private void glControl_Resize(object sender, EventArgs e)
{
if (!RenderingEnabled) return;
glControl.MakeCurrent();
GL.ClearColor(0.39f, 0.58f, 0.93f, 1.0f);
GL.Viewport(0, 0, glControl.Width, glControl.Height);
GL.PushMatrix();
GL.MatrixMode(MatrixMode.Projection);
GL.LoadIdentity();
SetPerspective();
GL.MatrixMode(MatrixMode.Modelview);
GL.PopMatrix();
}