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glUseProgram.xhtml
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glUseProgram.xhtml
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<div class="refentry" lang="en" xml:lang="en"><a id="glUseProgram"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glUseProgram — Installs a program object as part of current rendering state</p></div><div class="refsynopsisdiv"><h2>C Specification</h2><div class="funcsynopsis"><table><tr><td><code class="funcdef">void <b class="fsfunc">glUseProgram</b>(</code></td><td>GLuint </td><td><var class="pdparam">program</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
whose executables are to be used as part of current
rendering state.</p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p><code class="function">glUseProgram</code> installs the program
object specified by <em class="parameter"><code>program</code></em> as part of
current rendering state. One or more executables are created in
a program object by successfully attaching shader objects to it
with
<a class="citerefentry" href="glAttachShader"><span class="citerefentry"><span class="refentrytitle">glAttachShader</span></span></a>,
successfully compiling the shader objects with
<a class="citerefentry" href="glCompileShader"><span class="citerefentry"><span class="refentrytitle">glCompileShader</span></span></a>,
and successfully linking the program object with
<a class="citerefentry" href="glLinkProgram"><span class="citerefentry"><span class="refentrytitle">glLinkProgram</span></span></a>.
</p><p>A program object will contain an executable that will run
on the vertex processor if it contains one or more shader
objects of type <code class="constant">GL_VERTEX_SHADER</code> that have
been successfully compiled and linked. Similarly, a program
object will contain an executable that will run on the fragment
processor if it contains one or more shader objects of type
<code class="constant">GL_FRAGMENT_SHADER</code> that have been
successfully compiled and linked.</p><p>Successfully installing an executable on a programmable
processor will cause the corresponding fixed functionality of
OpenGL to be disabled. Specifically, if an executable is
installed on the vertex processor, the OpenGL fixed
functionality will be disabled as follows.</p><div class="itemizedlist"><ul><li><p>The modelview matrix is not applied to vertex
coordinates.</p></li><li><p>The projection matrix is not applied to vertex
coordinates.</p></li><li><p>The texture matrices are not applied to texture
coordinates.</p></li><li><p>Normals are not transformed to eye
coordinates.</p></li><li><p>Normals are not rescaled or normalized.</p></li><li><p>Normalization of
<code class="constant">GL_AUTO_NORMAL</code> evaluated normals is
not performed.</p></li><li><p>Texture coordinates are not generated
automatically.</p></li><li><p>Per-vertex lighting is not performed.</p></li><li><p>Color material computations are not
performed.</p></li><li><p>Color index lighting is not performed.</p></li><li><p>This list also applies when setting the current
raster position.</p></li></ul></div><p>The executable that is installed on the vertex processor
is expected to implement any or all of the desired functionality
from the preceding list. Similarly, if an executable is
installed on the fragment processor, the OpenGL fixed
functionality will be disabled as follows.</p><div class="itemizedlist"><ul><li><p>Texture environment and texture functions are not
applied.</p></li><li><p>Texture application is not applied.</p></li><li><p>Color sum is not applied.</p></li><li><p>Fog is not applied.</p></li></ul></div><p>Again, the fragment shader that is installed is expected
to implement any or all of the desired functionality from the
preceding list.</p><p>While a program object is in use, applications are free to
modify attached shader objects, compile attached shader objects,
attach additional shader objects, and detach or delete shader
objects. None of these operations will affect the executables
that are part of the current state. However, relinking the
program object that is currently in use will install the program
object as part of the current rendering state if the link
operation was successful (see
<a class="citerefentry" href="glLinkProgram"><span class="citerefentry"><span class="refentrytitle">glLinkProgram</span></span></a>
). If the program object currently in use is relinked
unsuccessfully, its link status will be set to
<code class="constant">GL_FALSE</code>, but the executables and
associated state will remain part of the current state until a
subsequent call to <code class="function">glUseProgram</code> removes it
from use. After it is removed from use, it cannot be made part
of current state until it has been successfully relinked.</p><p>If <em class="parameter"><code>program</code></em> contains shader objects
of type <code class="constant">GL_VERTEX_SHADER</code> but it does not
contain shader objects of type
<code class="constant">GL_FRAGMENT_SHADER</code>, an executable will be
installed on the vertex processor, but fixed functionality will
be used for fragment processing. Similarly, if
<em class="parameter"><code>program</code></em> contains shader objects of type
<code class="constant">GL_FRAGMENT_SHADER</code> but it does not contain
shader objects of type <code class="constant">GL_VERTEX_SHADER</code>, an
