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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>·</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>·</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>·</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>·</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> |