ass="varname">gl_PerVertex</code> named block
            is used to construct an array, <code class="varname">gl_out[]</code>, whose <code class="varname">gl_ClipDistance</code>
            members hold clip distances for each of the control points, which become available as inputs to the subsequent
            tessellation evaluation shader.
        </p>
        <p>
            The value of <code class="varname">gl_ClipDistance</code> (or the <code class="varname">gl_ClipDistance</code> member of the <cod