Commit | Line | Data |
---|---|---|
7faf1d71 AW |
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="glScissor"> | |
5 | <refmeta> | |
6 | <refmetainfo> | |
7 | <copyright> | |
8 | <year>1991-2006</year> | |
9 | <holder>Silicon Graphics, Inc.</holder> | |
10 | </copyright> | |
11 | </refmetainfo> | |
12 | <refentrytitle>glScissor</refentrytitle> | |
13 | <manvolnum>3G</manvolnum> | |
14 | </refmeta> | |
15 | <refnamediv> | |
16 | <refname>glScissor</refname> | |
17 | <refpurpose>define the scissor box</refpurpose> | |
18 | </refnamediv> | |
19 | <refsynopsisdiv><title>C Specification</title> | |
20 | <funcsynopsis> | |
21 | <funcprototype> | |
22 | <funcdef>void <function>glScissor</function></funcdef> | |
23 | <paramdef>GLint <parameter>x</parameter></paramdef> | |
24 | <paramdef>GLint <parameter>y</parameter></paramdef> | |
25 | <paramdef>GLsizei <parameter>width</parameter></paramdef> | |
26 | <paramdef>GLsizei <parameter>height</parameter></paramdef> | |
27 | </funcprototype> | |
28 | </funcsynopsis> | |
29 | </refsynopsisdiv> | |
30 | <refsect1 id="parameters"><title>Parameters</title> | |
31 | <variablelist> | |
32 | <varlistentry> | |
33 | <term><parameter>x</parameter></term> | |
34 | <term><parameter>y</parameter></term> | |
35 | <listitem> | |
36 | <para> | |
37 | Specify the lower left corner of the scissor box. | |
38 | Initially (0, 0). | |
39 | </para> | |
40 | </listitem> | |
41 | </varlistentry> | |
42 | <varlistentry> | |
43 | <term><parameter>width</parameter></term> | |
44 | <term><parameter>height</parameter></term> | |
45 | <listitem> | |
46 | <para> | |
47 | Specify the width and height of the scissor box. | |
48 | When a GL context is first attached to a window, | |
49 | <parameter>width</parameter> and <parameter>height</parameter> are set to the dimensions of that | |
50 | window. | |
51 | </para> | |
52 | </listitem> | |
53 | </varlistentry> | |
54 | </variablelist> | |
55 | </refsect1> | |
56 | <refsect1 id="description"><title>Description</title> | |
57 | <para> | |
58 | <function>glScissor</function> defines a rectangle, called the scissor box, | |
59 | in window coordinates. | |
60 | The first two arguments, | |
61 | <parameter>x</parameter> and <parameter>y</parameter>, | |
62 | specify the lower left corner of the box. | |
63 | <parameter>width</parameter> and <parameter>height</parameter> specify the width and height of the box. | |
64 | </para> | |
65 | <para> | |
66 | To enable and disable the scissor test, call | |
67 | <citerefentry><refentrytitle>glEnable</refentrytitle></citerefentry> and <citerefentry><refentrytitle>glDisable</refentrytitle></citerefentry> with argument | |
68 | <constant>GL_SCISSOR_TEST</constant>. The test is initially disabled. | |
69 | While the test is enabled, only pixels that lie within the scissor box | |
70 | can be modified by drawing commands. | |
71 | Window coordinates have integer values at the shared corners of | |
72 | frame buffer pixels. | |
73 | <code>glScissor(0,0,1,1)</code> allows modification of only the lower left | |
74 | pixel in the window, and <code>glScissor(0,0,0,0)</code> doesn't allow | |
75 | modification of any pixels in the window. | |
76 | </para> | |
77 | <para> | |
78 | When the scissor test is disabled, | |
79 | it is as though the scissor box includes the entire window. | |
80 | </para> | |
81 | </refsect1> | |
82 | <refsect1 id="errors"><title>Errors</title> | |
83 | <para> | |
84 | <constant>GL_INVALID_VALUE</constant> is generated if either <parameter>width</parameter> or <parameter>height</parameter> is negative. | |
85 | </para> | |
86 | <para> | |
87 | <constant>GL_INVALID_OPERATION</constant> is generated if <function>glScissor</function> | |
88 | is executed between the execution of <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry> | |
89 | and the corresponding execution of <citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>. | |
90 | </para> | |
91 | </refsect1> | |
92 | <refsect1 id="associatedgets"><title>Associated Gets</title> | |
93 | <para> | |
94 | <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_SCISSOR_BOX</constant> | |
95 | </para> | |
96 | <para> | |
97 | <citerefentry><refentrytitle>glIsEnabled</refentrytitle></citerefentry> with argument <constant>GL_SCISSOR_TEST</constant> | |
98 | </para> | |
99 | </refsect1> | |
100 | <refsect1 id="seealso"><title>See Also</title> | |
101 | <para> | |
102 | <citerefentry><refentrytitle>glEnable</refentrytitle></citerefentry>, | |
103 | <citerefentry><refentrytitle>glViewport</refentrytitle></citerefentry> | |
104 | </para> | |
105 | </refsect1> | |
106 | <refsect1 id="Copyright"><title>Copyright</title> | |
107 | <para> | |
108 | Copyright <trademark class="copyright"></trademark> 1991-2006 | |
109 | Silicon Graphics, Inc. This document is licensed under the SGI | |
110 | Free Software B License. For details, see | |
111 | <ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>. | |
112 | </para> | |
113 | </refsect1> | |
114 | </refentry> |