executable will be installed on the fragment processor, but
fixed functionality will be used for vertex processing. If
<em class="parameter"><code>program</code></em> is 0, the programmable processors
will be disabled, and fixed functionality will be used for both
vertex and fragment processing.</p></div><div class="refsect1" lang="en" xml:lang="en"><a id="notes"></a><h2>Notes</h2><p><code class="function">glUseProgram</code> is available only if the
GL version is 2.0 or greater.</p><p>While a program object is in use, the state that controls
the disabled fixed functionality may also be updated using the
normal OpenGL calls.</p><p>Like display lists and texture objects, the name space for
program objects may be shared across a set of contexts, as long
as the server sides of the contexts share the same address
space. If the name space is shared across contexts, any attached
objects and the data associated with those attached objects are
shared as well.</p><p>Applications are responsible for providing the
synchronization across API calls when objects are accessed from
different execution threads.</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>program</code></em> is neither 0 nor 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
<em class="parameter"><code>program</code></em> could not be made part of current
state.</p><p><code class="constant">GL_INVALID_OPERATION</code> is generated if
<code class="function">glUseProgram</code> is executed between the
execution of
<a class="citerefentry" href="glBegin"><span class="citerefentry"><span class="refentrytitle">glBegin</span></span></a>
and the corresponding execution of
<a class="citerefentry" href="glEnd"><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"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a>
with the argument <code class="constant">GL_CURRENT_PROGRAM</code></p><p><a class="citerefentry" href="glGetActiveAttrib"><span class="citerefentry"><span class="refentrytitle">glGetActiveAttrib</span></span></a>
with a valid program object and the index of an active attribute
variable</p><p><a class="citerefentry" href="glGetActiveUniform"><span class="citerefentry"><span class="refentrytitle">glGetActiveUniform</span></span></a>
with a valid program object and the index of an active uniform
variable</p><p><a class="citerefentry" href="glGetAttachedShaders"><span class="citerefentry"><span class="refentrytitle">glGetAttachedShaders</span></span></a>
with a valid program object</p><p><a class="citerefentry" href="glGetAttribLocation"><span class="citerefentry"><span class="refentrytitle">glGetAttribLocation</span></span></a>
with a valid program object and the name of an attribute
variable</p><p><a class="citerefentry" href="glGetProgram"><span class="citerefentry"><span class="refentrytitle">glGetProgram</span></span></a>
with a valid program object and the parameter to be queried</p><p><a class="citerefentry" href="glGetProgramInfoLog"><span class="citerefentry"><span class="refentrytitle">glGetProgramInfoLog</span></span></a>
with a valid program object</p><p><a class="citerefentry" href="glGetUniform"><span class="citerefentry"><span class="refentrytitle">glGetUniform</span></span></a>
with a valid program object and the location of a uniform
variable</p><p><a class="citerefentry" href="glGetUniformLocation"><span class="citerefentry"><span class="refentrytitle">glGetUniformLocation</span></span></a>
with a valid program object and the name of a uniform
variable</p><p><a class="citerefentry" href="glIsProgram"><span class="citerefentry"><span class="refentrytitle">glIsProgram</span></span></a></p></div>
{$pipelinestall}{$examples}
<div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p><a class="citerefentry" href="gllAttachShader"><span class="citerefentry"><span class="refentrytitle">gllAttachShader</span></span></a>,
<a class="citerefentry" href="glBindAttribLocation"><span class="citerefentry"><span class="refentrytitle">glBindAttribLocation</span></span></a>,
<a class="citerefentry" href="glCompileShader"><span class="citerefentry"><span class="refentrytitle">glCompileShader</span></span></a>,
<a class="citerefentry" href="glCreateProgram"><span class="citerefentry"><span class="refentrytitle">glCreateProgram</span></span></a>,
<a class="citerefentry" href="glDeleteProgram"><span class="citerefentry"><span class="refentrytitle">glDeleteProgram</span></span></a>,
<a class="citerefentry" href="glDetachShader"><span class="citerefentry"><span class="refentrytitle">glDetachShader</span></span></a>,
<a class="citerefentry" href="glLinkProgram"><span class="citerefentry"><span class="refentrytitle">glLinkProgram</span></span></a>,
<a class="citerefentry" href="glUniform"><span class="citerefentry"><span class="refentrytitle">glUniform</span></span></a>,
<a class="citerefentry" href="glValidateProgram"><span class="citerefentry"><span class="refentrytitle">glValidateProgram</span></span></a>,
<a class="citerefentry" href="glVertexAttrib"><span class="citerefentry"><span class="refentrytitle">glVertexAttrib</span></span></a></p></div><div class="refsect1" lang="en" xml:lang="en"><div id="Copyright"><h2>Copyright</h2><p>
Copyright © 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="https://opencontent.org/openpub/" target="_top">https://opencontent.org/openpub/</a>.
</p></div></div></div>