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1 | <?xml version="1.0" encoding="UTF-8"?> |
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4 | <?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" /><link rel="stylesheet" type="text/css" href="opengl-man.css" /><title>glGetActiveUniformBlock</title><meta name="generator" content="DocBook XSL Stylesheets V1.75.2" /></head><body><div class="refentry" title="glGetActiveUniformBlock"><a id="glGetActiveUniformBlock"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glGetActiveUniformBlock — query information about an active uniform block</p></div><div class="refsynopsisdiv" title="C Specification"><h2>C Specification</h2><div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">void <b class="fsfunc">glGetActiveUniformBlockiv</b>(</code></td><td>GLuint <var class="pdparam">program</var>, </td></tr><tr><td> </td><td>GLuint <var class="pdparam">uniformBlockIndex</var>, </td></tr><tr><td> </td><td>GLenum <var class="pdparam">pname</var>, </td></tr><tr><td> </td><td>GLint <var class="pdparam">params</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1" title="Parameters"><a id="parameters"></a><h2>Parameters</h2><div class="variablelist"><dl><dt><span class="term"><em class="parameter"><code>program</code></em></span></dt><dd><p> | |
5 | Specifies the name of a program containing the uniform block. | |
6 | </p></dd><dt><span class="term"><em class="parameter"><code>uniformBlockIndex</code></em></span></dt><dd><p> | |
7 | Specifies the index of the uniform block within <em class="parameter"><code>program</code></em>. | |
8 | </p></dd><dt><span class="term"><em class="parameter"><code>pname</code></em></span></dt><dd><p> | |
9 | Specifies the name of the parameter to query. | |
10 | </p></dd><dt><span class="term"><em class="parameter"><code>params</code></em></span></dt><dd><p> | |
11 | Specifies the address of a variable to receive the result of the query. | |
12 | </p></dd></dl></div></div><div class="refsect1" title="Description"><a id="description"></a><h2>Description</h2><p> | |
13 | <code class="function">glGetActiveUniformBlockiv</code> retrieves information about an active uniform block within <em class="parameter"><code>program</code></em>. | |
14 | </p><p> | |
15 | <em class="parameter"><code>program</code></em> must be the name of a program object for which the command | |
16 | <a class="citerefentry" href="glLinkProgram.xml"><span class="citerefentry"><span class="refentrytitle">glLinkProgram</span></span></a> must have been called in the past, although it is not required that | |
17 | <a class="citerefentry" href="glLinkProgram.xml"><span class="citerefentry"><span class="refentrytitle">glLinkProgram</span></span></a> must have succeeded. The link could have failed because the number | |
18 | of active uniforms exceeded the limit. | |
19 | </p><p> | |
20 | <em class="parameter"><code>uniformBlockIndex</code></em> is an active uniform block index of <em class="parameter"><code>program</code></em>, and must be less than the value | |
21 | of <code class="constant">GL_ACTIVE_UNIFORM_BLOCKS</code>. | |
22 | </p><p> | |
23 | Upon success, the uniform block parameter(s) specified by <em class="parameter"><code>pname</code></em> are returned in <em class="parameter"><code>params</code></em>. If an error | |
24 | occurs, nothing will be written to <em class="parameter"><code>params</code></em>. | |
25 | </p><p> | |
26 | If <em class="parameter"><code>pname</code></em> is <code class="constant">GL_UNIFORM_BLOCK_BINDING</code>, then the index of the uniform buffer binding point | |
27 | last selected by the uniform block specified by <em class="parameter"><code>uniformBlockIndex</code></em> for <em class="parameter"><code>program</code></em> is returned. If | |
28 | no uniform block has been previously specified, zero is returned. | |
29 | </p><p> | |
30 | If <em class="parameter"><code>pname</code></em> is <code class="constant">GL_UNIFORM_BLOCK_DATA_SIZE</code>, then the implementation-dependent minimum total buffer | |
31 | object size, in basic machine units, required to hold all active uniforms in the uniform block identified by <em class="parameter"><code>uniformBlockIndex</code></em> | |
32 | is returned. It is neither guaranteed nor expected that a given implementation will arrange uniform values as tightly packed in a buffer | |
