upstream-doc/man2/glPixelZoom.xml

   1 <?xml version="1.0" encoding="UTF-8"?>
   2 <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN"
   3               "http://www.oasis-open.org/docbook/xml/mathml/1.1CR1/dbmathml.dtd">
   4 <refentry id="glPixelZoom">
   5     <refmeta>
   6         <refmetainfo>
   7             <copyright>
   8                 <year>1991-2006</year>
   9                 <holder>Silicon Graphics, Inc.</holder>
  10             </copyright>
  11         </refmetainfo>
  12         <refentrytitle>glPixelZoom</refentrytitle>
  13         <manvolnum>3G</manvolnum>
  14     </refmeta>
  15     <refnamediv>
  16         <refname>glPixelZoom</refname>
  17         <refpurpose>specify the pixel zoom factors</refpurpose>
  18     </refnamediv>
  19     <refsynopsisdiv><title>C Specification</title>
  20         <funcsynopsis>
  21             <funcprototype>
  22                 <funcdef>void <function>glPixelZoom</function></funcdef>
  23                 <paramdef>GLfloat <parameter>xfactor</parameter></paramdef>
  24                 <paramdef>GLfloat <parameter>yfactor</parameter></paramdef>
  25             </funcprototype>
  26         </funcsynopsis>
  27     </refsynopsisdiv>
  28     <!-- eqn: ignoring delim $$ -->
  29     <refsect1 id="parameters"><title>Parameters</title>
  30         <variablelist>
  31         <varlistentry>
  32             <term><parameter>xfactor</parameter></term>
  33             <term><parameter>yfactor</parameter></term>
  34             <listitem>
  35                 <para>
  36                     Specify the
  37                     <inlineequation><mml:math><mml:mi mathvariant="italic">x</mml:mi></mml:math></inlineequation>
  38                     and
  39                     <inlineequation><mml:math><mml:mi mathvariant="italic">y</mml:mi></mml:math></inlineequation>
  40                     zoom factors for pixel write operations.
  41                 </para>
  42             </listitem>
  43         </varlistentry>
  44         </variablelist>
  45     </refsect1>
  46     <refsect1 id="description"><title>Description</title>
  47         <para>
  48             <function>glPixelZoom</function> specifies values for the
  49             <inlineequation><mml:math><mml:mi mathvariant="italic">x</mml:mi></mml:math></inlineequation>
  50             and
  51             <inlineequation><mml:math><mml:mi mathvariant="italic">y</mml:mi></mml:math></inlineequation>
  52             zoom factors.
  53             During the execution of <citerefentry><refentrytitle>glDrawPixels</refentrytitle></citerefentry> or <citerefentry><refentrytitle>glCopyPixels</refentrytitle></citerefentry>,
  54             if
  55             (<inlineequation><mml:math>
  56                 <!-- eqn: xr:-->
  57                 <mml:mi mathvariant="italic">xr</mml:mi>
  58             </mml:math></inlineequation>,
  59             <inlineequation><mml:math>
  60                 <!-- eqn: yr:-->
  61                 <mml:mi mathvariant="italic">yr</mml:mi>
  62             </mml:math></inlineequation>)
  63             is the current raster position,
  64             and a given element is in the
  65             <inlineequation><mml:math><mml:mi mathvariant="italic">m</mml:mi></mml:math></inlineequation>th
  66             row and
  67             <inlineequation><mml:math><mml:mi mathvariant="italic">n</mml:mi></mml:math></inlineequation>th
  68             column of the pixel rectangle,
  69             then pixels whose centers are in the rectangle with corners at
  70         </para>
  71         <para>
  72             (<inlineequation><mml:math>
  73                 <!-- eqn: xr  +  n cdot xfactor:-->
  74                 <mml:mrow>
  75                     <mml:mi mathvariant="italic">xr</mml:mi>
  76                     <mml:mo>+</mml:mo>
  77                     <mml:mrow>
  78                         <mml:mi mathvariant="italic">n</mml:mi>
  79                         <mml:mo>&CenterDot;</mml:mo>
  80                         <mml:mi mathvariant="italic">xfactor</mml:mi>
  81                     </mml:mrow>
  82                 </mml:mrow>
  83             </mml:math></inlineequation>,
  84             <inlineequation><mml:math>
  85                 <!-- eqn: yr  +  m cdot yfactor:-->
  86                 <mml:mrow>
