lighting

private void checkBox2_CheckedChanged(object sender, EventArgs e)
        {
            if (checkBox2.Checked)
            {
                if (checkBox1.Checked)
                {
                    GL.Enable(EnableCap.Light1);

                    GL.Light(LightName.Light1, LightParameter.Diffuse, Color.Blue);
                    GL.Light(LightName.Light1, LightParameter.Position, vLight2);
                }
                else
                {
                    GL.Enable(EnableCap.Lighting);
                    GL.Enable(EnableCap.Light1);

                    GL.Light(LightName.Light1, LightParameter.Diffuse, Color.Blue);
                    GL.Light(LightName.Light1, LightParameter.Position, vLight2);
                }
            }
            else
            {
                GL.Disable(EnableCap.Lighting);
                GL.Disable(EnableCap.Light1);
            }

            MainViewport.Invalidate();
        }
 private void trackBar1_Scroll(object sender, EventArgs e)
        {
                blue = Color.FromArgb(0, 0, trackBar1.Value);
            GL.Light(LightName.Light1, LightParameter.Diffuse, blue);
            MainViewport.Invalidate();
        }


//linie
//bool vizLinie= false;

 private void button3_Click(object sender, EventArgs e)
        {
            if (vizLinie==true)
            {
                vizLinie = false;
            }
            else
            {
                vizLinie = true;
            }
            MainViewport.Invalidate();
        }

//IN VIEWPOINT_PAINT

if (vizLinie==true)
            {
                GL.Color3(Color.Aquamarine);
                GL.Begin(PrimitiveType.Lines);
                GL.Vertex4(vLight1);
                GL.Vertex4(vLight2);
                GL.End();
            }