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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>glMinmax</title><meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /></head><body><div class="refentry" lang="en" xml:lang="en"><a id="glMinmax"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glMinmax — define minmax table</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">glMinmax</b>(</code></td><td>GLenum </td><td><var class="pdparam">target</var>, </td></tr><tr><td> </td><td>GLenum </td><td><var class="pdparam">internalformat</var>, </td></tr><tr><td> </td><td>GLboolean </td><td><var class="pdparam">sink</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>target</code></em></span></dt><dd><p> | |
4 | The minmax table whose parameters are to be set. | |
5 | Must be | |
6 | <code class="constant">GL_MINMAX</code>. | |
7 | </p></dd><dt><span class="term"><em class="parameter"><code>internalformat</code></em></span></dt><dd><p> | |
8 | The format of entries in the minmax table. | |
9 | Must be one of | |
10 | <code class="constant">GL_ALPHA</code>, | |
11 | <code class="constant">GL_ALPHA4</code>, | |
12 | <code class="constant">GL_ALPHA8</code>, | |
13 | <code class="constant">GL_ALPHA12</code>, | |
14 | <code class="constant">GL_ALPHA16</code>, | |
15 | <code class="constant">GL_LUMINANCE</code>, | |
16 | <code class="constant">GL_LUMINANCE4</code>, | |
17 | <code class="constant">GL_LUMINANCE8</code>, | |
18 | <code class="constant">GL_LUMINANCE12</code>, | |
19 | <code class="constant">GL_LUMINANCE16</code>, | |
20 | <code class="constant">GL_LUMINANCE_ALPHA</code>, | |
21 | <code class="constant">GL_LUMINANCE4_ALPHA4</code>, | |
22 | <code class="constant">GL_LUMINANCE6_ALPHA2</code>, | |
23 | <code class="constant">GL_LUMINANCE8_ALPHA8</code>, | |
24 | <code class="constant">GL_LUMINANCE12_ALPHA4</code>, | |
25 | <code class="constant">GL_LUMINANCE12_ALPHA12</code>, | |
26 | <code class="constant">GL_LUMINANCE16_ALPHA16</code>, | |
27 | <code class="constant">GL_R3_G3_B2</code>, | |
28 | <code class="constant">GL_RGB</code>, | |
29 | <code class="constant">GL_RGB4</code>, | |
30 | <code class="constant">GL_RGB5</code>, | |
31 | <code class="constant">GL_RGB8</code>, | |
32 | <code class="constant">GL_RGB10</code>, | |
33 | <code class="constant">GL_RGB12</code>, | |
34 | <code class="constant">GL_RGB16</code>, | |
35 | <code class="constant">GL_RGBA</code>, | |
36 | <code class="constant">GL_RGBA2</code>, | |
37 | <code class="constant">GL_RGBA4</code>, | |
38 | <code class="constant">GL_RGB5_A1</code>, | |
39 | <code class="constant">GL_RGBA8</code>, | |
40 | <code class="constant">GL_RGB10_A2</code>, | |
41 | <code class="constant">GL_RGBA12</code>, or | |
42 | <code class="constant">GL_RGBA16</code>. | |
43 | </p></dd><dt><span class="term"><em class="parameter"><code>sink</code></em></span></dt><dd><p> | |
44 | If <code class="constant">GL_TRUE</code>, pixels will be consumed by the minmax | |
45 | process and no drawing or texture loading will take place. | |
46 | If <code class="constant">GL_FALSE</code>, pixels will proceed to the final conversion process after | |
47 | minmax. | |
48 | </p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p> | |
49 | When <code class="constant">GL_MINMAX</code> is enabled, the RGBA components of incoming pixels are | |
50 | compared to the minimum and maximum values for each component, which are | |
51 | stored in the two-element minmax table. | |
52 | (The first element stores the minima, and the second element stores | |
53 | the maxima.) | |
54 | If a pixel component is greater than the corresponding component | |
55 | in the maximum element, then the maximum element is updated with the | |
56 | pixel component value. | |
57 | If a pixel component is less than the corresponding component in | |
58 | the minimum element, then the minimum element is updated with the | |
59 | pixel component value. | |
