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<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE html><html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>glDrawBuffers - OpenGL 4 Reference Pages</title>
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<header/>
<div class="refentry" id="glDrawBuffers">
<div class="titlepage"/>
<div class="refnamediv">
<h2>Name</h2>
<p>glDrawBuffers, glNamedFramebufferDrawBuffers — Specifies a list of color buffers to be drawn
into</p>
</div>
<div class="refsynopsisdiv">
<h2>C Specification</h2>
<div class="funcsynopsis">
<table style="border: 0; cellspacing: 0; cellpadding: 0;" class="funcprototype-table">
<tr>
<td>
<code class="funcdef">void <strong class="fsfunc">glDrawBuffers</strong>(</code>
</td>
<td>GLsizei <var class="pdparam">n</var>, </td>
</tr>
<tr>
<td> </td>
<td>const GLenum *<var class="pdparam">bufs</var><code>)</code>;</td>
</tr>
</table>
<div class="funcprototype-spacer"> </div>
<table style="border: 0; cellspacing: 0; cellpadding: 0;" class="funcprototype-table">
<tr>
<td>
<code class="funcdef">void <strong class="fsfunc">glNamedFramebufferDrawBuffers</strong>(</code>
</td>
<td>GLuint <var class="pdparam">framebuffer</var>, </td>
</tr>
<tr>
<td> </td>
<td>GLsizei <var class="pdparam">n</var>, </td>
</tr>
<tr>
<td> </td>
<td>const GLenum *<var class="pdparam">bufs</var><code>)</code>;</td>
</tr>
</table>
<div class="funcprototype-spacer"> </div>
</div>
</div>
<div class="refsect1" id="parameters">
<h2>Parameters</h2>
<div class="variablelist">
<dl class="variablelist">
<dt>
<span class="term">
<em class="parameter">
<code>framebuffer</code>
</em>
</span>
</dt>
<dd>
<p>Specifies the name of the framebuffer object for
<code class="function">glNamedFramebufferDrawBuffers</code>.</p>
</dd>
<dt>
<span class="term">
<em class="parameter">
<code>n</code>
</em>
</span>
</dt>
<dd>
<p>Specifies the number of buffers in
<em class="parameter"><code>bufs</code></em>.</p>
</dd>
<dt>
<span class="term">
<em class="parameter">
<code>bufs</code>
</em>
</span>
</dt>
<dd>
<p>Points to an array of symbolic constants specifying the
buffers into which fragment colors or data values will be
written.</p>
</dd>
</dl>
</div>
</div>
<div class="refsect1" id="description">
<h2>Description</h2>
<p><code class="function">glDrawBuffers</code> and <code class="function">glNamedFramebufferDrawBuffers</code> define an array of buffers into
which outputs from the fragment shader data will be written. If a fragment
shader writes a value to one or more user defined output variables, then
the value of each variable will be written into the buffer specified at a
location within <em class="parameter"><code>bufs</code></em> corresponding to the location
assigned to that user defined output. The draw buffer used for user
defined outputs assigned to locations greater than or equal to
<em class="parameter"><code>n</code></em> is implicitly set to <code class="constant">GL_NONE</code>
and any data written to such an output is discarded.</p>
<p>For <code class="function">glDrawBuffers</code>, the framebuffer object that
is bound to the <code class="constant">GL_DRAW_FRAMEBUFFER</code> binding will be
used. For <code class="function">glNamedFramebufferDrawBuffers</code>,
<em class="parameter"><code>framebuffer</code></em> is the name of the framebuffer object.
If <em class="parameter"><code>framebuffer</code></em> is zero, then the default
framebuffer is affected.</p>
<p>The symbolic constants contained in <em class="parameter"><code>bufs</code></em> may
be any of the following:</p>
<div class="variablelist">
<dl class="variablelist">
<dt>
<span class="term">
<code class="constant">GL_NONE</code>
</span>
</dt>
<dd>
<p>The fragment shader output value is not written into any color
buffer.</p>
</dd>
<dt>
<span class="term">
<code class="constant">GL_FRONT_LEFT</code>
</span>
</dt>
<dd>
<p>The fragment shader output value is written into the front
left color buffer.</p>
</dd>
<dt>
<span class="term">
<code class="constant">GL_FRONT_RIGHT</code>
</span>
</dt>
<dd>
<p>The fragment shader output value is written into the front
right color buffer.</p>
</dd>
<dt>
<span class="term">
<code class="constant">GL_BACK_LEFT</code>
</span>
</dt>
<dd>
<p>The fragment shader output value is written into the back left
color buffer.</p>
</dd>
<dt>
<span class="term">
<code class="constant">GL_BACK_RIGHT</code>
</span>
</dt>
<dd>
<p>The fragment shader output value is written into the back
right color buffer.</p>
</dd>
<dt>
<span class="term">
<code class="constant">GL_COLOR_ATTACHMENT</code>
<span class="emphasis">
<em>n</em>
</span>
</span>
</dt>
<dd>
<p>The fragment shader output value is written into the
<span class="emphasis"><em>n</em></span>th color attachment of the current
framebuffer. <span class="emphasis"><em>n</em></span> may range from zero to the value
of <code class="constant">GL_MAX_COLOR_ATTACHMENTS</code>.</p>
</dd>
</dl>
</div>
<p>Except for <code class="constant">GL_NONE</code>, the preceding symbolic
constants may not appear more than once in <em class="parameter"><code>bufs</code></em>.
