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-<?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>
- The minmax table whose parameters are to be set.
- Must be
- <code class="constant">GL_MINMAX</code>.
- </p></dd><dt><span class="term"><em class="parameter"><code>internalformat</code></em></span></dt><dd><p>
- The format of entries in the minmax table.
- Must be one of
- <code class="constant">GL_ALPHA</code>,
- <code class="constant">GL_ALPHA4</code>,
- <code class="constant">GL_ALPHA8</code>,
- <code class="constant">GL_ALPHA12</code>,
- <code class="constant">GL_ALPHA16</code>,
- <code class="constant">GL_LUMINANCE</code>,
- <code class="constant">GL_LUMINANCE4</code>,
- <code class="constant">GL_LUMINANCE8</code>,
- <code class="constant">GL_LUMINANCE12</code>,
- <code class="constant">GL_LUMINANCE16</code>,
- <code class="constant">GL_LUMINANCE_ALPHA</code>,
- <code class="constant">GL_LUMINANCE4_ALPHA4</code>,
- <code class="constant">GL_LUMINANCE6_ALPHA2</code>,
- <code class="constant">GL_LUMINANCE8_ALPHA8</code>,
- <code class="constant">GL_LUMINANCE12_ALPHA4</code>,
- <code class="constant">GL_LUMINANCE12_ALPHA12</code>,
- <code class="constant">GL_LUMINANCE16_ALPHA16</code>,
- <code class="constant">GL_R3_G3_B2</code>,
- <code class="constant">GL_RGB</code>,
- <code class="constant">GL_RGB4</code>,
- <code class="constant">GL_RGB5</code>,
- <code class="constant">GL_RGB8</code>,
- <code class="constant">GL_RGB10</code>,
- <code class="constant">GL_RGB12</code>,
- <code class="constant">GL_RGB16</code>,
- <code class="constant">GL_RGBA</code>,
- <code class="constant">GL_RGBA2</code>,
- <code class="constant">GL_RGBA4</code>,
- <code class="constant">GL_RGB5_A1</code>,
- <code class="constant">GL_RGBA8</code>,
- <code class="constant">GL_RGB10_A2</code>,
- <code class="constant">GL_RGBA12</code>, or
- <code class="constant">GL_RGBA16</code>.
- </p></dd><dt><span class="term"><em class="parameter"><code>sink</code></em></span></dt><dd><p>
- If <code class="constant">GL_TRUE</code>, pixels will be consumed by the minmax
- process and no drawing or texture loading will take place.
- If <code class="constant">GL_FALSE</code>, pixels will proceed to the final conversion process after
- minmax.
- </p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p>
- When <code class="constant">GL_MINMAX</code> is enabled, the RGBA components of incoming pixels are
- compared to the minimum and maximum values for each component, which are
- stored in the two-element minmax table.
- (The first element stores the minima, and the second element stores
- the maxima.)
- If a pixel component is greater than the corresponding component
- in the maximum element, then the maximum element is updated with the
- pixel component value.
- If a pixel component is less than the corresponding component in
- the minimum element, then the minimum element is updated with the
- pixel component value.
- (In both cases, if the internal format of the minmax table includes
- luminance, then the R color component of incoming pixels is used
- for comparison.)
- The contents of the minmax table may be retrieved at a later time
- by calling <a class="citerefentry" href="glGetMinmax.xml"><span class="citerefentry"><span class="refentrytitle">glGetMinmax</span></span></a>.
- 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
- <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>.
- </p><p>
- <code class="function">glMinmax</code> redefines the current minmax table to have entries of the format
- specified by <em class="parameter"><code>internalformat</code></em>.
- The maximum element is initialized with the smallest possible component
- values, and the minimum element is initialized with the largest possible
- component values.
- The values in the previous minmax table, if any, are lost.
- If <em class="parameter"><code>sink</code></em> is <code class="constant">GL_TRUE</code>, then pixels are discarded after minmax;
- no further processing of the pixels takes place, and no drawing,
- texture loading, or pixel readback will result.
- </p><p>
- </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="notes"></a><h2>Notes</h2><p>
- <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>
- is called with an argument of <code class="constant">GL_EXTENSIONS</code>.
- </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="errors"></a><h2>Errors</h2><p>
- <code class="constant">GL_INVALID_ENUM</code> is generated if <em class="parameter"><code>target</code></em> is not one of the allowable
- values.
- </p><p>
- <code class="constant">GL_INVALID_ENUM</code> is generated if <em class="parameter"><code>internalformat</code></em> is not one of the
- allowable values.
- </p><p>
- <code class="constant">GL_INVALID_OPERATION</code> is generated if <code class="function">glMinmax</code> is executed
- between the 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>.
- </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="associatedgets"></a><h2>Associated Gets</h2><p>
- <a class="citerefentry" href="glGetMinmaxParameter.xml"><span class="citerefentry"><span class="refentrytitle">glGetMinmaxParameter</span></span></a>
- </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p>
- <a class="citerefentry" href="glGetMinmax.xml"><span class="citerefentry"><span class="refentrytitle">glGetMinmax</span></span></a>,
- <a class="citerefentry" href="glResetMinmax.xml"><span class="citerefentry"><span class="refentrytitle">glResetMinmax</span></span></a>
- </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="Copyright"></a><h2>Copyright</h2><p>
- Copyright <span class="trademark"></span>© 1991-2006
- Silicon Graphics, Inc. This document is licensed under the SGI
- Free Software B License. For details, see
- <a class="ulink" href="http://oss.sgi.com/projects/FreeB/" target="_top">http://oss.sgi.com/projects/FreeB/</a>.
- </p></div></div></body></html>
HCoop / clinton / guile-figl.git / blobdiff