ate fragments. The z component is the depth value that would be used for the
            fragment's depth if no shader contained any writes to <a class="citerefentry" href="gl_FragDepth"><span class="citerefentry"><span class="refentrytitle">gl_FragDepth</span></span></a>.
        </p>
        <p>
            <code class="varname">gl_FragCoord</code> may be redeclared with the additional layout qualifier identifiers
            <code class="function">origin_upper_left</code> or <code class="function">pixel_