The maximum number of draw buffers supported is implementation dependent
and can be queried by calling <a class="citerefentry" href="glGet.xhtml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with the argument
<code class="constant">GL_MAX_DRAW_BUFFERS</code>.</p>
</div>
<div class="refsect1" id="notes">
<h2>Notes</h2>
<p>The symbolic constants <code class="constant">GL_FRONT</code>,
<code class="constant">GL_BACK</code>, <code class="constant">GL_LEFT</code>,
<code class="constant">GL_RIGHT</code>, and <code class="constant">GL_FRONT_AND_BACK</code>
are not allowed in the <em class="parameter"><code>bufs</code></em> array since they may
refer to multiple buffers.</p>
<p>If a fragment shader does not write to a user defined output
variable, the values of the fragment colors following shader execution are
undefined. For each fragment generated in this situation, a different
value may be written into each of the buffers specified by
<em class="parameter"><code>bufs</code></em>.</p>
</div>
<div class="refsect1" id="errors">
<h2>Errors</h2>
<p><code class="constant">GL_INVALID_OPERATION</code> error is generated by
<code class="function">glNamedFramebufferDrawBuffers</code> if
<em class="parameter"><code>framebuffer</code></em> is not zero or the name of an existing
framebuffer object.</p>
<p><code class="constant">GL_INVALID_ENUM</code> is generated if one of the
values in <em class="parameter"><code>bufs</code></em> is not an accepted value.</p>
<p><code class="constant">GL_INVALID_ENUM</code> is generated if the API call
refers to the default framebuffer and one or more of the values in
<em class="parameter"><code>bufs</code></em> is one of the
<code class="constant">GL_COLOR_ATTACHMENT</code><span class="emphasis"><em>n</em></span>
tokens.</p>
<p><code class="constant">GL_INVALID_ENUM</code> is generated if the API call
refers to a framebuffer object and one or more of the values in
<em class="parameter"><code>bufs</code></em> is anything other than
<code class="constant">GL_NONE</code> or one of the
<code class="constant">GL_COLOR_ATTACHMENT</code><span class="emphasis"><em>n</em></span>
tokens.</p>
<p><code class="constant">GL_INVALID_ENUM</code> is generated if
<em class="parameter"><code>n</code></em> is less than 0.</p>
<p><code class="constant">GL_INVALID_OPERATION</code> is generated if a symbolic
constant other than <code class="constant">GL_NONE</code> appears more than once in
<em class="parameter"><code>bufs</code></em>.</p>
<p><code class="constant">GL_INVALID_OPERATION</code> is generated if any of the
entries in <em class="parameter"><code>bufs</code></em> (other than
<code class="constant">GL_NONE</code> ) indicates a color buffer that does not
exist in the current GL context.</p>
<p><code class="constant">GL_INVALID_OPERATION</code> is generated if any value
in <em class="parameter"><code>bufs</code></em> is <code class="constant">GL_BACK</code>, and
<em class="parameter"><code>n</code></em> is not one.</p>
<p><code class="constant">GL_INVALID_VALUE</code> is generated if
<em class="parameter"><code>n</code></em> is greater than
<code class="constant">GL_MAX_DRAW_BUFFERS</code>.</p>
</div>
<div class="refsect1" id="associatedgets">
<h2>Associated Gets</h2>
<p><a class="citerefentry" href="glGet.xhtml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument
<code class="constant">GL_MAX_DRAW_BUFFERS</code></p>
<p><a class="citerefentry" href="glGet.xhtml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument
<code class="constant">GL_DRAW_BUFFER</code><span class="emphasis"><em>i</em></span> where
<span class="emphasis"><em><code class="code">i</code></em></span> indicates the number of the draw
buffer whose value is to be queried</p>
</div>
<div class="refsect1" id="versions">
<h2>Version Support</h2>
<div class="informaltable">
<table style="border-collapse: collapse; border-top: 2px solid ; border-bottom: 2px solid ; border-left: 2px solid ; border-right: 2px solid ; ">
<colgroup>
<col style="text-align: left; "/>
<col style="text-align: center; " class="firstvers"/>
<col style="text-align: center; "/>
<col style="text-align: center; "/>
<col style="text-align: center; "/>
<col style="text-align: center; "/>
<col style="text-align: center; "/>
<col style="text-align: center; "/>
<col style="text-align: center; "/>
<col style="text-align: center; "/>
<col style="text-align: center; "/>
<col style="text-align: center; "/>
<col style="text-align: center; " class="lastvers"/>
</colgroup>
<thead>
<tr>
<th style="text-align: left; border-right: 2px solid ; ">
