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<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE html><html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>glHint - OpenGL 4 Reference Pages</title>
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<header/>
<div class="refentry" id="glHint">
<div class="titlepage"/>
<div class="refnamediv">
<h2>Name</h2>
<p>glHint — specify implementation-specific hints</p>
</div>
<div class="refsynopsisdiv">
<h2>C Specification</h2>
<div class="funcsynopsis">
<table style="border: 0; cellspacing: 0; cellpadding: 0;" class="funcprototype-table">
<tr>
<td>
<code class="funcdef">void <strong class="fsfunc">glHint</strong>(</code>
</td>
<td>GLenum <var class="pdparam">target</var>, </td>
</tr>
<tr>
<td> </td>
<td>GLenum <var class="pdparam">mode</var><code>)</code>;</td>
</tr>
</table>
<div class="funcprototype-spacer"> </div>
</div>
</div>
<div class="refsect1" id="parameters">
<h2>Parameters</h2>
<div class="variablelist">
<dl class="variablelist">
<dt>
<span class="term">
<em class="parameter">
<code>target</code>
</em>
</span>
</dt>
<dd>
<p>
Specifies a symbolic constant indicating the behavior to be controlled.
<code class="constant">GL_LINE_SMOOTH_HINT</code>,
<code class="constant">GL_POLYGON_SMOOTH_HINT</code>,
<code class="constant">GL_TEXTURE_COMPRESSION_HINT</code>, and
<code class="constant">GL_FRAGMENT_SHADER_DERIVATIVE_HINT</code>
are accepted.
</p>
</dd>
<dt>
<span class="term">
<em class="parameter">
<code>mode</code>
</em>
</span>
</dt>
<dd>
<p>
Specifies a symbolic constant indicating the desired behavior.
<code class="constant">GL_FASTEST</code>,
<code class="constant">GL_NICEST</code>, and
<code class="constant">GL_DONT_CARE</code> are accepted.
</p>
</dd>
</dl>
</div>
</div>
<div class="refsect1" id="description">
<h2>Description</h2>
<p>
Certain aspects of GL behavior,
when there is room for interpretation,
can be controlled with hints.
A hint is specified with two arguments.
<em class="parameter"><code>target</code></em> is a symbolic
constant indicating the behavior to be controlled,
and <em class="parameter"><code>mode</code></em> is another symbolic constant indicating the desired
behavior. The initial value for each <em class="parameter"><code>target</code></em> is <code class="constant">GL_DONT_CARE</code>.
<em class="parameter"><code>mode</code></em> can be one of the following:
</p>
<div class="variablelist">
<dl class="variablelist">
<dt>
<span class="term">
<code class="constant">GL_FASTEST</code>
</span>
</dt>
<dd>
<p>
</p>
<p>
The most efficient option should be chosen.
</p>
</dd>
<dt>
<span class="term">
<code class="constant">GL_NICEST</code>
</span>
</dt>
<dd>
<p>
</p>
<p>
The most correct,
or highest quality,
option should be chosen.
</p>
</dd>
<dt>
<span class="term">
<code class="constant">GL_DONT_CARE</code>
</span>
</dt>
<dd>
<p>
</p>
<p>
No preference.
</p>
</dd>
</dl>
</div>
<p>
Though the implementation aspects that can be hinted are well defined,
the interpretation of the hints depends on the implementation.
The hint aspects that can be specified with <em class="parameter"><code>target</code></em>,
along with suggested semantics,
are as follows:
</p>
<div class="variablelist">
<dl class="variablelist">
<dt>
<span class="term">
<code class="constant">GL_FRAGMENT_SHADER_DERIVATIVE_HINT</code>
</span>
</dt>
<dd>
<p>
</p>
<p>
Indicates the accuracy of the derivative calculation for the GL shading language fragment processing built-in functions:
<code class="constant">dFdx</code>, <code class="constant">dFdy</code>, and <code class="constant">fwidth</code>.
</p>
</dd>
<dt>
<span class="term">
<code class="constant">GL_LINE_SMOOTH_HINT</code>
</span>
</dt>
<dd>
<p>
</p>
<p>
Indicates the sampling quality of antialiased lines.
If a larger filter function is applied, hinting <code class="constant">GL_NICEST</code> can
result in more pixel fragments being generated during rasterization.
</p>
</dd>
<dt>
<span class="term">
<code class="constant">GL_POLYGON_SMOOTH_HINT</code>
</span>
</dt>
<dd>
<p>
</p>
<p>
Indicates the sampling quality of antialiased polygons.
Hinting <code class="constant">GL_NICEST</code> can result in more pixel fragments being generated
during rasterization,
if a larger filter function is applied.
