HCoop / clinton / guile-figl.git / blame
| Commit | Line | Data |
|---|---|---|
| 7faf1d71 AW |
1 | <?xml version="1.0" encoding="UTF-8"?> |
| 2 | <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "xhtml1-transitional.dtd"> | |
| 3 | <!-- saved from url=(0013)about:internet --> | |
| 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>glGetActiveAttrib - OpenGL 4 Reference Pages</title><meta name="generator" content="DocBook XSL Stylesheets V1.69.1" /></head><body><div class="refentry" lang="en" xml:lang="en"><a id="glGetActiveAttrib"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glGetActiveAttrib — Returns information about an active attribute variable for the specified program object</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">glGetActiveAttrib</b>(</code></td><td>GLuint </td><td><var class="pdparam">program</var>, </td></tr><tr><td> </td><td>GLuint </td><td><var class="pdparam">index</var>, </td></tr><tr><td> </td><td>GLsizei </td><td><var class="pdparam">bufSize</var>, </td></tr><tr><td> </td><td>GLsizei * </td><td><var class="pdparam">length</var>, </td></tr><tr><td> </td><td>GLint * </td><td><var class="pdparam">size</var>, </td></tr><tr><td> </td><td>GLenum * </td><td><var class="pdparam">type</var>, </td></tr><tr><td> </td><td>GLchar * </td><td><var class="pdparam">name</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>program</code></em></span></dt><dd><p>Specifies the program object to be | |
| 5 | queried.</p></dd><dt><span class="term"><em class="parameter"><code>index</code></em></span></dt><dd><p>Specifies the index of the attribute variable | |
| 6 | to be queried.</p></dd><dt><span class="term"><em class="parameter"><code>bufSize</code></em></span></dt><dd><p>Specifies the maximum number of characters | |
| 7 | OpenGL is allowed to write in the character buffer | |
| 8 | indicated by <em class="parameter"><code>name</code></em>.</p></dd><dt><span class="term"><em class="parameter"><code>length</code></em></span></dt><dd><p>Returns the number of characters actually | |
| 9 | written by OpenGL in the string indicated by | |
| 10 | <em class="parameter"><code>name</code></em> (excluding the null | |
| 11 | terminator) if a value other than | |
| 12 | <code class="constant">NULL</code> is passed.</p></dd><dt><span class="term"><em class="parameter"><code>size</code></em></span></dt><dd><p>Returns the size of the attribute | |
| 13 | variable.</p></dd><dt><span class="term"><em class="parameter"><code>type</code></em></span></dt><dd><p>Returns the data type of the attribute | |
| 14 | variable.</p></dd><dt><span class="term"><em class="parameter"><code>name</code></em></span></dt><dd><p>Returns a null terminated string containing | |
| 15 | the name of the attribute variable.</p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p><code class="function">glGetActiveAttrib</code> returns information | |
| 16 | about an active attribute variable in the program object | |
| 17 | specified by <em class="parameter"><code>program</code></em>. The number of | |
| 18 | active attributes can be obtained by calling | |
| 19 | <a href="glGetProgram.xml"><span class="citerefentry"><span class="refentrytitle">glGetProgram</span></span></a> | |
| 20 | with the value <code class="constant">GL_ACTIVE_ATTRIBUTES</code>. A | |
| 21 | value of 0 for <em class="parameter"><code>index</code></em> selects the first | |
| 22 | active attribute variable. Permissible values for | |
| 23 | <em class="parameter"><code>index</code></em> range from 0 to the number of | |
| 24 | active attribute variables minus 1.</p><p>A vertex shader may use either built-in attribute | |
| 25 | variables, user-defined attribute variables, or both. Built-in | |
| 26 | attribute variables have a prefix of "gl_" and | |
| 27 | reference conventional OpenGL vertex attribtes (e.g., | |
| 28 | <em class="parameter"><code>gl_Vertex</code></em>, | |
| 29 | <em class="parameter"><code>gl_Normal</code></em>, etc., see the OpenGL Shading | |
| 30 | Language specification for a complete list.) User-defined | |