33 | object. The exception to this is the <span class="emphasis"><em>std140 uniform block layout</em></span>, which guarantees specific packing behavior and does not | |
34 | require the application to query for offsets and strides. In this case the minimum size may still be queried, even though it is determined in | |
35 | advance based only on the uniform block declaration. | |
36 | </p><p> | |
37 | If <em class="parameter"><code>pname</code></em> is <code class="constant">GL_UNIFORM_BLOCK_NAME_LENGTH</code>, then the total length (including the nul terminator) of | |
38 | the name of the uniform block identified by <em class="parameter"><code>uniformBlockIndex</code></em> is returned. | |
39 | </p><p> | |
40 | If <em class="parameter"><code>pname</code></em> is <code class="constant">GL_UNIFORM_BLOCK_ACTIVE_UNIFORMS</code>, then the number of active uniforms in the uniform | |
41 | block identified by <em class="parameter"><code>uniformBlockIndex</code></em> is returned. | |
42 | </p><p> | |
43 | If <em class="parameter"><code>pname</code></em> is <code class="constant">GL_UNIFORM_BLOCK_ACTIVE_UNIFORM_INDICES</code>, then a list of the active uniform indices | |
44 | for the uniform block identified by <em class="parameter"><code>uniformBlockIndex</code></em> is returned. The number of elements that will be written to | |
45 | <em class="parameter"><code>params</code></em> is the value of <code class="constant">GL_UNIFORM_BLOCK_ACTIVE_UNIFORMS</code> for <em class="parameter"><code>uniformBlockIndex</code></em>. | |
46 | </p><p> | |
47 | If <em class="parameter"><code>pname</code></em> is <code class="constant">GL_UNIFORM_BLOCK_REFERENCED_BY_VERTEX_SHADER</code>, <code class="constant">GL_UNIFORM_BLOCK_REFERENCED_BY_GEOMETRY_SHADER</code>, | |
48 | or <code class="constant">GL_UNIFORM_BLOCK_REFERENCED_BY_FRAGMENT_SHADER</code>, then a boolean value indicating whether the uniform block identified by | |
49 | <em class="parameter"><code>uniformBlockIndex</code></em> is referenced by the vertex, geometry, or fragment programming stages of program, respectively, is returned. | |
50 | </p></div><div class="refsect1" title="Errors"><a id="errors"></a><h2>Errors</h2><p> | |
51 | <code class="constant">GL_INVALID_VALUE</code> is generated if <em class="parameter"><code>uniformBlockIndex</code></em> is greater than or equal to the value | |
52 | of <code class="constant">GL_ACTIVE_UNIFORM_BLOCKS</code> or is not the index of an active uniform block in <em class="parameter"><code>program</code></em>. | |
53 | </p><p> | |
54 | <code class="constant">GL_INVALID_ENUM</code> is generated if <em class="parameter"><code>pname</code></em> is not one of the accepted tokens. | |
55 | </p><p> | |
56 | <code class="constant">GL_INVALID_OPERATION</code> is generated if <em class="parameter"><code>program</code></em> is not the name of a program object for which | |
57 | <a class="citerefentry" href="glLinkProgram.xml"><span class="citerefentry"><span class="refentrytitle">glLinkProgram</span></span></a> has been called in the past. | |
58 | </p></div><div class="refsect1" title="Notes"><a id="notes"></a><h2>Notes</h2><p> | |
59 | <code class="function">glGetActiveUniformBlockiv</code> is available only if the GL version is 3.1 or greater. | |
60 | </p></div><div class="refsect1" title="See Also"><a id="seealso"></a><h2>See Also</h2><p> | |
61 | <a class="citerefentry" href="glGetActiveUniformBlockName.xml"><span class="citerefentry"><span class="refentrytitle">glGetActiveUniformBlockName</span></span></a>, | |
62 | <a class="citerefentry" href="glGetUniformBlockIndex.xml"><span class="citerefentry"><span class="refentrytitle">glGetUniformBlockIndex</span></span></a>, | |
63 | <a class="citerefentry" href="glLinkProgram.xml"><span class="citerefentry"><span class="refentrytitle">glLinkProgram</span></span></a> | |
64 | </p></div><div class="refsect1" title="Copyright"><a id="Copyright"></a><h2>Copyright</h2><p> | |
65 | Copyright <span class="trademark"></span>© 2010 Khronos Group. | |
66 | This material may be distributed subject to the terms and conditions set forth in | |
67 | the Open Publication License, v 1.0, 8 June 1999. | |
68 | <a class="ulink" href="http://opencontent.org/openpub/" target="_top">http://opencontent.org/openpub/</a>. | |
69 | </p></div></div></body></html> |