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>glBindAttribLocation</title><meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /></head><body><div class="refentry" lang="en" xml:lang="en"><a id="glBindAttribLocation"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glBindAttribLocation — Associates a generic vertex attribute index with a named attribute variable</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">glBindAttribLocation</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>const 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 handle of the program object in | |
| 4 | which the association is to be made.</p></dd><dt><span class="term"><em class="parameter"><code>index</code></em></span></dt><dd><p>Specifies the index of the generic vertex | |
| 5 | attribute to be bound.</p></dd><dt><span class="term"><em class="parameter"><code>name</code></em></span></dt><dd><p>Specifies a null terminated string containing | |
| 6 | the name of the vertex shader attribute variable to | |
| 7 | which <em class="parameter"><code>index</code></em> is to be | |
| 8 | bound.</p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p><code class="function">glBindAttribLocation</code> is used to | |
| 9 | associate a user-defined attribute variable in the program | |
| 10 | object specified by <em class="parameter"><code>program</code></em> with a | |
| 11 | generic vertex attribute index. The name of the user-defined | |
| 12 | attribute variable is passed as a null terminated string in | |
| 13 | <em class="parameter"><code>name</code></em>. The generic vertex attribute index | |
| 14 | to be bound to this variable is specified by | |
| 15 | <em class="parameter"><code>index</code></em>. When | |
| 16 | <em class="parameter"><code>program</code></em> is made part of current state, | |
| 17 | values provided via the generic vertex attribute | |
| 18 | <em class="parameter"><code>index</code></em> will modify the value of the | |
| 19 | user-defined attribute variable specified by | |
| 20 | <em class="parameter"><code>name</code></em>.</p><p>If <em class="parameter"><code>name</code></em> refers to a matrix | |
| 21 | attribute variable, <em class="parameter"><code>index</code></em> refers to the | |
| 22 | first column of the matrix. Other matrix columns are then | |
| 23 | automatically bound to locations <em class="parameter"><code>index+1</code></em> | |
| 24 | for a matrix of type mat2; <em class="parameter"><code>index+1</code></em> and | |
| 25 | <em class="parameter"><code>index+2</code></em> for a matrix of type mat3; and | |
| 26 | <em class="parameter"><code>index+1</code></em>, <em class="parameter"><code>index+2</code></em>, | |
| 27 | and <em class="parameter"><code>index+3</code></em> for a matrix of type | |
| 28 | mat4.</p><p>This command makes it possible for vertex shaders to use | |
| 29 | descriptive names for attribute variables rather than generic | |
| 30 | variables that are numbered from 0 to | |
| 31 | <code class="constant">GL_MAX_VERTEX_ATTRIBS</code> -1. The values sent | |
| 32 | to each generic attribute index are part of current state, just | |
| 33 | like standard vertex attributes such as color, normal, and | |
| 34 | vertex position. If a different program object is made current | |
| 35 | by calling | |
| 36 | <a class="citerefentry" href="glUseProgram.xml"><span class="citerefentry"><span class="refentrytitle">glUseProgram</span></span></a>, | |
| 37 | the generic vertex attributes are tracked in such a way that the | |
| 38 | same values will be observed by attributes in the new program | |
| 39 | object that are also bound to | |
| 40 | <em class="parameter"><code>index</code></em>.</p><p>Attribute variable | |
| 41 | name-to-generic attribute index bindings for a program object | |
| 42 | can be explicitly assigned at any time by calling | |
| 43 | <code class="function">glBindAttribLocation</code>. Attribute bindings do | |
| 44 | not go into effect until | |
| 45 | <a class="citerefentry" href="glLinkProgram.xml"><span class="citerefentry"><span class="refentrytitle">glLinkProgram</span></span></a> | |
| 46 | is called. After a program object has been linked successfully, | |
| 47 | the index values for generic attributes remain fixed (and their | |
| 48 | values can be queried) until the next link command | |
| 49 | occurs.</p><p>Applications are not allowed to bind any of the standard | |
| 50 | OpenGL vertex attributes using this command, as they are bound | |
| 51 | automatically when needed. Any attribute binding that occurs | |
| 52 | after the program object has been linked will not take effect | |
| 53 | until the next time the program object is linked.</p></div><div class="refsect1" lang="en" xml:lang="en"><a id="notes"></a><h2>Notes</h2><p><code class="function">glBindAttribLocation</code> is available | |
| 54 | only if the GL version is 2.0 or greater.</p><p><code class="function">glBindAttribLocation</code> can be called | |
| 55 | before any vertex shader objects are bound to the specified | |
| 56 | program object. It is also permissible to bind a generic | |
