From: Colin O Connor

                
Public Function IsLazerHitting(ByVal device As Device, ByVal x As Single, ByVal y As Single) As Boolean
        Dim Near As New Vector3(x, y, 0)
        Dim Far As New Vector3(x, y, 1)
        Near.Unproject(device.Viewport, device.Transform.Projection, device.Transform.View, device.Transform.World)
        Far.Unproject(device.Viewport, device.Transform.Projection, device.Transform.View, device.Transform.World)
        Far.Subtract(Near)
        Dim Closest As New IntersectInformation 'Stores intersection information.

        'Check for intersection.
        If objMainBoxMesh.MeshObject.Intersect(Near, Far, Closest) = True Then
            Return True
        Else
            Return False
        End If
        Return False
End Function

'USAGE^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Private Sub frmMain_MouseDown(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles MyBase.MouseDown
        Select Case e.Button
            Case MouseButtons.Left

        If IsLazerHitting(mobjDX9, e.X, e.Y) = True Then
                    MsgBox("Hit!")
                Else
                    MsgBox("Miss...")
                    End If
        End Select
End Sub