protected override void DrawBegin()
{
base.DrawBegin();
// Reset the coordinate system before modifying
GI.MatrixMode(MatrixMode.Projection);
GI.LoadIdentity();
// Set the clipping volume
GI.Glu.Perspective(35.0f, fAspect, 1.0f, 500.0f);
// Set the viewpoint
GI.MatrixMode(MatrixMode.Modelview);
GI.LoadIdentity();
GI.Translate(fCameraLocation);
GI.Rotate(fCameraRotation);
}