| 31 | attribute variables have arbitrary names and obtain their values | |
| 32 | through numbered generic vertex attributes. An attribute | |
| 33 | variable (either built-in or user-defined) is considered active | |
| 34 | if it is determined during the link operation that it may be | |
| 35 | accessed during program execution. Therefore, | |
| 36 | <em class="parameter"><code>program</code></em> should have previously been the | |
| 37 | target of a call to | |
| 38 | <a href="glLinkProgram.xml"><span class="citerefentry"><span class="refentrytitle">glLinkProgram</span></span></a>, | |
| 39 | but it is not necessary for it to have been linked | |
| 40 | successfully.</p><p>The size of the character buffer required to store the | |
| 41 | longest attribute variable name in | |
| 42 | <em class="parameter"><code>program</code></em> can be obtained by calling | |
| 43 | <a href="glGetProgram.xml"><span class="citerefentry"><span class="refentrytitle">glGetProgram</span></span></a> | |
| 44 | with the value | |
| 45 | <code class="constant">GL_ACTIVE_ATTRIBUTE_MAX_LENGTH</code>. This value | |
| 46 | should be used to allocate a buffer of sufficient size to store | |
| 47 | the returned attribute name. The size of this character buffer | |
| 48 | is passed in <em class="parameter"><code>bufSize</code></em>, and a pointer to | |
| 49 | this character buffer is passed in | |
| 50 | <em class="parameter"><code>name</code></em>.</p><p><code class="function">glGetActiveAttrib</code> returns the name of | |
| 51 | the attribute variable indicated by | |
| 52 | <em class="parameter"><code>index</code></em>, storing it in the character buffer | |
| 53 | specified by <em class="parameter"><code>name</code></em>. The string returned | |
| 54 | will be null terminated. The actual number of characters written | |
| 55 | into this buffer is returned in <em class="parameter"><code>length</code></em>, | |
| 56 | and this count does not include the null termination character. | |
| 57 | If the length of the returned string is not required, a value of | |
| 58 | <code class="constant">NULL</code> can be passed in the | |
| 59 | <em class="parameter"><code>length</code></em> argument.</p><p>The <em class="parameter"><code>type</code></em> argument specifies a | |
| 60 | pointer to a variable into which the attribute variable's data type | |
| 61 | will be written. The symbolic | |
| 62 | constants <code class="constant">GL_FLOAT</code>, | |
| 63 | <code class="constant">GL_FLOAT_VEC2</code>, | |
| 64 | <code class="constant">GL_FLOAT_VEC3</code>, | |
| 65 | <code class="constant">GL_FLOAT_VEC4</code>, | |
| 66 | <code class="constant">GL_FLOAT_MAT2</code>, | |
| 67 | <code class="constant">GL_FLOAT_MAT3</code>, | |
| 68 | <code class="constant">GL_FLOAT_MAT4</code>, | |
| 69 | <code class="constant">GL_FLOAT_MAT2x3</code>, | |
| 70 | <code class="constant">GL_FLOAT_MAT2x4</code>, | |
| 71 | <code class="constant">GL_FLOAT_MAT3x2</code>, | |
| 72 | <code class="constant">GL_FLOAT_MAT3x4</code>, | |
| 73 | <code class="constant">GL_FLOAT_MAT4x2</code>, | |
| 74 | <code class="constant">GL_FLOAT_MAT4x3</code>, | |
| 75 | <code class="constant">GL_INT</code>, | |
| 76 | <code class="constant">GL_INT_VEC2</code>, | |
| 77 | <code class="constant">GL_INT_VEC3</code>, | |
| 78 | <code class="constant">GL_INT_VEC4</code>, | |
| 79 | <code class="constant">GL_UNSIGNED_INT_VEC</code>, | |
| 80 | <code class="constant">GL_UNSIGNED_INT_VEC2</code>, | |
| 81 | <code class="constant">GL_UNSIGNED_INT_VEC3</code>, | |
| 82 | <code class="constant">GL_UNSIGNED_INT_VEC4</code>, | |
| 83 | <code class="constant">DOUBLE</code>, | |
| 84 | <code class="constant">DOUBLE_VEC2</code>, | |
| 85 | <code class="constant">DOUBLE_VEC3</code>, | |
| 86 | <code class="constant">DOUBLE_VEC4</code>, | |
| 87 | <code class="constant">DOUBLE_MAT2</code>, | |
| 88 | <code class="constant">DOUBLE_MAT3</code>, | |
| 89 | <code class="constant">DOUBLE_MAT4</code>, | |
| 90 | <code class="constant">DOUBLE_MAT2x3</code>, | |