</p>
</dd>
<dt>
<span class="term">
<code class="constant">GL_TEXTURE_COMPRESSION_HINT</code>
</span>
</dt>
<dd>
<p>
</p>
<p>
Indicates the quality and performance of the compressing texture images.
Hinting <code class="constant">GL_FASTEST</code> indicates that texture images should be compressed
as quickly as possible, while <code class="constant">GL_NICEST</code> indicates that texture images
should be compressed with as little image quality loss as possible.
<code class="constant">GL_NICEST</code> should be selected if the texture is to be retrieved by
<a class="citerefentry" href="glGetCompressedTexImage.xhtml"><span class="citerefentry"><span class="refentrytitle">glGetCompressedTexImage</span></span></a> for reuse.
</p>
</dd>
</dl>
</div>
</div>
<div class="refsect1" id="notes">
<h2>Notes</h2>
<p>
The interpretation of hints depends on the implementation.
Some implementations ignore <code class="function">glHint</code> settings.
</p>
</div>
<div class="refsect1" id="errors">
<h2>Errors</h2>
<p>
<code class="constant">GL_INVALID_ENUM</code> is generated if either <em class="parameter"><code>target</code></em> or <em class="parameter"><code>mode</code></em> is not
an accepted value.
</p>
</div>
<div class="refsect1" id="versions">
<h2>Version Support</h2>
<div class="informaltable">
<table style="border-collapse: collapse; border-top: 2px solid ; border-bottom: 2px solid ; border-left: 2px solid ; border-right: 2px solid ; ">
<colgroup>
<col style="text-align: left; "/>
<col style="text-align: center; " class="firstvers"/>
<col style="text-align: center; "/>
<col style="text-align: center; "/>
<col style="text-align: center; "/>
<col style="text-align: center; "/>
<col style="text-align: center; "/>
<col style="text-align: center; "/>
<col style="text-align: center; "/>
<col style="text-align: center; "/>
<col style="text-align: center; "/>
<col style="text-align: center; "/>
<col style="text-align: center; " class="lastvers"/>
</colgroup>
<thead>
<tr>
<th style="text-align: left; border-right: 2px solid ; ">
</th>
<th style="text-align: center; border-bottom: 2px solid ; " colspan="12">
<span class="bold"><strong>OpenGL Version</strong></span>
</th>
</tr>
<tr>
<th style="text-align: left; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>Function / Feature Name</strong></span>
</th>
<th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>2.0</strong></span>
</th>
<th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>2.1</strong></span>
</th>
<th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>3.0</strong></span>
</th>
<th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>3.1</strong></span>
</th>
<th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>3.2</strong></span>
</th>
<th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>3.3</strong></span>
</th>
<th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>4.0</strong></span>
</th>
<th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>4.1</strong></span>
</th>
<th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>4.2</strong></span>
</th>
<th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>4.3</strong></span>
</th>
<th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>4.4</strong></span>
</th>
<th style="text-align: center; border-bottom: 2px solid ; ">
<span class="bold"><strong>4.5</strong></span>
</th>
</tr>
</thead>
<tbody>
<tr>
<td style="text-align: left; border-right: 2px solid ; ">
<code class="function">glHint</code>
</td>
<td style="text-align: center; border-right: 2px solid ; ">✔</td>
<td style="text-align: center; border-right: 2px solid ; ">✔</td>
<td style="text-align: center; border-right: 2px solid ; ">✔</td>
<td style="text-align: center; border-right: 2px solid ; ">✔</td>
<td style="text-align: center; border-right: 2px solid ; ">✔</td>
<td style="text-align: center; border-right: 2px solid ; ">✔</td>
<td style="text-align: center; border-right: 2px solid ; ">✔</td>
<td style="text-align: center; border-right: 2px solid ; ">✔</td>
<td style="text-align: center; border-right: 2px solid ; ">✔</td>
<td style="text-align: center; border-right: 2px solid ; ">✔</td>
<td style="text-align: center; border-right: 2px solid ; ">✔</td>
<td style="text-align: center; ">✔</td>
</tr>
</tbody>
</table>
</div>
</div>
<div class="refsect1" id="seealso">
<h2>See Also</h2>
</div>
<div class="refsect1" id="Copyright">
<h2>Copyright</h2>
<p>
Copyright <span class="trademark"/>© 1991-2006 Silicon Graphics, Inc.
Copyright <span class="trademark"/>© 2010-2014 Khronos Group.
This document is licensed under the SGI Free Software B License.
For details, see
<a class="link" href="http://oss.sgi.com/projects/FreeB/" target="_top">http://oss.sgi.com/projects/FreeB/</a>.
</p>
</div>
</div>
<footer/>
</body>
</html>
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