>EmitVertex</span></span></a> without having
            written <code class="varname">gl_ClipDistance</code> since the last call to <a class="citerefentry" href="EmitVertex"><span class="citerefentry"><span class="refentrytitle">EmitVertex</span></span></a>
            (or hasn't written it at all).
        </p>
        <p>
            In the tessellation control, tessellation evaluation and geoemetry languages,
            the <code class="varname">gl_PerVertex</code> named block is used to construct an a