Help needed writing recursive function

Hi :D,
I need help writing a recursive function from an algorithm called "The Diamond-Square Algorithm" @

[http://gameprogrammer.com/fractal.html#diamond]

So far I have this:

Code:

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    Function DiamondSquare(ByVal PointsColl As Point3DCollection) As Point3DCollection

        'Variables

        Dim SquareSize As Integer = Sqrt(PointsColl.Count)

        Dim RandomRange As Integer = 5

        Dim Rand As New Random(1234)


        'Diamond Step

        Dim SqrCorner1 As Integer = 1

        Dim SqrCorner2 As Integer = SquareSize

        Dim SqrCorner3 As Integer = (SquareSize - 1) * SquareSize + 1

        Dim SqrCorner4 As Integer = SquareSize * SquareSize

        Dim SqrCentre As Integer = (SquareSize / 2) ^ 2


        'Assign Diamond Centre value

        Dim SqrCentreValue As Double = PointsColl(SqrCorner1).Y + PointsColl(SqrCorner2).Y + PointsColl(SqrCorner3).Y + PointsColl(SqrCorner4).Y + Rand.Next(0, RandomRange)

        PointsColl(SqrCentre) = New Point3D(PointsColl(SqrCentre).X, SqrCentreValue, PointsColl(SqrCentre).Z)


        'Square Step

        Dim DiamCorner1 As Integer = SquareSize / 2

        Dim DiamCorner2 As Integer = DiamCorner1 + SquareSize

        Dim DiamCorner3 As Integer = DiamCorner2 + SquareSize

        Dim DiamCorner4 As Integer = DiamCorner3 + SquareSize


        'Assign Diamond Centre Values to Diamond Corners

        PointsColl(DiamCorner1) = New Point3D(PointsColl(DiamCorner1).X, SqrCentreValue, PointsColl(DiamCorner1).Z)

        PointsColl(DiamCorner2) = New Point3D(PointsColl(DiamCorner2).X, SqrCentreValue, PointsColl(DiamCorner2).Z)

        PointsColl(DiamCorner3) = New Point3D(PointsColl(DiamCorner3).X, SqrCentreValue, PointsColl(DiamCorner3).Z)

        PointsColl(DiamCorner4) = New Point3D(PointsColl(DiamCorner4).X, SqrCentreValue, PointsColl(DiamCorner4).Z)


        'Split into Four Squares

        Dim Square1 As Point3DCollection '((SquareSize/2)-1)

        Dim Square2 As Point3DCollection '((SquareSize/2)-1)

        Dim Square3 As Point3DCollection '((SquareSize/2)-1)

        Dim Square4 As Point3DCollection '((SquareSize/2)-1)


        'Populate Square 1
        Dim Index As Integer = 0

        For i = 0 To (SquareSize / 2) - 1

            For j = 0 To (SquareSize / 2) - 1

                Square1(Index) = PointsColl((i * SquareSize) + j)

                Index = Index + 1

            Next

        Next

        'Populate Square 2
        Index = 0

        For i = 0 To (SquareSize / 2) - 1

            For j = 0 To (SquareSize / 2) - 1

                Square2(Index) = PointsColl((i * SquareSize) + j + (SquareSize / 2))

                Index = Index + 1

            Next

        Next

        'Populate Square 3
        Index = 0

        For i = 0 To (SquareSize / 2) - 1

            For j = 0 To (SquareSize / 2) - 1

                Square3(Index) = PointsColl(((i + SquareSize / 2) * SquareSize) + j)

                Index = Index + 1

            Next

        Next

        'Populate Square 4
        Index = 0

        For i = 0 To (SquareSize / 2) - 1

            For j = 0 To (SquareSize / 2) - 1

                Square4(Index) = PointsColl(((i + SquareSize / 2) * SquareSize) + j + (SquareSize / 2))

                Index = Index + 1

            Next

        Next


        'Call function for each Quarter Square

        Square1 = DiamondSquare(Square1)

        Square2 = DiamondSquare(Square2)

        Square3 = DiamondSquare(Square3)

        Square4 = DiamondSquare(Square4)


        'Replace Square Values in PointsColl

        'Retrieve Square1

        Index = 0

        For i = 0 To (SquareSize / 2) - 1

            For j = 0 To (SquareSize / 2) - 1

                PointsColl((i * SquareSize) + j) = Square1(Index)

                Index = Index + 1

            Next

        Next


        'Retrieve Square2

        Index = 0

        For i = 0 To (SquareSize / 2) - 1

            For j = 0 To (SquareSize / 2) - 1

                PointsColl((i * SquareSize) + j + (SquareSize / 2)) = Square1(Index)

                Index = Index + 1

            Next

        Next


        'Retrieve Square3

        Index = 0

        For i = 0 To (SquareSize / 2) - 1

            For j = 0 To (SquareSize / 2) - 1

                PointsColl(((i + SquareSize / 2) * SquareSize) + j) = Square1(Index)

                Index = Index + 1

            Next

        Next


        'Retrieve Square4

        Index = 0

        For i = 0 To (SquareSize / 2) - 1

            For j = 0 To (SquareSize / 2) - 1

                PointsColl(((i + SquareSize / 2) * SquareSize) + j + (SquareSize / 2)) = Square1(Index)

                Index = Index + 1

            Next

        Next


    End Function

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What help do you need?

That link has C source code available, are you trying to convert that to VB?

Sorry. I didnt notice that. I cant seem to find a link to the source code.

Found the source - www.math.umd.edu/~asnowden/dmnd-sqr.html

I would like to implement a VB.NET version.

The source on that page is in a zip at http://gameprogrammer.com/fractal/fractal.zip but the link you show above is a better starting point.

I dont know of a converter so I'm afraid its a matter of either converting it line by line manually or looking at the algorithm and starting afresh in .NET. The algorithm seems to be quite well documented so I'd probably plump for coding it from scratch.

I have almost finished it in VB.NET - my attempt is posted above. Im just stuck on the ending.