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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="glDrawBuffer"> | |
5 | <refmeta> | |
6 | <refmetainfo> | |
7 | <copyright> | |
8 | <year>1991-2006</year> | |
9 | <holder>Silicon Graphics, Inc.</holder> | |
10 | </copyright> | |
11 | </refmetainfo> | |
12 | <refentrytitle>glDrawBuffer</refentrytitle> | |
13 | <manvolnum>3G</manvolnum> | |
14 | </refmeta> | |
15 | <refnamediv> | |
16 | <refname>glDrawBuffer</refname> | |
17 | <refpurpose>specify which color buffers are to be drawn into</refpurpose> | |
18 | </refnamediv> | |
19 | <refsynopsisdiv><title>C Specification</title> | |
20 | <funcsynopsis> | |
21 | <funcprototype> | |
22 | <funcdef>void <function>glDrawBuffer</function></funcdef> | |
23 | <paramdef>GLenum <parameter>mode</parameter></paramdef> | |
24 | </funcprototype> | |
25 | </funcsynopsis> | |
26 | </refsynopsisdiv> | |
27 | <!-- eqn: ignoring delim $$ --> | |
28 | <refsect1 id="parameters"><title>Parameters</title> | |
29 | <variablelist> | |
30 | <varlistentry> | |
31 | <term><parameter>mode</parameter></term> | |
32 | <listitem> | |
33 | <para> | |
34 | Specifies up to four color buffers to be drawn into. | |
35 | Symbolic constants | |
36 | <constant>GL_NONE</constant>, | |
37 | <constant>GL_FRONT_LEFT</constant>, | |
38 | <constant>GL_FRONT_RIGHT</constant>, | |
39 | <constant>GL_BACK_LEFT</constant>, | |
40 | <constant>GL_BACK_RIGHT</constant>, | |
41 | <constant>GL_FRONT</constant>, | |
42 | <constant>GL_BACK</constant>, | |
43 | <constant>GL_LEFT</constant>, | |
44 | <constant>GL_RIGHT</constant>, | |
45 | <constant>GL_FRONT_AND_BACK</constant>, and | |
46 | <constant>GL_AUX</constant><emphasis>i</emphasis>, | |
47 | where <emphasis>i</emphasis> is between 0 and the value of <constant>GL_AUX_BUFFERS</constant> minus 1, | |
48 | are accepted. (<constant>GL_AUX_BUFFERS</constant> is not the upper limit; use <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> | |
49 | to query the number of available aux buffers.) | |
50 | The initial value is <constant>GL_FRONT</constant> for single-buffered contexts, | |
51 | and <constant>GL_BACK</constant> for double-buffered contexts. | |
52 | </para> | |
53 | </listitem> | |
54 | </varlistentry> | |
55 | </variablelist> | |
56 | </refsect1> | |
57 | <refsect1 id="description"><title>Description</title> | |
58 | <para> | |
59 | When colors are written to the frame buffer, | |
60 | they are written into the color buffers specified by <function>glDrawBuffer</function>. | |
61 | The specifications are as follows: | |
62 | </para> | |
63 | <variablelist> | |
64 | <varlistentry> | |
65 | <term><constant>GL_NONE</constant></term> | |
66 | <listitem> | |
67 | <para> | |
68 | No color buffers are written. | |
69 | </para> | |
70 | </listitem> | |
71 | </varlistentry> | |
72 | <varlistentry> | |
73 | <term><constant>GL_FRONT_LEFT</constant></term> | |
74 | <listitem> | |
75 | <para> | |
76 | Only the front left color buffer is written. | |
77 | </para> | |
78 | </listitem> | |
79 | </varlistentry> | |
80 | <varlistentry> | |
81 | <term><constant>GL_FRONT_RIGHT</constant></term> | |
82 | <listitem> | |
83 | <para> | |
84 | Only the front right color buffer is written. | |
85 | </para> | |
86 | </listitem> | |
87 | </varlistentry> | |
88 | <varlistentry> | |
89 | <term><constant>GL_BACK_LEFT</constant></term> | |
90 | <listitem> | |
91 | <para> | |
92 | Only the back left color buffer is written. | |
93 | </para> | |
94 | </listitem> | |
95 | </varlistentry> | |
96 | <varlistentry> | |
97 | <term><constant>GL_BACK_RIGHT</constant></term> | |
98 | <listitem> | |
99 | <para> | |
100 | Only the back right color buffer is written. | |
101 | </para> | |
102 | </listitem> | |
103 | </varlistentry> | |
104 | <varlistentry> | |
105 | <term><constant>GL_FRONT</constant></term> | |
106 | <listitem> | |
107 | <para> | |
108 | Only the front left and front right color buffers are written. | |
109 | If there is no front right color buffer, | |
110 | only the front left color buffer is written. | |
111 | </para> | |
112 | </listitem> | |
113 | </varlistentry> | |
114 | <varlistentry> | |
115 | <term><constant>GL_BACK</constant></term> | |
116 | <listitem> | |
117 | <para> | |
118 | Only the back left and back right color buffers are written. | |
119 | If there is no back right color buffer, | |
120 | only the back left color buffer is written. | |
121 | </para> | |
122 | </listitem> | |
123 | </varlistentry> | |
124 | <varlistentry> | |
125 | <term><constant>GL_LEFT</constant></term> | |
126 | <listitem> | |
127 | <para> | |
128 | Only the front left and back left color buffers are written. | |
129 | If there is no back left color buffer, | |
130 | only the front left color buffer is written. | |