60 | (In both cases, if the internal format of the minmax table includes | |
61 | luminance, then the R color component of incoming pixels is used | |
62 | for comparison.) | |
63 | The contents of the minmax table may be retrieved at a later time | |
64 | by calling <a class="citerefentry" href="glGetMinmax.xml"><span class="citerefentry"><span class="refentrytitle">glGetMinmax</span></span></a>. | |
65 | The minmax operation is enabled or disabled by calling <a class="citerefentry" href="glEnable.xml"><span class="citerefentry"><span class="refentrytitle">glEnable</span></span></a> or | |
66 | <a class="citerefentry" href="glDisable.xml"><span class="citerefentry"><span class="refentrytitle">glDisable</span></span></a>, respectively, with an argument of <code class="constant">GL_MINMAX</code>. | |
67 | </p><p> | |
68 | <code class="function">glMinmax</code> redefines the current minmax table to have entries of the format | |
69 | specified by <em class="parameter"><code>internalformat</code></em>. | |
70 | The maximum element is initialized with the smallest possible component | |
71 | values, and the minimum element is initialized with the largest possible | |
72 | component values. | |
73 | The values in the previous minmax table, if any, are lost. | |
74 | If <em class="parameter"><code>sink</code></em> is <code class="constant">GL_TRUE</code>, then pixels are discarded after minmax; | |
75 | no further processing of the pixels takes place, and no drawing, | |
76 | texture loading, or pixel readback will result. | |
77 | </p><p> | |
78 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="notes"></a><h2>Notes</h2><p> | |
79 | <code class="function">glMinmax</code> is present only if <code class="code">ARB_imaging</code> is returned when <a class="citerefentry" href="glGetString.xml"><span class="citerefentry"><span class="refentrytitle">glGetString</span></span></a> | |
80 | is called with an argument of <code class="constant">GL_EXTENSIONS</code>. | |
81 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="errors"></a><h2>Errors</h2><p> | |
82 | <code class="constant">GL_INVALID_ENUM</code> is generated if <em class="parameter"><code>target</code></em> is not one of the allowable | |
83 | values. | |
84 | </p><p> | |
85 | <code class="constant">GL_INVALID_ENUM</code> is generated if <em class="parameter"><code>internalformat</code></em> is not one of the | |
86 | allowable values. | |
87 | </p><p> | |
88 | <code class="constant">GL_INVALID_OPERATION</code> is generated if <code class="function">glMinmax</code> is executed | |
89 | between the execution of <a class="citerefentry" href="glBegin.xml"><span class="citerefentry"><span class="refentrytitle">glBegin</span></span></a> and the corresponding | |
90 | execution of <a class="citerefentry" href="glEnd.xml"><span class="citerefentry"><span class="refentrytitle">glEnd</span></span></a>. | |
91 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="associatedgets"></a><h2>Associated Gets</h2><p> | |
92 | <a class="citerefentry" href="glGetMinmaxParameter.xml"><span class="citerefentry"><span class="refentrytitle">glGetMinmaxParameter</span></span></a> | |
93 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p> | |
94 | <a class="citerefentry" href="glGetMinmax.xml"><span class="citerefentry"><span class="refentrytitle">glGetMinmax</span></span></a>, | |
95 | <a class="citerefentry" href="glResetMinmax.xml"><span class="citerefentry"><span class="refentrytitle">glResetMinmax</span></span></a> | |
96 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="Copyright"></a><h2>Copyright</h2><p> | |
97 | Copyright <span class="trademark"></span>© 1991-2006 | |
98 | Silicon Graphics, Inc. This document is licensed under the SGI | |
99 | Free Software B License. For details, see | |
100 | <a class="ulink" href="http://oss.sgi.com/projects/FreeB/" target="_top">http://oss.sgi.com/projects/FreeB/</a>. | |
101 | </p></div></div></body></html> |