Material.DrawBegin C# (CSharp) Method

    protected override void DrawBegin()
    {
        int w = ViewportWidth;
        int h = ViewportHeight;

        gl.glViewport(0, 0, w, h);

        gl.glMatrixMode(gl.GL_PROJECTION);
        gl.glLoadIdentity();

        if (w <= (h * 2))
            gl.glOrtho(-6.0, 6.0, -3.0 * ((float)h * 2) / (float)w,
                3.0 * ((float)h * 2) / (float)w, -10.0, 10.0);
        else
            gl.glOrtho(-6.0 * (float)w / ((float)h * 2),
                6.0 * (float)w / ((float)h * 2), -3.0, 3.0, -10.0, 10.0);


        GI.Buffers.ColorBuffer.Clear();
        GI.Buffers.DepthBuffer.Clear();

        GI.ShadeModel(ShadingModel.Smooth);
    }