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-<?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
- 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
- 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
- the name of the vertex shader attribute variable to
- which <em class="parameter"><code>index</code></em> is to be
- 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
- associate a user-defined attribute variable in the program
- object specified by <em class="parameter"><code>program</code></em> with a
- generic vertex attribute index. The name of the user-defined
- attribute variable is passed as a null terminated string in
- <em class="parameter"><code>name</code></em>. The generic vertex attribute index
- to be bound to this variable is specified by
- <em class="parameter"><code>index</code></em>. When
- <em class="parameter"><code>program</code></em> is made part of current state,
- values provided via the generic vertex attribute
- <em class="parameter"><code>index</code></em> will modify the value of the
- user-defined attribute variable specified by
- <em class="parameter"><code>name</code></em>.</p><p>If <em class="parameter"><code>name</code></em> refers to a matrix
- attribute variable, <em class="parameter"><code>index</code></em> refers to the
- first column of the matrix. Other matrix columns are then
- automatically bound to locations <em class="parameter"><code>index+1</code></em>
- for a matrix of type mat2; <em class="parameter"><code>index+1</code></em> and
- <em class="parameter"><code>index+2</code></em> for a matrix of type mat3; and
- <em class="parameter"><code>index+1</code></em>, <em class="parameter"><code>index+2</code></em>,
- and <em class="parameter"><code>index+3</code></em> for a matrix of type
- mat4.</p><p>This command makes it possible for vertex shaders to use
- descriptive names for attribute variables rather than generic
- variables that are numbered from 0 to
- <code class="constant">GL_MAX_VERTEX_ATTRIBS</code> -1. The values sent
- to each generic attribute index are part of current state, just
- like standard vertex attributes such as color, normal, and
- vertex position. If a different program object is made current
- by calling
- <a class="citerefentry" href="glUseProgram.xml"><span class="citerefentry"><span class="refentrytitle">glUseProgram</span></span></a>,
- the generic vertex attributes are tracked in such a way that the
- same values will be observed by attributes in the new program
- object that are also bound to
- <em class="parameter"><code>index</code></em>.</p><p>Attribute variable
- name-to-generic attribute index bindings for a program object
- can be explicitly assigned at any time by calling
- <code class="function">glBindAttribLocation</code>. Attribute bindings do
- not go into effect until
- <a class="citerefentry" href="glLinkProgram.xml"><span class="citerefentry"><span class="refentrytitle">glLinkProgram</span></span></a>
- is called. After a program object has been linked successfully,
- the index values for generic attributes remain fixed (and their
- values can be queried) until the next link command
- occurs.</p><p>Applications are not allowed to bind any of the standard
- OpenGL vertex attributes using this command, as they are bound
- automatically when needed. Any attribute binding that occurs
- after the program object has been linked will not take effect
- 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
- only if the GL version is 2.0 or greater.</p><p><code class="function">glBindAttribLocation</code> can be called
- before any vertex shader objects are bound to the specified
- program object. It is also permissible to bind a generic
- attribute index to an attribute variable name that is never used
- in a vertex shader.</p><p>If <em class="parameter"><code>name</code></em> was bound previously, that
- information is lost. Thus you cannot bind one user-defined
- attribute variable to multiple indices, but you can bind
- multiple user-defined attribute variables to the same
- index.</p><p>Applications are allowed to bind more than one
- user-defined attribute variable to the same generic vertex
- attribute index. This is called <span class="emphasis"><em>aliasing</em></span>,
- and it is allowed only if just one of the aliased attributes is
- active in the executable program, or if no path through the
- shader consumes more than one attribute of a set of attributes
- aliased to the same location. The compiler and linker are
- allowed to assume that no aliasing is done and are free to
- employ optimizations that work only in the absence of aliasing.
- OpenGL implementations are not required to do error checking to
- detect aliasing. Because there is no way to bind standard
- attributes, it is not possible to alias generic attributes with
- conventional ones (except for generic attribute 0).</p><p>Active attributes that are not explicitly bound will be
- bound by the linker when
- <a class="citerefentry" href="glLinkProgram.xml"><span class="citerefentry"><span class="refentrytitle">glLinkProgram</span></span></a>
- is called. The locations assigned can be queried by calling
- <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
- <code class="function">glBindAttribLocation</code> is called, so an
- application may free its copy of the <em class="parameter"><code>name</code></em>
- 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
- <em class="parameter"><code>index</code></em> is greater than or equal to
- <code class="constant">GL_MAX_VERTEX_ATTRIBS</code>.</p><p><code class="constant">GL_INVALID_OPERATION</code> is generated if
- <em class="parameter"><code>name</code></em> starts with the reserved prefix
- "gl_".</p><p><code class="constant">GL_INVALID_VALUE</code> is generated if
- <em class="parameter"><code>program</code></em> is not a value generated by
- OpenGL.</p><p><code class="constant">GL_INVALID_OPERATION</code> is generated if
- <em class="parameter"><code>program</code></em> is not a program object.</p><p><code class="constant">GL_INVALID_OPERATION</code> is generated if
- <code class="function">glBindAttribLocation</code> is executed between
- the execution of
- <a class="citerefentry" href="glBegin.xml"><span class="citerefentry"><span class="refentrytitle">glBegin</span></span></a>
- and the corresponding execution of
- <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>
- 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>
- 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>
- with arguments <em class="parameter"><code>program</code></em> and
- <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>,
- <a class="citerefentry" href="glEnableVertexAttribArray.xml"><span class="citerefentry"><span class="refentrytitle">glEnableVertexAttribArray</span></span></a>,
- <a class="citerefentry" href="glUseProgram.xml"><span class="citerefentry"><span class="refentrytitle">glUseProgram</span></span></a>,
- <a class="citerefentry" href="glVertexAttrib.xml"><span class="citerefentry"><span class="refentrytitle">glVertexAttrib</span></span></a>,
- <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>
- Copyright <span class="trademark"></span>© 2003-2005 3Dlabs Inc. Ltd.
- 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="ulink" href="http://opencontent.org/openpub/" target="_top">http://opencontent.org/openpub/</a>.
- </p></div></div></body></html>
HCoop / clinton / guile-figl.git / blobdiff