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4 Reference Pages
</title><meta name=
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"refentry" lang=
"en" xml:
lang=
"en"><a id=
"glHint"></a><div class=
"titlepage"></div><div class=
"refnamediv"><h2>Name
</h2><p>glHint — specify implementation-specific hints
</p></div><div class=
"refsynopsisdiv"><h2>C Specification
</h2><div class=
"funcsynopsis"><p><code class=
"funcdef">void
<b class=
"fsfunc">glHint
</b>(
</code>GLenum
<var class=
"pdparam">target
</var>, GLenum
<var class=
"pdparam">mode
</var><code>)
</code>;
</p></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>target
</code></em></span></dt><dd><p>
5 Specifies a symbolic constant indicating the behavior to be controlled.
6 <code class=
"constant">GL_LINE_SMOOTH_HINT
</code>,
7 <code class=
"constant">GL_POLYGON_SMOOTH_HINT
</code>,
8 <code class=
"constant">GL_TEXTURE_COMPRESSION_HINT
</code>, and
9 <code class=
"constant">GL_FRAGMENT_SHADER_DERIVATIVE_HINT
</code>
11 </p></dd><dt><span class=
"term"><em class=
"parameter"><code>mode
</code></em></span></dt><dd><p>
12 Specifies a symbolic constant indicating the desired behavior.
13 <code class=
"constant">GL_FASTEST
</code>,
14 <code class=
"constant">GL_NICEST
</code>, and
15 <code class=
"constant">GL_DONT_CARE
</code> are accepted.
16 </p></dd></dl></div></div><div class=
"refsect1" lang=
"en" xml:
lang=
"en"><a id=
"description"></a><h2>Description
</h2><p>
17 Certain aspects of GL behavior,
18 when there is room for interpretation,
19 can be controlled with hints.
20 A hint is specified with two arguments.
21 <em class=
"parameter"><code>target
</code></em> is a symbolic
22 constant indicating the behavior to be controlled,
23 and
<em class=
"parameter"><code>mode
</code></em> is another symbolic constant indicating the desired
24 behavior. The initial value for each
<em class=
"parameter"><code>target
</code></em> is
<code class=
"constant">GL_DONT_CARE
</code>.
25 <em class=
"parameter"><code>mode
</code></em> can be one of the following:
26 </p><div class=
"variablelist"><dl><dt><span class=
"term"><code class=
"constant">GL_FASTEST
</code></span></dt><dd><p>
28 The most efficient option should be chosen.
29 </p></dd><dt><span class=
"term"><code class=
"constant">GL_NICEST
</code></span></dt><dd><p>
33 option should be chosen.
34 </p></dd><dt><span class=
"term"><code class=
"constant">GL_DONT_CARE
</code></span></dt><dd><p>
37 </p></dd></dl></div><p>
38 Though the implementation aspects that can be hinted are well defined,
39 the interpretation of the hints depends on the implementation.
40 The hint aspects that can be specified with
<em class=
"parameter"><code>target
</code></em>,
41 along with suggested semantics,
43 </p><div class=
"variablelist"><dl><dt><span class=
"term"><code class=
"constant">GL_FRAGMENT_SHADER_DERIVATIVE_HINT
</code></span></dt><dd><p>
45 Indicates the accuracy of the derivative calculation for the GL shading language fragment processing built-in functions:
46 <code class=
"constant">dFdx
</code>,
<code class=
"constant">dFdy
</code>, and
<code class=
"constant">fwidth
</code>.
47 </p></dd><dt><span class=
"term"><code class=
"constant">GL_LINE_SMOOTH_HINT
</code></span></dt><dd><p>
49 Indicates the sampling quality of antialiased lines.
50 If a larger filter function is applied, hinting
<code class=
"constant">GL_NICEST
</code> can
51 result in more pixel fragments being generated during rasterization.
52 </p></dd><dt><span class=
"term"><code class=
"constant">GL_POLYGON_SMOOTH_HINT
</code></span></dt><dd><p>
54 Indicates the sampling quality of antialiased polygons.
55 Hinting
<code class=
"constant">GL_NICEST
</code> can result in more pixel fragments being generated
57 if a larger filter function is applied.
58 </p></dd><dt><span class=
"term"><code class=
"constant">GL_TEXTURE_COMPRESSION_HINT
</code></span></dt><dd><p>
60 Indicates the quality and performance of the compressing texture images.
61 Hinting
<code class=
"constant">GL_FASTEST
</code> indicates that texture images should be compressed
62 as quickly as possible, while
<code class=
"constant">GL_NICEST
</code> indicates that texture images
63 should be compressed with as little image quality loss as possible.
64 <code class=
"constant">GL_NICEST
</code> should be selected if the texture is to be retrieved by
65 <a href=
"glGetCompressedTexImage.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glGetCompressedTexImage
</span></span></a> for reuse.
66 </p></dd></dl></div></div><div class=
"refsect1" lang=
"en" xml:
lang=
"en"><a id=
"notes"></a><h2>Notes
</h2><p>
67 The interpretation of hints depends on the implementation.
68 Some implementations ignore
<code class=
"function">glHint
</code> settings.
69 </p></div><div class=
"refsect1" lang=
"en" xml:
lang=
"en"><a id=
"errors"></a><h2>Errors
</h2><p>
70 <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
72 </p></div><div class=
"refsect1" lang=
"en" xml:
lang=
"en"><a id=
"Copyright"></a><h2>Copyright
</h2><p>
73 Copyright
<span class=
"trademark"></span>©
1991-
2006
74 Silicon Graphics, Inc. This document is licensed under the SGI
75 Free Software B License. For details, see
76 <a href=
"http://oss.sgi.com/projects/FreeB/" target=
"_top">http://oss.sgi.com/projects/FreeB/
</a>.
77 </p></div></div></body></html>