HCoop / clinton / guile-figl.git / blame
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1 | <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "xhtml1-transitional.dtd"> |
| 2 | <!-- saved from url=(0013)about:internet --> | |
| 3 | <?xml-stylesheet type="text/xsl" href="mathml.xsl"?><html xmlns="http://www.w3.org/1999/xhtml" xmlns:pref="http://www.w3.org/2002/Math/preference" pref:renderer="mathplayer-dl"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>glDrawBuffers</title><meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /></head><body><div class="refentry" lang="en" xml:lang="en"><a id="glDrawBuffers"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glDrawBuffers — Specifies a list of color buffers to be drawn into</p></div><div class="refsynopsisdiv"><h2>C Specification</h2><div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0"><tr><td><code class="funcdef">void <b class="fsfunc">glDrawBuffers</b>(</code></td><td>GLsizei </td><td><var class="pdparam">n</var>, </td></tr><tr><td> </td><td>const GLenum * </td><td><var class="pdparam">bufs</var><code>)</code>;</td></tr></table></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="parameters"></a><h2>Parameters</h2><div class="variablelist"><dl><dt><span class="term"><em class="parameter"><code>n</code></em></span></dt><dd><p>Specifies the number of buffers in | |
| 4 | <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 | |
| 5 | specifying the buffers into which fragment colors or | |
| 6 | data values will be written.</p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p><code class="function">glDrawBuffers</code> defines an array of | |
| 7 | buffers into which fragment color values or fragment data will | |
| 8 | be written. If no fragment shader is active, rendering | |
| 9 | operations will generate only one fragment color per fragment | |
| 10 | and it will be written into each of the buffers specified by | |
| 11 | <em class="parameter"><code>bufs</code></em>. If a fragment shader is active and | |
| 12 | it writes a value to the output variable | |
| 13 | <code class="code">gl_FragColor</code>, then that value will be | |
| 14 | written into each of the buffers specified by | |
| 15 | <em class="parameter"><code>bufs</code></em>. If a fragment shader is active and | |
| 16 | it writes a value to one or more elements of the output array | |
| 17 | variable <code class="code">gl_FragData[]</code>, then the value of | |
| 18 | <code class="code">gl_FragData[0] </code> will be written into the | |
| 19 | first buffer specified by <em class="parameter"><code>bufs</code></em>, the value | |
| 20 | of <code class="code">gl_FragData[1] </code> will be written into the | |
| 21 | second buffer specified by <em class="parameter"><code>bufs</code></em>, and so | |
| 22 | on up to <code class="code">gl_FragData[n-1]</code>. The draw buffer | |
| 23 | used for <code class="code">gl_FragData[n]</code> and beyond is | |
| 24 | implicitly set to be <code class="constant">GL_NONE</code>.</p><p>The symbolic constants contained in | |
| 25 | <em class="parameter"><code>bufs</code></em> may be any of the following:</p><div class="variablelist"><dl><dt><span class="term"><code class="constant">GL_NONE</code></span></dt><dd><p>The fragment color/data value is not written into | |
| 26 | any color buffer.</p></dd><dt><span class="term"><code class="constant">GL_FRONT_LEFT</code></span></dt><dd><p>The fragment color/data value is written into the | |
| 27 | front left color buffer.</p></dd><dt><span class="term"><code class="constant">GL_FRONT_RIGHT</code></span></dt><dd><p>The fragment color/data value is written into the | |
| 28 | front right color buffer.</p></dd><dt><span class="term"><code class="constant">GL_BACK_LEFT</code></span></dt><dd><p>The fragment color/data value is written into the | |
| 29 | back left color buffer.</p></dd><dt><span class="term"><code class="constant">GL_BACK_RIGHT</code></span></dt><dd><p>The fragment color/data value is written into the | |
| 30 | back right color buffer.</p></dd><dt><span class="term"><code class="constant">GL_AUXi</code></span></dt><dd><p>The fragment color/data value is written into | |
| 31 | auxiliary buffer <code class="code">i</code>.</p></dd></dl></div><p>Except for <code class="constant">GL_NONE</code>, the preceding | |
| 32 | symbolic constants may not appear more than once in | |
| 33 | <em class="parameter"><code>bufs</code></em>. The maximum number of draw buffers | |
| 34 | supported is implementation dependent and can be queried by | |
| 35 | calling | |
| 36 | <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> | |
| 37 | with the argument <code class="constant">GL_MAX_DRAW_BUFFERS</code>. The | |
| 38 | number of auxiliary buffers can be queried by calling | |