131 | </para> | |
132 | </listitem> | |
133 | </varlistentry> | |
134 | <varlistentry> | |
135 | <term><constant>GL_RIGHT</constant></term> | |
136 | <listitem> | |
137 | <para> | |
138 | Only the front right and back right color buffers are written. | |
139 | If there is no back right color buffer, | |
140 | only the front right color buffer is written. | |
141 | </para> | |
142 | </listitem> | |
143 | </varlistentry> | |
144 | <varlistentry> | |
145 | <term><constant>GL_FRONT_AND_BACK</constant></term> | |
146 | <listitem> | |
147 | <para> | |
148 | All the front and back color buffers | |
149 | (front left, front right, back left, back right) | |
150 | are written. | |
151 | If there are no back color buffers, | |
152 | only the front left and front right color buffers are written. | |
153 | If there are no right color buffers, | |
154 | only the front left and back left color buffers are written. | |
155 | If there are no right or back color buffers, | |
156 | only the front left color buffer is written. | |
157 | </para> | |
158 | </listitem> | |
159 | </varlistentry> | |
160 | <varlistentry> | |
161 | <term><constant>GL_AUX</constant><emphasis>i</emphasis></term> | |
162 | <listitem> | |
163 | <para> | |
164 | Only auxiliary color buffer <emphasis>i</emphasis> is written. | |
165 | </para> | |
166 | </listitem> | |
167 | </varlistentry> | |
168 | </variablelist> | |
169 | <para> | |
170 | If more than one color buffer is selected for drawing, | |
171 | then blending or logical operations are computed and applied independently | |
172 | for each color buffer and can produce different results in each buffer. | |
173 | </para> | |
174 | <para> | |
175 | Monoscopic contexts include only | |
176 | <emphasis>left</emphasis> | |
177 | buffers, and stereoscopic contexts include both | |
178 | <emphasis>left</emphasis> | |
179 | and | |
180 | <emphasis>right</emphasis> | |
181 | buffers. | |
182 | Likewise, single-buffered contexts include only | |
183 | <emphasis>front</emphasis> | |
184 | buffers, and double-buffered contexts include both | |
185 | <emphasis>front</emphasis> | |
186 | and | |
187 | <emphasis>back</emphasis> | |
188 | buffers. | |
189 | The context is selected at GL initialization. | |
190 | </para> | |
191 | </refsect1> | |
192 | <refsect1 id="notes"><title>Notes</title> | |
193 | <para> | |
194 | It is always the case that <constant>GL_AUX</constant> | |
195 | <inlineequation><mml:math><mml:mi mathvariant="italic">i</mml:mi></mml:math></inlineequation> | |
196 | = <constant>GL_AUX0</constant> + | |
197 | <inlineequation><mml:math><mml:mi mathvariant="italic">i</mml:mi></mml:math></inlineequation>. | |
198 | </para> | |
199 | </refsect1> | |
200 | <refsect1 id="errors"><title>Errors</title> | |
201 | <para> | |
202 | <constant>GL_INVALID_ENUM</constant> is generated if <parameter>mode</parameter> is not an accepted value. | |
203 | </para> | |
204 | <para> | |
205 | <constant>GL_INVALID_OPERATION</constant> is generated if none of the buffers indicated | |
206 | by <parameter>mode</parameter> exists. | |
207 | </para> | |
208 | <para> | |
209 | <constant>GL_INVALID_OPERATION</constant> is generated if <function>glDrawBuffer</function> | |
210 | is executed between the execution of <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry> | |
211 | and the corresponding execution of <citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>. | |
212 | </para> | |
213 | </refsect1> | |
214 | <refsect1 id="associatedgets"><title>Associated Gets</title> | |
215 | <para> | |
216 | <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_DRAW_BUFFER</constant> | |
217 | </para> | |
218 | <para> | |
219 | <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_AUX_BUFFERS</constant> | |
220 | </para> | |
221 | </refsect1> | |
222 | <refsect1 id="seealso"><title>See Also</title> | |
223 | <para> | |
224 | <citerefentry><refentrytitle>glBlendFunc</refentrytitle></citerefentry>, | |
225 | <citerefentry><refentrytitle>glColorMask</refentrytitle></citerefentry>, | |
226 | <citerefentry><refentrytitle>glIndexMask</refentrytitle></citerefentry>, | |
227 | <citerefentry><refentrytitle>glLogicOp</refentrytitle></citerefentry>, | |
228 | <citerefentry><refentrytitle>glReadBuffer</refentrytitle></citerefentry> | |
229 | </para> | |
230 | </refsect1> | |
231 | <refsect1 id="Copyright"><title>Copyright</title> | |
232 | <para> | |
233 | Copyright <trademark class="copyright"></trademark> 1991-2006 | |
234 | Silicon Graphics, Inc. This document is licensed under the SGI | |
235 | Free Software B License. For details, see | |
236 | <ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>. | |
237 | </para> | |
238 | </refsect1> | |
239 | </refentry> |