problems with GeomAPI_ProjectOnSurf

Hi,

I use GeomAPI_ProjectOnSurf in a fucntion for generating shape meshes.
But, I meet problems. Sometimes, GeomAPI_ProjectOnSurf is unable to
generate a projected point. For instance, look at the following piece
of program.
#include

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#include

int main()
{
gp_Pnt O(0,0,0);
gp_Dir N(0,0,1);
gp_Dir Vx(1,0,0);
Handle_Geom_Ellipse ellipse = new Geom_Ellipse(gp_Ax2(O,N,Vx),4,2);

BRepBuilderAPI_MakeEdge edge_builder(ellipse, 0,PI/2);
TopoDS_Shape E = edge_builder.Shape();

gp_Ax1 axis(O,Vx);

BRepPrimAPI_MakeRevol mkRev(E,axis, PI/2);
if (!mkRev.IsDone())
exit(0);

gp_Pnt P(2,0,0);
TopoDS_Shape shape = mkRev->Shape();

TopTools_IndexedMapOfShape MS;
TopExp().MapShapes(shape, TopAbs_FACE, MS);

// only one generated face whose corresponding surface type is GeomSurfaceOfRevolution
Handle_Geom_Surface Surf = BRep_Tool().Surface(TopoDS::Face(MS(1)));

GeomAPI_ProjectPointOnSurf Proj(P, Surf);

for (int i = 1; i {
gp_pnt cur = Proj.Point(i);
cout }
}

With the point P(2,0,0), there is no projected point. With other points
like P(0,0,1) or P(0,1,0) there is three points. I don't understqnd why.

Moreover to write my meshing function, I need to be able to project any point without exception.

I hope you could hep me, thanks for advance,

Franck