Public Class C2DMatrix
    Private Structure Matrix
        Public _11, _12, _13 As Double
        Public _21, _22, _23 As Double
        Public _31, _32, _33 As Double
    End Structure

    Dim m_Matrix As Matrix

    Private Sub MatrixMultiply(ByVal mIn As Matrix)
        Dim mat_temp As Matrix

        '//first row
        mat_temp._11 = (m_Matrix._11 * mIn._11) + (m_Matrix._12 * mIn._21) + (m_Matrix._13 * mIn._31)
        mat_temp._12 = (m_Matrix._11 * mIn._12) + (m_Matrix._12 * mIn._22) + (m_Matrix._13 * mIn._32)
        mat_temp._13 = (m_Matrix._11 * mIn._13) + (m_Matrix._12 * mIn._23) + (m_Matrix._13 * mIn._33)

        '//second
        mat_temp._21 = (m_Matrix._21 * mIn._11) + (m_Matrix._22 * mIn._21) + (m_Matrix._23 * mIn._31)
        mat_temp._22 = (m_Matrix._21 * mIn._12) + (m_Matrix._22 * mIn._22) + (m_Matrix._23 * mIn._32)
        mat_temp._23 = (m_Matrix._21 * mIn._13) + (m_Matrix._22 * mIn._23) + (m_Matrix._23 * mIn._33)

        '//third
        mat_temp._31 = (m_Matrix._31 * mIn._11) + (m_Matrix._32 * mIn._21) + (m_Matrix._33 * mIn._31)
        mat_temp._32 = (m_Matrix._31 * mIn._12) + (m_Matrix._32 * mIn._22) + (m_Matrix._33 * mIn._32)
        mat_temp._33 = (m_Matrix._31 * mIn._13) + (m_Matrix._32 * mIn._23) + (m_Matrix._33 * mIn._33)

        m_Matrix = mat_temp
    End Sub

    Public Sub New()
        '//initialize the matrix to an identity matrix
        Identity()
    End Sub

    '//create an identity matrix
    Public Sub Identity()
        m_Matrix._11 = 1
        m_Matrix._12 = 0
        m_Matrix._13 = 0
        m_Matrix._21 = 0
        m_Matrix._22 = 1
        m_Matrix._23 = 0
        m_Matrix._31 = 0
        m_Matrix._32 = 0
        m_Matrix._33 = 1
    End Sub

    '//create a transformation matrix
    Public Sub Translate(ByVal x As Double, ByVal y As Double)
        Dim mat As Matrix

        mat._11 = 1
        mat._12 = 0
        mat._13 = 0
        mat._21 = 0
        mat._22 = 1
        mat._23 = 0
        mat._31 = x
        mat._32 = y
        mat._33 = 1

        '//and multiply
        MatrixMultiply(mat)
    End Sub

    '//create a scale matrix
    Public Sub Scale(ByVal xScale As Double, ByVal yScale As Double)
        Dim mat As Matrix

        mat._11 = xScale
        mat._12 = 0
        mat._13 = 0
        mat._21 = 0
        mat._22 = yScale
        mat._23 = 0
        mat._31 = 0
        mat._32 = 0
        mat._33 = 1
        '//and multiply
        MatrixMultiply(mat)
    End Sub

    '//create a rotation matrix
    Public Sub Rotate(ByVal rot As Double)
        Dim mat As Matrix

        Dim sin As Double = Math.Sin(rot)
        Dim cos = Math.Cos(rot)

        mat._11 = cos
        mat._12 = sin
        mat._13 = 0
        mat._21 = -sin
        mat._22 = cos
        mat._23 = 0
        mat._31 = 0
        mat._32 = 0
        mat._33 = 1
        '//and multiply
        MatrixMultiply(mat)

    End Sub

    '//create a rotation matrix from a fwd and side 2D vector
    Public Sub Rotate(ByVal fwd As Vector2D, ByVal side As Vector2D)
        Dim mat As Matrix

        mat._11 = fwd.x
        mat._12 = fwd.y
        mat._13 = 0
        mat._21 = side.x
        mat._22 = side.y
        mat._23 = 0
        mat._31 = 0
        mat._32 = 0
        mat._33 = 1

        '  //and multiply
        MatrixMultiply(mat)
    End Sub

    '//applys a transformation matrix to a std::vector of points
    Public Sub TransformVector2Ds(ByVal vPoint As ArrayList)
        Dim i As Integer
        For i = 0 To vPoint.Count - 1
            Dim tempX As Double = (m_Matrix._11 * CType(vPoint(i), Vector2D).x) + (m_Matrix._21 * CType(vPoint(i), Vector2D).y) + (m_Matrix._31)
            Dim tempY As Double = (m_Matrix._12 * CType(vPoint(i), Vector2D).x) + (m_Matrix._22 * CType(vPoint(i), Vector2D).y) + (m_Matrix._32)

            CType(vPoint(i), Vector2D).x = tempX
            CType(vPoint(i), Vector2D).y = tempY
        Next
    End Sub

    '//applys a transformation matrix to a point
    Public Sub TransformVector2Ds(ByVal vPoint As Vector2D)
        Dim tempX As Double = (m_Matrix._11 * vPoint.x) + (m_Matrix._21 * vPoint.y) + (m_Matrix._31)
        Dim tempY As Double = (m_Matrix._12 * vPoint.x) + (m_Matrix._22 * vPoint.y) + (m_Matrix._32)

        vPoint.x = tempX
        vPoint.y = tempY
    End Sub

    '//accessors to the matrix elements
    Public Sub _11(ByVal val As Double)
        m_Matrix._11 = val
    End Sub

    Public Sub _12(ByVal val As Double)
        m_Matrix._12 = val
    End Sub

    Public Sub _13(ByVal val As Double)
        m_Matrix._13 = val
    End Sub

    Public Sub _21(ByVal val As Double)
        m_Matrix._21 = val
    End Sub

    Public Sub _22(ByVal val As Double)
        m_Matrix._22 = val
    End Sub

    Public Sub _23(ByVal val As Double)
        m_Matrix._23 = val
    End Sub

    Public Sub _31(ByVal val As Double)
        m_Matrix._31 = val
    End Sub

    Public Sub _32(ByVal val As Double)
        m_Matrix._32 = val
    End Sub

    Public Sub _33(ByVal val As Double)
        m_Matrix._33 = val
    End Sub

End Class