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<?xml-stylesheet type="text/xsl" href="mathml.xsl"?><html xmlns="http://www.w3.org/1999/xhtml" xmlns:pref="http://www.w3.org/2002/Math/preference" pref:renderer="mathplayer-dl"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>glPixelZoom</title><meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /></head><body><div class="refentry" lang="en" xml:lang="en"><a id="glPixelZoom"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glPixelZoom — specify the pixel zoom factors</p></div><div class="refsynopsisdiv"><h2>C Specification</h2><div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0"><tr><td><code class="funcdef">void <b class="fsfunc">glPixelZoom</b>(</code></td><td>GLfloat  </td><td><var class="pdparam">xfactor</var>, </td></tr><tr><td> </td><td>GLfloat  </td><td><var class="pdparam">yfactor</var><code>)</code>;</td></tr></table></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="parameters"></a><h2>Parameters</h2><div class="variablelist"><dl><dt><span class="term"><em class="parameter"><code>xfactor</code></em>, </span><span class="term"><em class="parameter"><code>yfactor</code></em></span></dt><dd><p>
                    Specify the 
                    <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">x</mml:mi></mml:math>
                    and 
                    <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">y</mml:mi></mml:math>
                    zoom factors for pixel write operations.
                </p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p>
            <code class="function">glPixelZoom</code> specifies values for the 
            <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">x</mml:mi></mml:math>
            and 
            <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">y</mml:mi></mml:math>
            zoom factors.
            During the execution of <a class="citerefentry" href="glDrawPixels.xml"><span class="citerefentry"><span class="refentrytitle">glDrawPixels</span></span></a> or <a class="citerefentry" href="glCopyPixels.xml"><span class="citerefentry"><span class="refentrytitle">glCopyPixels</span></span></a>,
            if 
            (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                
                <mml:mi mathvariant="italic">xr</mml:mi>
            </mml:math>, 
            <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                
                <mml:mi mathvariant="italic">yr</mml:mi>
            </mml:math>)
            is the current raster position,
            and a given element is in the 
            <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">m</mml:mi></mml:math>th
            row and 
            <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">n</mml:mi></mml:math>th
            column of the pixel rectangle,
            then pixels whose centers are in the rectangle with corners at
        </p><p>
            (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                
                <mml:mrow>
                    <mml:mi mathvariant="italic">xr</mml:mi>
                    <mml:mo>+</mml:mo>
                    <mml:mrow>
                        <mml:mi mathvariant="italic">n</mml:mi>
                        <mml:mo>·</mml:mo>
                        <mml:mi mathvariant="italic">xfactor</mml:mi>
                    </mml:mrow>
                </mml:mrow>
            </mml:math>, 
            <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                
                <mml:mrow>
                    <mml:mi mathvariant="italic">yr</mml:mi>
                    <mml:mo>+</mml:mo>
                    <mml:mrow>
                        <mml:mi mathvariant="italic">m</mml:mi>
                        <mml:mo>·</mml:mo>
                        <mml:mi mathvariant="italic">yfactor</mml:mi>
                    </mml:mrow>
                </mml:mrow>
            </mml:math>)
        </p><p>
            (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                
                <mml:mrow>
                    <mml:mi mathvariant="italic">xr</mml:mi>
                    <mml:mo>+</mml:mo>
                    <mml:mrow>
                        <mml:mfenced open="(" close=")">
                            <mml:mrow>
                                <mml:mi mathvariant="italic">n</mml:mi>
                                <mml:mo>+</mml:mo>
                                <mml:mn>1</mml:mn>
                            </mml:mrow>
                        </mml:mfenced>
                        <mml:mo>·</mml:mo>
                        <mml:mi mathvariant="italic">xfactor</mml:mi>
                    </mml:mrow>
                </mml:mrow>
            </mml:math>, 
            <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                
                <mml:mrow>
                    <mml:mi mathvariant="italic">yr</mml:mi>
                    <mml:mo>+</mml:mo>
                    <mml:mrow>
                        <mml:mfenced open="(" close=")">
                            <mml:mrow>
                                <mml:mi mathvariant="italic">m</mml:mi>
                                <mml:mo>+</mml:mo>
                                <mml:mn>1</mml:mn>
                            </mml:mrow>
                        </mml:mfenced>
                        <mml:mo>·</mml:mo>
                        <mml:mi mathvariant="italic">yfactor</mml:mi>
                    </mml:mrow>
                </mml:mrow>
            </mml:math>)
        </p><p>
            are candidates for replacement.
            Any pixel whose center lies on the bottom or left edge of this rectangular
            region is also modified.
        </p><p>
            Pixel zoom factors are not limited to positive values.
            Negative zoom factors reflect the resulting image about the current
            raster position.
        </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="errors"></a><h2>Errors</h2><p>
            <code class="constant">GL_INVALID_OPERATION</code> is generated if <code class="function">glPixelZoom</code>
            is executed between the execution of <a class="citerefentry" href="glBegin.xml"><span class="citerefentry"><span class="refentrytitle">glBegin</span></span></a>
            and the corresponding execution of <a class="citerefentry" href="glEnd.xml"><span class="citerefentry"><span class="refentrytitle">glEnd</span></span></a>.
        </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="associatedgets"></a><h2>Associated Gets</h2><p>
            <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_ZOOM_X</code>
        </p><p>
            <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_ZOOM_Y</code>
        </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p>
            <a class="citerefentry" href="glCopyPixels.xml"><span class="citerefentry"><span class="refentrytitle">glCopyPixels</span></span></a>,
            <a class="citerefentry" href="glDrawPixels.xml"><span class="citerefentry"><span class="refentrytitle">glDrawPixels</span></span></a>
        </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="Copyright"></a><h2>Copyright</h2><p>
            Copyright <span class="trademark"></span>© 1991-2006
            Silicon Graphics, Inc. This document is licensed under the SGI
            Free Software B License. For details, see
            <a class="ulink" href="http://oss.sgi.com/projects/FreeB/" target="_top">http://oss.sgi.com/projects/FreeB/</a>.
        </p></div></div></body></html>
