<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "xhtml1-transitional.dtd">
<!-- saved from url=(0013)about:internet -->
<?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" /><link rel="stylesheet" type="text/css" href="opengl-man.css" /><title>glPatchParameter - OpenGL 4 Reference Pages</title><meta name="generator" content="DocBook XSL Stylesheets V1.69.1" /></head><body><div class="refentry" lang="en" xml:lang="en"><a id="glPatchParameter"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glPatchParameter — specifies the parameters for patch primitives</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">glPatchParameteri</b>(</code></td><td>GLenum  </td><td><var class="pdparam">pname</var>, </td></tr><tr><td> </td><td>GLint  </td><td><var class="pdparam">value</var><code>)</code>;</td></tr></table></div><div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0"><tr><td><code class="funcdef">void <b class="fsfunc">glPatchParameterfv</b>(</code></td><td>GLenum  </td><td><var class="pdparam">pname</var>, </td></tr><tr><td> </td><td>const GLfloat * </td><td><var class="pdparam">values</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>pname</code></em></span></dt><dd><p>
                    Specifies the name of the parameter to set. The symbolc constants <code class="constant">GL_PATCH_VERTICES</code>,
                    <code class="constant">GL_PATCH_DEFAULT_OUTER_LEVEL</code>, and <code class="constant">GL_PATCH_DEFAULT_INNER_LEVEL</code> are accepted.
                </p></dd><dt><span class="term"><em class="parameter"><code>value</code></em></span></dt><dd><p>
                    Specifies the new value for the parameter given by <em class="parameter"><code>pname</code></em>.
                </p></dd><dt><span class="term"><em class="parameter"><code>values</code></em></span></dt><dd><p>
                    Specifies the address of an array containing the new values for the parameter given by <em class="parameter"><code>pname</code></em>.
                </p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p>
            <code class="function">glPatchParameter</code> specifies the parameters that will be used for patch primitives. <em class="parameter"><code>pname</code></em>
            specifies the parameter to modify and must be either <code class="constant">GL_PATCH_VERTICES</code>, <code class="constant">GL_PATCH_DEFAULT_OUTER_LEVEL</code>
            or <code class="constant">GL_PATCH_DEFAULT_INNER_LEVEL</code>. For <code class="function">glPatchParameteri</code>, <em class="parameter"><code>value</code></em> specifies
            the new value for the parameter specified by <em class="parameter"><code>pname</code></em>. For <code class="function">glPatchParameterfv</code>, <em class="parameter"><code>values</code></em>
            specifies the address of an array containing the new values for the parameter specified by <em class="parameter"><code>pname</code></em>.
        </p><p>
            When <em class="parameter"><code>pname</code></em> is <code class="constant">GL_PATCH_VERTICES</code>, <em class="parameter"><code>value</code></em> specifies the number
            of vertices that will be used to make up a single patch primitive. Patch primitives are consumed by the tessellation control
            shader (if present) and subsequently used for tessellation. When primitives are specified using
            <a href="glDrawArrays.xml"><span class="citerefentry"><span class="refentrytitle">glDrawArrays</span></span></a> or a similar function, each patch will be made
            from <em class="parameter"><code>parameter</code></em> control points, each represented by a vertex taken from the enabeld vertex arrays.
            <em class="parameter"><code>parameter</code></em> must be greater than zero, and less than or equal to the value of <code class="constant">GL_MAX_PATCH_VERTICES</code>.
         </p><p>
            When <em class="parameter"><code>pname</code></em> is <code class="constant">GL_PATCH_DEFAULT_OUTER_LEVEL</code> or <code class="constant">GL_PATCH_DEFAULT_INNER_LEVEL</code>,
            <em class="parameter"><code>values</code></em> contains the address of an array contiaining the default outer or inner tessellation levels, respectively,
            to be used when no tessellation control shader is present.
         </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>pname</code></em> is not an accepted value.
        </p><p>
            <code class="constant">GL_INVALID_VALUE</code> is generated if <em class="parameter"><code>pname</code></em> is <code class="constant">GL_PATCH_VERTICES</code>
            and <em class="parameter"><code>value</code></em> is less than or equal to zero, or greater than the value of <code class="constant">GL_MAX_PATCH_VERTICES</code>.
        </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p>
            <a href="glDrawArrays.xml"><span class="citerefentry"><span class="refentrytitle">glDrawArrays</span></span></a>,
            <a href="glDrawArraysInstanced.xml"><span class="citerefentry"><span class="refentrytitle">glDrawArraysInstanced</span></span></a>,
            <a href="glDrawElements.xml"><span class="citerefentry"><span class="refentrytitle">glDrawElements</span></span></a>,
            <a href="glDrawRangeElements.xml"><span class="citerefentry"><span class="refentrytitle">glDrawRangeElements</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>© 2010 Khronos Group. 
            This material may be distributed subject to the terms and conditions set forth in 
            the Open Publication License, v 1.0, 8 June 1999.
            <a href="http://opencontent.org/openpub/" target="_top">http://opencontent.org/openpub/</a>.
        </p></div></div></body></html>