| 91 | <code class="constant">DOUBLE_MAT2x4</code>, | |
| 92 | <code class="constant">DOUBLE_MAT3x2</code>, | |
| 93 | <code class="constant">DOUBLE_MAT3x4</code>, | |
| 94 | <code class="constant">DOUBLE_MAT4x2</code>, or | |
| 95 | <code class="constant">DOUBLE_MAT4x3</code> | |
| 96 | may be returned. The | |
| 97 | <em class="parameter"><code>size</code></em> argument will return the size of the | |
| 98 | attribute, in units of the type returned in | |
| 99 | <em class="parameter"><code>type</code></em>.</p><p>The list of active attribute variables may include both | |
| 100 | built-in attribute variables (which begin with the prefix | |
| 101 | "gl_") as well as user-defined attribute variable | |
| 102 | names.</p><p>This function will return as much information as it can | |
| 103 | about the specified active attribute variable. If no information | |
| 104 | is available, <em class="parameter"><code>length</code></em> will be 0, and | |
| 105 | <em class="parameter"><code>name</code></em> will be an empty string. This | |
| 106 | situation could occur if this function is called after a link | |
| 107 | operation that failed. If an error occurs, the return values | |
| 108 | <em class="parameter"><code>length</code></em>, <em class="parameter"><code>size</code></em>, | |
| 109 | <em class="parameter"><code>type</code></em>, and <em class="parameter"><code>name</code></em> | |
| 110 | will be unmodified.</p></div><div class="refsect1" lang="en" xml:lang="en"><a id="errors"></a><h2>Errors</h2><p><code class="constant">GL_INVALID_VALUE</code> is generated if | |
| 111 | <em class="parameter"><code>program</code></em> is not a value generated by | |
| 112 | OpenGL.</p><p><code class="constant">GL_INVALID_OPERATION</code> is generated if | |
| 113 | <em class="parameter"><code>program</code></em> is not a program object.</p><p><code class="constant">GL_INVALID_VALUE</code> is generated if | |
| 114 | <em class="parameter"><code>index</code></em> is greater than or equal to the | |
| 115 | number of active attribute variables in | |
| 116 | <em class="parameter"><code>program</code></em>.</p><p><code class="constant">GL_INVALID_VALUE</code> is generated if | |
| 117 | <em class="parameter"><code>bufSize</code></em> is less than 0.</p></div><div class="refsect1" lang="en" xml:lang="en"><a id="associatedgets"></a><h2>Associated Gets</h2><p><a href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> | |
| 118 | with argument <code class="constant">GL_MAX_VERTEX_ATTRIBS</code>.</p><p><a href="glGetProgram.xml"><span class="citerefentry"><span class="refentrytitle">glGetProgram</span></span></a> | |
| 119 | with argument <code class="constant">GL_ACTIVE_ATTRIBUTES</code> or | |
| 120 | <code class="constant">GL_ACTIVE_ATTRIBUTE_MAX_LENGTH</code>.</p><p><a href="glIsProgram.xml"><span class="citerefentry"><span class="refentrytitle">glIsProgram</span></span></a></p></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p><a href="glBindAttribLocation.xml"><span class="citerefentry"><span class="refentrytitle">glBindAttribLocation</span></span></a>, | |
| 121 | <a href="glLinkProgram.xml"><span class="citerefentry"><span class="refentrytitle">glLinkProgram</span></span></a>, | |
| 122 | <a href="glVertexAttrib.xml"><span class="citerefentry"><span class="refentrytitle">glVertexAttrib</span></span></a>, | |
| 123 | <a href="glVertexAttribPointer.xml"><span class="citerefentry"><span class="refentrytitle">glVertexAttribPointer</span></span></a></p></div><div class="refsect1" lang="en" xml:lang="en"><a id="Copyright"></a><h2>Copyright</h2><p> | |
| 124 | Copyright <span class="trademark"></span>© 2003-2005 3Dlabs Inc. Ltd. | |
| 125 | Copyright <span class="trademark"></span>© 2010 Khronos Group. | |
| 126 | This material may be distributed subject to the terms and conditions set forth in | |
| 127 | the Open Publication License, v 1.0, 8 June 1999. | |
| 128 | <a href="http://opencontent.org/openpub/" target="_top">http://opencontent.org/openpub/</a>. | |
| 129 | </p></div></div></body></html> |