| 39 | <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> | |
| 40 | with the argument <code class="constant">GL_AUX_BUFFERS</code>.</p></div><div class="refsect1" lang="en" xml:lang="en"><a id="notes"></a><h2>Notes</h2><p><code class="function">glDrawBuffers</code> is available only if | |
| 41 | the GL version is 2.0 or greater.</p><p>It is always the case that <code class="constant">GL_AUXi</code> = | |
| 42 | <code class="constant">GL_AUX0</code> + <code class="code">i</code>.</p><p>The symbolic constants <code class="constant">GL_FRONT</code>, | |
| 43 | <code class="constant">GL_BACK</code>, <code class="constant">GL_LEFT</code>, | |
| 44 | <code class="constant">GL_RIGHT</code>, and | |
| 45 | <code class="constant">GL_FRONT_AND_BACK</code> are not allowed in the | |
| 46 | <em class="parameter"><code>bufs</code></em> array since they may refer to | |
| 47 | multiple buffers.</p><p>If a fragment shader writes to neither | |
| 48 | <code class="code">gl_FragColor</code> nor | |
| 49 | <code class="code">gl_FragData</code>, the values of the fragment | |
| 50 | colors following shader execution are undefined. For each | |
| 51 | fragment generated in this situation, a different value may be | |
| 52 | written into each of the buffers specified by | |
| 53 | <em class="parameter"><code>bufs</code></em>.</p></div><div class="refsect1" lang="en" xml:lang="en"><a id="errors"></a><h2>Errors</h2><p><code class="constant">GL_INVALID_ENUM</code> is generated if one of the | |
| 54 | values in <em class="parameter"><code>bufs</code></em> is not an accepted | |
| 55 | value.</p><p><code class="constant">GL_INVALID_ENUM</code> is generated if | |
| 56 | <em class="parameter"><code>n</code></em> is less than 0.</p><p><code class="constant">GL_INVALID_OPERATION</code> is generated if a | |
| 57 | symbolic constant other than <code class="constant">GL_NONE</code> | |
| 58 | 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 | |
| 59 | the entries in <em class="parameter"><code>bufs</code></em> (other than | |
| 60 | <code class="constant">GL_NONE</code> ) indicates a color buffer that | |
| 61 | does not exist in the current GL context.</p><p><code class="constant">GL_INVALID_VALUE</code> is generated if | |
| 62 | <em class="parameter"><code>n</code></em> is greater than | |
| 63 | <code class="constant">GL_MAX_DRAW_BUFFERS</code>.</p><p><code class="constant">GL_INVALID_OPERATION</code> is generated if | |
| 64 | <code class="function">glDrawBuffers</code> is executed between the | |
| 65 | execution of | |
| 66 | <a class="citerefentry" href="glBegin.xml"><span class="citerefentry"><span class="refentrytitle">glBegin</span></span></a> | |
| 67 | and the corresponding execution of | |
| 68 | <a class="citerefentry" href="glEnd.xml"><span class="citerefentry"><span class="refentrytitle">glEnd</span></span></a>.</p></div><div class="refsect1" lang="en" xml:lang="en"><a id="associatedgets"></a><h2>Associated Gets</h2><p><a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> | |
| 69 | with argument <code class="constant">GL_MAX_DRAW_BUFFERS</code></p><p><a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> | |
| 70 | with argument <code class="constant">GL_DRAW_BUFFERSi</code> where | |
| 71 | <code class="code">i</code> indicates the number of the draw buffer | |
| 72 | whose value is to be queried</p></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p> <a class="citerefentry" href="glBlendFunc.xml"><span class="citerefentry"><span class="refentrytitle">glBlendFunc</span></span></a>, | |
| 73 | <a class="citerefentry" href="glColorMask.xml"><span class="citerefentry"><span class="refentrytitle">glColorMask</span></span></a>, | |
| 74 | <a class="citerefentry" href="glDrawBuffers.xml"><span class="citerefentry"><span class="refentrytitle">glDrawBuffers</span></span></a>, | |
| 75 | <a class="citerefentry" href="glIndexMask.xml"><span class="citerefentry"><span class="refentrytitle">glIndexMask</span></span></a>, | |
| 76 | <a class="citerefentry" href="glLogicOp.xml"><span class="citerefentry"><span class="refentrytitle">glLogicOp</span></span></a>, | |
| 77 | <a class="citerefentry" href="glReadBuffer.xml"><span class="citerefentry"><span class="refentrytitle">glReadBuffer</span></span></a></p></div><div class="refsect1" lang="en" xml:lang="en"><a id="Copyright"></a><h2>Copyright</h2><p> | |
| 78 | Copyright <span class="trademark"></span>© 2003-2005 3Dlabs Inc. Ltd. | |
| 79 | This material may be distributed subject to the terms and conditions set forth in | |
| 80 | the Open Publication License, v 1.0, 8 June 1999. | |
| 81 | <a class="ulink" href="http://opencontent.org/openpub/" target="_top">http://opencontent.org/openpub/</a>. | |
| 82 | </p></div></div></body></html> |