Fill space between two curves in cartesian graph

I am having some difficulties for feeling the space between two cu开发者_运维技巧rves in a carthesian graph in my WinForms program.

Basicly I have two curves that I draw them on a bitmap using this method:

    public Bitmap DrawEnvelope(PointF[] u, PointF[] d)
    {
        g = Graphics.FromImage(box);
        g.SmoothingMode = SmoothingMode.AntiAlias;
        g.PixelOffsetMode = PixelOffsetMode.HighQuality;

        Pen pengraph = new Pen(Color.FromArgb(50, 0 ,0 ,200), 1F);
        pengraph.Alignment = PenAlignment.Center;

        g.DrawCurve(pengraph, u, 0); //uperline
        g.DrawCurve(pengraph, d, 0); //downline

        g.Dispose();

        return box;
    }

Now I want to fill the space between these two curves with a color. How can this be done?

I looked in MSDN and found a method like FillClosedCurve. but it does not help me in this case.

Thanks.

Solved by Akh's comment

        joinedCurves.AddRange(u);
        joinedCurves.AddRange(d.Reverse());

        PointF[] fillPoints = joinedCurves.ToArray();
        SolidBrush fillBrush = new SolidBrush(Color.FromArgb(50, 0, 0, 200));
        FillMode newFillMode = FillMode.Alternate;

        g.FillClosedCurve(fillBrush, fillPoints, newFillMode, 0);

List<PointF> joinedCurves = new List<PointF>();
joinedCurves.AddRange(u);        
jointCurves.AddRange(d.Reverse());      
PointF[] fillPoints = joinedCurves.ToArray();    
SolidBrush fillBrush = new SolidBrush(Color.FromArgb(50, 0, 0, 200));    
FillMode newFillMode = FillMode.Alternate;    
g.FillClosedCurve(fillBrush, fillPoints, newFillMode, 0);