| 57 | attribute index to an attribute variable name that is never used | |
| 58 | in a vertex shader.</p><p>If <em class="parameter"><code>name</code></em> was bound previously, that | |
| 59 | information is lost. Thus you cannot bind one user-defined | |
| 60 | attribute variable to multiple indices, but you can bind | |
| 61 | multiple user-defined attribute variables to the same | |
| 62 | index.</p><p>Applications are allowed to bind more than one | |
| 63 | user-defined attribute variable to the same generic vertex | |
| 64 | attribute index. This is called <span class="emphasis"><em>aliasing</em></span>, | |
| 65 | and it is allowed only if just one of the aliased attributes is | |
| 66 | active in the executable program, or if no path through the | |
| 67 | shader consumes more than one attribute of a set of attributes | |
| 68 | aliased to the same location. The compiler and linker are | |
| 69 | allowed to assume that no aliasing is done and are free to | |
| 70 | employ optimizations that work only in the absence of aliasing. | |
| 71 | OpenGL implementations are not required to do error checking to | |
| 72 | detect aliasing. Because there is no way to bind standard | |
| 73 | attributes, it is not possible to alias generic attributes with | |
| 74 | conventional ones (except for generic attribute 0).</p><p>Active attributes that are not explicitly bound will be | |
| 75 | bound by the linker when | |
| 76 | <a class="citerefentry" href="glLinkProgram.xml"><span class="citerefentry"><span class="refentrytitle">glLinkProgram</span></span></a> | |
| 77 | is called. The locations assigned can be queried by calling | |
| 78 | <a class="citerefentry" href="glGetAttribLocation.xml"><span class="citerefentry"><span class="refentrytitle">glGetAttribLocation</span></span></a>.</p><p>OpenGL copies the <em class="parameter"><code>name</code></em> string when | |
| 79 | <code class="function">glBindAttribLocation</code> is called, so an | |
| 80 | application may free its copy of the <em class="parameter"><code>name</code></em> | |
| 81 | string immediately after the function returns.</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 | |
| 82 | <em class="parameter"><code>index</code></em> is greater than or equal to | |
| 83 | <code class="constant">GL_MAX_VERTEX_ATTRIBS</code>.</p><p><code class="constant">GL_INVALID_OPERATION</code> is generated if | |
| 84 | <em class="parameter"><code>name</code></em> starts with the reserved prefix | |
| 85 | "gl_".</p><p><code class="constant">GL_INVALID_VALUE</code> is generated if | |
| 86 | <em class="parameter"><code>program</code></em> is not a value generated by | |
| 87 | OpenGL.</p><p><code class="constant">GL_INVALID_OPERATION</code> is generated if | |
| 88 | <em class="parameter"><code>program</code></em> is not a program object.</p><p><code class="constant">GL_INVALID_OPERATION</code> is generated if | |
| 89 | <code class="function">glBindAttribLocation</code> is executed between | |
| 90 | the execution of | |
| 91 | <a class="citerefentry" href="glBegin.xml"><span class="citerefentry"><span class="refentrytitle">glBegin</span></span></a> | |
| 92 | and the corresponding execution of | |
| 93 | <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> | |
| 94 | with argument <code class="constant">GL_MAX_VERTEX_ATTRIBS</code></p><p><a class="citerefentry" href="glGetActiveAttrib.xml"><span class="citerefentry"><span class="refentrytitle">glGetActiveAttrib</span></span></a> | |
| 95 | with argument <em class="parameter"><code>program</code></em></p><p><a class="citerefentry" href="glGetAttribLocation.xml"><span class="citerefentry"><span class="refentrytitle">glGetAttribLocation</span></span></a> | |
| 96 | with arguments <em class="parameter"><code>program</code></em> and | |
| 97 | <em class="parameter"><code>name</code></em></p><p><a class="citerefentry" 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 class="citerefentry" href="glDisableVertexAttribArray.xml"><span class="citerefentry"><span class="refentrytitle">glDisableVertexAttribArray</span></span></a>, | |
| 98 | <a class="citerefentry" href="glEnableVertexAttribArray.xml"><span class="citerefentry"><span class="refentrytitle">glEnableVertexAttribArray</span></span></a>, | |
| 99 | <a class="citerefentry" href="glUseProgram.xml"><span class="citerefentry"><span class="refentrytitle">glUseProgram</span></span></a>, | |
| 100 | <a class="citerefentry" href="glVertexAttrib.xml"><span class="citerefentry"><span class="refentrytitle">glVertexAttrib</span></span></a>, | |
| 101 | <a class="citerefentry" 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> | |
| 102 | Copyright <span class="trademark"></span>© 2003-2005 3Dlabs Inc. Ltd. | |
| 103 | This material may be distributed subject to the terms and conditions set forth in | |
| 104 | the Open Publication License, v 1.0, 8 June 1999. | |
| 105 | <a class="ulink" href="http://opencontent.org/openpub/" target="_top">http://opencontent.org/openpub/</a>. | |
| 106 | </p></div></div></body></html> |