 of the material. All three light source contributions are
        attenuated equally based on the distance from the vertex to the
        light source and on light source direction, spread exponent,
        and spread cutoff angle. All dot products are replaced with 0
        if they evaluate to a negative value.</p><p>The alpha component of the resulting lighted color is set
        to the alpha value of the material diffuse reflectance.</p></div><div class="refsect1" title="Errors"><a id="errors"></a><h2