</th>
<th style="text-align: center; border-bottom: 2px solid ; " colspan="12">
<span class="bold"><strong>OpenGL Version</strong></span>
</th>
</tr>
<tr>
<th style="text-align: left; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>Function / Feature Name</strong></span>
</th>
<th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>2.0</strong></span>
</th>
<th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>2.1</strong></span>
</th>
<th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>3.0</strong></span>
</th>
<th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>3.1</strong></span>
</th>
<th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>3.2</strong></span>
</th>
<th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>3.3</strong></span>
</th>
<th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>4.0</strong></span>
</th>
<th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>4.1</strong></span>
</th>
<th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>4.2</strong></span>
</th>
<th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>4.3</strong></span>
</th>
<th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>4.4</strong></span>
</th>
<th style="text-align: center; border-bottom: 2px solid ; ">
<span class="bold"><strong>4.5</strong></span>
</th>
</tr>
</thead>
<tbody>
<tr>
<td style="text-align: left; border-right: 2px solid ; border-bottom: 2px solid ; ">
<code class="function">glDrawBuffers</code>
</td>
<td style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">✔</td>
<td style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">✔</td>
<td style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">✔</td>
<td style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">✔</td>
<td style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">✔</td>
<td style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">✔</td>
<td style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">✔</td>
<td style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">✔</td>
<td style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">✔</td>
<td style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">✔</td>
<td style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">✔</td>
<td style="text-align: center; border-bottom: 2px solid ; ">✔</td>
</tr>
<tr>
<td style="text-align: left; border-right: 2px solid ; ">
<code class="function">glNamedFramebufferDrawBuffers</code>
</td>
<td style="text-align: center; border-right: 2px solid ; ">-</td>
<td style="text-align: center; border-right: 2px solid ; ">-</td>
<td style="text-align: center; border-right: 2px solid ; ">-</td>
<td style="text-align: center; border-right: 2px solid ; ">-</td>
<td style="text-align: center; border-right: 2px solid ; ">-</td>
<td style="text-align: center; border-right: 2px solid ; ">-</td>
<td style="text-align: center; border-right: 2px solid ; ">-</td>
<td style="text-align: center; border-right: 2px solid ; ">-</td>
<td style="text-align: center; border-right: 2px solid ; ">-</td>
<td style="text-align: center; border-right: 2px solid ; ">-</td>
<td style="text-align: center; border-right: 2px solid ; ">-</td>
<td style="text-align: center; ">✔</td>
</tr>
</tbody>
</table>
</div>
</div>
<div class="refsect1" id="seealso">
<h2>See Also</h2>
<p> <a class="citerefentry" href="glBlendFunc.xhtml"><span class="citerefentry"><span class="refentrytitle">glBlendFunc</span></span></a>,
<a class="citerefentry" href="glColorMask.xhtml"><span class="citerefentry"><span class="refentrytitle">glColorMask</span></span></a>,
<a class="citerefentry" href="glDrawBuffers.xhtml"><span class="citerefentry"><span class="refentrytitle">glDrawBuffers</span></span></a>,
<a class="citerefentry" href="glLogicOp.xhtml"><span class="citerefentry"><span class="refentrytitle">glLogicOp</span></span></a>,
<a class="citerefentry" href="glReadBuffer.xhtml"><span class="citerefentry"><span class="refentrytitle">glReadBuffer</span></span></a></p>
</div>
<div class="refsect1" id="Copyright">
<h2>Copyright</h2>
<p>
Copyright <span class="trademark"/>© 2003-2005 3Dlabs Inc. Ltd.
Copyright <span class="trademark"/>© 2010-2014 Khronos Group.
This material may be distributed subject to the terms and conditions set forth in
the Open Publication License, v 1.0, 8 June 1999.
<a class="link" href="http://opencontent.org/openpub/" target="_top">http://opencontent.org/openpub/</a>.
</p>
</div>
</div>
<footer/>
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