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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>glSampleCoverage</title><meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /></head><body><div class="refentry" lang="en" xml:lang="en"><a id="glSampleCoverage"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glSampleCoverage — specify multisample coverage parameters</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">glSampleCoverage</b>(</code></td><td>GLclampf </td><td><var class="pdparam">value</var>, </td></tr><tr><td> </td><td>GLboolean </td><td><var class="pdparam">invert</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>value</code></em></span></dt><dd><p> | |
4 | Specify a single floating-point sample coverage value. The value is | |
5 | clamped to the range | |
6 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
7 | ||
8 | <mml:mfenced open="[" close="]"> | |
9 | <mml:mn>0</mml:mn> | |
10 | <mml:mn>1</mml:mn> | |
11 | </mml:mfenced> | |
12 | </mml:math>. | |
13 | The initial value is 1.0. | |
14 | </p></dd><dt><span class="term"><em class="parameter"><code>invert</code></em></span></dt><dd><p> | |
15 | Specify a single boolean value representing if the coverage masks should be | |
16 | inverted. <code class="constant">GL_TRUE</code> and <code class="constant">GL_FALSE</code> are accepted. The initial value | |
17 | is <code class="constant">GL_FALSE</code>. | |
18 | </p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p> | |
19 | Multisampling samples a pixel multiple times at various | |
20 | implementation-dependent subpixel locations to generate antialiasing | |
21 | effects. Multisampling transparently antialiases points, lines, polygons, | |
22 | bitmaps, and images if it is enabled. | |
23 | </p><p> | |
24 | <em class="parameter"><code>value</code></em> is used in constructing a temporary mask used in determining which | |
25 | samples will be used in resolving the final fragment color. This mask is | |
26 | bitwise-anded with the coverage mask generated from the multisampling | |
27 | computation. If the <em class="parameter"><code>invert</code></em> flag is set, the temporary mask is inverted | |
28 | (all bits flipped) and then the bitwise-and is computed. | |
29 | </p><p> | |
30 | If an implementation does not have any multisample buffers available, or | |
31 | multisampling is disabled, rasterization occurs with only a single sample | |
32 | computing a pixel's final RGB color. | |
33 | </p><p> | |
34 | Provided an implementation supports multisample buffers, and multisampling | |
35 | is enabled, then a pixel's final color is generated by combining several | |
36 | samples per pixel. Each sample contains color, depth, and stencil | |
37 | information, allowing those operations to be performed on each sample. | |
38 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="notes"></a><h2>Notes</h2><p> | |
39 | <code class="function">glSampleCoverage</code> is available only if the GL version is 1.3 or greater. | |
40 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="errors"></a><h2>Errors</h2><p> | |
41 | <code class="constant">GL_INVALID_OPERATION</code> is generated if <code class="function">glSampleCoverage</code> is executed between the | |
42 | 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>. | |
43 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="associatedgets"></a><h2>Associated Gets</h2><p> | |
44 | <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_SAMPLE_COVERAGE_VALUE</code> | |
45 | </p><p> | |
46 | <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_SAMPLE_COVERAGE_INVERT</code> | |
47 | </p><p> | |
48 | <a class="citerefentry" href="glIsEnabled.xml"><span class="citerefentry"><span class="refentrytitle">glIsEnabled</span></span></a> with argument <code class="constant">GL_MULTISAMPLE</code> | |
49 | </p><p> | |
50 | <a class="citerefentry" href="glIsEnabled.xml"><span class="citerefentry"><span class="refentrytitle">glIsEnabled</span></span></a> with argument <code class="constant">GL_SAMPLE_ALPHA_TO_COVERAGE</code> | |
51 | </p><p> | |
52 | <a class="citerefentry" href="glIsEnabled.xml"><span class="citerefentry"><span class="refentrytitle">glIsEnabled</span></span></a> with argument <code class="constant">GL_SAMPLE_ALPHA_TO_ONE</code> | |
53 | </p><p> | |
54 | <a class="citerefentry" href="glIsEnabled.xml"><span class="citerefentry"><span class="refentrytitle">glIsEnabled</span></span></a> with argument <code class="constant">GL_SAMPLE_COVERAGE</code> | |
55 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p> | |
56 | <a class="citerefentry" href="glEnable.xml"><span class="citerefentry"><span class="refentrytitle">glEnable</span></span></a>, | |
57 | <a class="citerefentry" href="glPushAttrib.xml"><span class="citerefentry"><span class="refentrytitle">glPushAttrib</span></span></a> | |
58 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="Copyright"></a><h2>Copyright</h2><p> | |
59 | Copyright <span class="trademark"></span>© 1991-2006 | |
60 | Silicon Graphics, Inc. This document is licensed under the SGI | |
61 | Free Software B License. For details, see | |
62 | <a class="ulink" href="http://oss.sgi.com/projects/FreeB/" target="_top">http://oss.sgi.com/projects/FreeB/</a>. | |
63 | </p></div></div></body></html> |