 <code class="function">glViewport</code> specifies the affine transformation of
            <math overflow="scroll"><mi mathvariant="italic">x</mi></math>
            and
            <math overflow="scroll"><mi mathvariant="italic">y</mi></math>
            from
            normalized device coordinates to window coordinates.
            Let
            <math overflow="scroll">

                <mfenced open="(" close=")">
                    <msub><mi mathvariant="italic">x</mi>
                    <mi ma