  87                     <mml:mi mathvariant="italic">yr</mml:mi>
  88                     <mml:mo>+</mml:mo>
  89                     <mml:mrow>
  90                         <mml:mi mathvariant="italic">m</mml:mi>
  91                         <mml:mo>&CenterDot;</mml:mo>
  92                         <mml:mi mathvariant="italic">yfactor</mml:mi>
  93                     </mml:mrow>
  94                 </mml:mrow>
  95             </mml:math></inlineequation>)
  96         </para>
  97         <para>
  98             (<inlineequation><mml:math>
  99                 <!-- eqn: xr  +  (n+1) cdot xfactor:-->
 100                 <mml:mrow>
 101                     <mml:mi mathvariant="italic">xr</mml:mi>
 102                     <mml:mo>+</mml:mo>
 103                     <mml:mrow>
 104                         <mml:mfenced open="(" close=")">
 105                             <mml:mrow>
 106                                 <mml:mi mathvariant="italic">n</mml:mi>
 107                                 <mml:mo>+</mml:mo>
 108                                 <mml:mn>1</mml:mn>
 109                             </mml:mrow>
 110                         </mml:mfenced>
 111                         <mml:mo>&CenterDot;</mml:mo>
 112                         <mml:mi mathvariant="italic">xfactor</mml:mi>
 113                     </mml:mrow>
 114                 </mml:mrow>
 115             </mml:math></inlineequation>,
 116             <inlineequation><mml:math>
 117                 <!-- eqn: yr  +  (m+1) cdot yfactor:-->
 118                 <mml:mrow>
 119                     <mml:mi mathvariant="italic">yr</mml:mi>
 120                     <mml:mo>+</mml:mo>
 121                     <mml:mrow>
 122                         <mml:mfenced open="(" close=")">
 123                             <mml:mrow>
 124                                 <mml:mi mathvariant="italic">m</mml:mi>
 125                                 <mml:mo>+</mml:mo>
 126                                 <mml:mn>1</mml:mn>
 127                             </mml:mrow>
 128                         </mml:mfenced>
 129                         <mml:mo>&CenterDot;</mml:mo>
 130                         <mml:mi mathvariant="italic">yfactor</mml:mi>
 131                     </mml:mrow>
 132                 </mml:mrow>
 133             </mml:math></inlineequation>)
 134         </para>
 135         <para>
 136             are candidates for replacement.
 137             Any pixel whose center lies on the bottom or left edge of this rectangular
 138             region is also modified.
 139         </para>
 140         <para>
 141             Pixel zoom factors are not limited to positive values.
 142             Negative zoom factors reflect the resulting image about the current
 143             raster position.
 144         </para>
 145     </refsect1>
 146     <refsect1 id="errors"><title>Errors</title>
 147         <para>
 148             <constant>GL_INVALID_OPERATION</constant> is generated if <function>glPixelZoom</function>
 149             is executed between the execution of <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry>
 150             and the corresponding execution of <citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>.
 151         </para>
 152     </refsect1>
 153     <refsect1 id="associatedgets"><title>Associated Gets</title>
 154         <para>
 155             <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_ZOOM_X</constant>
 156         </para>
 157         <para>
 158             <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_ZOOM_Y</constant>
 159         </para>
 160     </refsect1>
 161     <refsect1 id="seealso"><title>See Also</title>
 162         <para>
 163             <citerefentry><refentrytitle>glCopyPixels</refentrytitle></citerefentry>,
 164             <citerefentry><refentrytitle>glDrawPixels</refentrytitle></citerefentry>
 165         </para>
 166     </refsect1>
 167     <refsect1 id="Copyright"><title>Copyright</title>
 168         <para>
 169             Copyright <trademark class="copyright"></trademark> 1991-2006
 170             Silicon Graphics, Inc. This document is licensed under the SGI
 171             Free Software B License. For details, see
 172             <ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>.
 173         </para>
 174     </refsect1>
 175 </refentry>