/a> is issued and counting vertices and
            primitives from 1, the GL gives each flat-shaded line segment
            <math overflow="scroll"><mi mathvariant="italic">i</mi></math>
            the
            computed color of vertex
            <math overflow="scroll">

                <mrow>
                    <mi mathvariant="italic">i</mi>
                    <mo>+</mo>
                    <mn>1</mn>
                </mrow>
            </math>,
            its second vertex.
            Countin