve onto the plane using ProjLib_ProjectOnPlane
-create a 2d curve adaptor using ProjLib_ProjectedCurve.

The problem is that ProjLib_ProjectedCurve obviously cannot project splines. In the code, there are only empty switch cases:

[code]
static void Project(ProjLib_Projector& P, Handle(Adaptor3d_HCurve)& C)
{
GeomAbs_CurveType CType = C->GetType();
switch (CType) {
case GeomAbs_Line:
P.Project(C->Line());
break;
case GeomAbs_Circle:
P.Project(C->Circle());
break;
case GeomAbs_Ellipse:
P.Project(C->Ellipse());
break;
case GeomAbs_Hyperbola:
P.Project(C->Hyperbola());
break;
case GeomAbs_Parabola:
P.Project(C->Parabola());
break;
case GeomAbs_BSplineCurve:
case GeomAbs_BezierCurve:
case GeomAbs_OtherCurve: // try the approximation
break;
default:
Standard_NoSuchObject::Raise(" ");
}
}
[/code]

Do I have to implement the call to ProjLib_ComApprox myself now? I cannot believe that I am the first person requiring to project splines onto a plane, so there must be a usable way implemented already...