="emphasis"><em>p4</em></span>, in that order.</p></dd></dl></div></div><div class="refsect1" title="Description"><a id="description"></a><h2>Description</h2><p>Geometry is always clipped against the boundaries of a six-plane
    frustum in x, y, and z. <code class="function">glClipPlane</code> allows the
    specification of additional planes, not necessarily perpendicular to the
    x, y, or z axis, against which all geometry is clipped. To determine the
    maximum number of additional clipping planes, c