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">
9 <holder>Silicon Graphics, Inc.
</holder>
12 <refentrytitle>glPixelZoom
</refentrytitle>
13 <manvolnum>3G
</manvolnum>
16 <refname>glPixelZoom
</refname>
17 <refpurpose>specify the pixel zoom factors
</refpurpose>
19 <refsynopsisdiv><title>C Specification
</title>
22 <funcdef>void
<function>glPixelZoom
</function></funcdef>
23 <paramdef>GLfloat
<parameter>xfactor
</parameter></paramdef>
24 <paramdef>GLfloat
<parameter>yfactor
</parameter></paramdef>
28 <!-- eqn: ignoring delim $$ -->
29 <refsect1 id=
"parameters"><title>Parameters
</title>
32 <term><parameter>xfactor
</parameter></term>
33 <term><parameter>yfactor
</parameter></term>
37 <inlineequation><mml:math><mml:mi mathvariant=
"italic">x
</mml:mi></mml:math></inlineequation>
39 <inlineequation><mml:math><mml:mi mathvariant=
"italic">y
</mml:mi></mml:math></inlineequation>
40 zoom factors for pixel write operations.
46 <refsect1 id=
"description"><title>Description
</title>
48 <function>glPixelZoom
</function> specifies values for the
49 <inlineequation><mml:math><mml:mi mathvariant=
"italic">x
</mml:mi></mml:math></inlineequation>
51 <inlineequation><mml:math><mml:mi mathvariant=
"italic">y
</mml:mi></mml:math></inlineequation>
53 During the execution of
<citerefentry><refentrytitle>glDrawPixels
</refentrytitle></citerefentry> or
<citerefentry><refentrytitle>glCopyPixels
</refentrytitle></citerefentry>,
55 (
<inlineequation><mml:math>
57 <mml:mi mathvariant=
"italic">xr
</mml:mi>
58 </mml:math></inlineequation>,
59 <inlineequation><mml:math>
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
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
72 (
<inlineequation><mml:math>
73 <!-- eqn: xr + n cdot xfactor:-->
75 <mml:mi mathvariant=
"italic">xr
</mml:mi>
78 <mml:mi mathvariant=
"italic">n
</mml:mi>
79 <mml:mo>·</mml:mo>
80 <mml:mi mathvariant=
"italic">xfactor
</mml:mi>
83 </mml:math></inlineequation>,
84 <inlineequation><mml:math>
85 <!-- eqn: yr + m cdot yfactor:-->
87 <mml:mi mathvariant=
"italic">yr
</mml:mi>
90 <mml:mi mathvariant=
"italic">m
</mml:mi>
91 <mml:mo>·</mml:mo>
92 <mml:mi mathvariant=
"italic">yfactor
</mml:mi>
95 </mml:math></inlineequation>)
98 (
<inlineequation><mml:math>
99 <!-- eqn: xr + (n+1) cdot xfactor:-->
101 <mml:mi mathvariant=
"italic">xr
</mml:mi>
104 <mml:mfenced open=
"(" close=
")">
106 <mml:mi mathvariant=
"italic">n
</mml:mi>
111 <mml:mo>·</mml:mo>
112 <mml:mi mathvariant=
"italic">xfactor
</mml:mi>
115 </mml:math></inlineequation>,
116 <inlineequation><mml:math>
117 <!-- eqn: yr + (m+1) cdot yfactor:-->
119 <mml:mi mathvariant=
"italic">yr
</mml:mi>
122 <mml:mfenced open=
"(" close=
")">
124 <mml:mi mathvariant=
"italic">m
</mml:mi>
129 <mml:mo>·</mml:mo>
130 <mml:mi mathvariant=
"italic">yfactor
</mml:mi>
133 </mml:math></inlineequation>)
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.
141 Pixel zoom factors are not limited to positive values.
142 Negative zoom factors reflect the resulting image about the current
146 <refsect1 id=
"errors"><title>Errors
</title>
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>.
153 <refsect1 id=
"associatedgets"><title>Associated Gets
</title>
155 <citerefentry><refentrytitle>glGet
</refentrytitle></citerefentry> with argument
<constant>GL_ZOOM_X
</constant>
158 <citerefentry><refentrytitle>glGet
</refentrytitle></citerefentry> with argument
<constant>GL_ZOOM_Y
</constant>
161 <refsect1 id=
"seealso"><title>See Also
</title>
163 <citerefentry><refentrytitle>glCopyPixels
</refentrytitle></citerefentry>,
164 <citerefentry><refentrytitle>glDrawPixels
</refentrytitle></citerefentry>
167 <refsect1 id=
"Copyright"><title>Copyright
</title>
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>.