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><head><title>glGetMap</title><link rel="stylesheet" href="style.css" type="text/css"/><meta name="generator" content="DocBook XSL Stylesheets V1.59.1"/><link rel="home" href="index.xml" title="PyOpenGL 2.0.1.07 Man Pages"/><link rel="up" href="reference-GL.xml" title="GL"/><link rel="previous" href="glGetLight.3G.xml" title="glGetLight"/><link rel="next" href="glGetMaterial.3G.xml" title="glGetMaterial"/></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">glGetMap</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="glGetLight.3G.xml">Prev</a> </td><th width="60%" align="center">GL</th><td width="20%" align="right"> <a accesskey="n" href="glGetMaterial.3G.xml">Next</a></td></tr></table><hr/></div><div class="refentry" lang="en"><a name="glGetMap.3G"/><div class="titlepage"/><div class="refnamediv"><a name="glGetMap.3G-name"/><h2>Name</h2><p>glGetMapdv, glGetMapfv, glGetMapiv &#8212; return evaluator parameters</p></div><div class="refsynopsisdiv"><a name="glGetMap.3G-c_spec"/><h2>C Specification</h2><table class="funcprototype" border="0" cellpadding="0" cellspacing="0"><tr><td valign="top"><code>void <tt>glGetMapdv</tt></code></td><td valign="top"><code>(</code></td><td valign="top"><code>GLenum <i><tt>target</tt></i>, GLenum <i><tt>query</tt></i>, GLdouble *<i><tt>v</tt></i>);</code></td></tr><tr><td valign="top"><code>void <tt>glGetMapfv</tt></code></td><td valign="top"><code>(</code></td><td valign="top"><code>GLenum <i><tt>target</tt></i>, GLenum <i><tt>query</tt></i>, GLfloat *<i><tt>v</tt></i>);</code></td></tr><tr><td valign="top"><code>void <tt>glGetMapiv</tt></code></td><td valign="top"><code>(</code></td><td valign="top"><code>GLenum <i><tt>target</tt></i>, GLenum <i><tt>query</tt></i>, GLint *<i><tt>v</tt></i>);</code></td></tr></table></div><div class="refsynopsisdiv"><a name="glGetMap.3G-python_spec"/><h2>Python Specification</h2><table class="funcprototype" border="0" cellpadding="0" cellspacing="0"><tr><td valign="top"><code><tt>glGetMapdv</tt></code></td><td valign="top"><code>(</code></td><td valign="top"><code><i><tt>target</tt></i>, <i><tt>query</tt></i>) &#8594; <i><tt>v</tt></i></code></td></tr><tr><td valign="top"><code><tt>glGetMapfv</tt></code></td><td valign="top"><code>(</code></td><td valign="top"><code><i><tt>target</tt></i>, <i><tt>query</tt></i>) &#8594; <i><tt>v</tt></i></code></td></tr><tr><td valign="top"><code><tt>glGetMapiv</tt></code></td><td valign="top"><code>(</code></td><td valign="top"><code><i><tt>target</tt></i>, <i><tt>query</tt></i>) &#8594; <i><tt>v</tt></i></code></td></tr></table></div><div class="refsect1" lang="en"><a name="glGetMap.3G-parameters"/><h2>Parameters</h2><div class="variablelist"><dl><dt><span class="term"><i><tt>target</tt></i></span></dt><dd>
						Specifies the symbolic name of a map. Accepted values are <tt>GL_MAP1_COLOR_4</tt>,
						<tt>GL_MAP1_INDEX</tt>, <tt>GL_MAP1_NORMAL</tt>,
						<tt>GL_MAP1_TEXTURE_COORD_1</tt>, <tt>GL_MAP1_TEXTURE_COORD_2</tt>,
						<tt>GL_MAP1_TEXTURE_COORD_3</tt>, <tt>GL_MAP1_TEXTURE_COORD_4</tt>,
						<tt>GL_MAP1_VERTEX_3</tt>, <tt>GL_MAP1_VERTEX_4</tt>,
						<tt>GL_MAP2_COLOR_4</tt>, <tt>GL_MAP2_INDEX</tt>,
						<tt>GL_MAP2_NORMAL</tt>, <tt>GL_MAP2_TEXTURE_COORD_1</tt>,
						<tt>GL_MAP2_TEXTURE_COORD_2</tt>, <tt>GL_MAP2_TEXTURE_COORD_3</tt>,
						<tt>GL_MAP2_TEXTURE_COORD_4</tt>, <tt>GL_MAP2_VERTEX_3</tt>, and
						<tt>GL_MAP2_VERTEX_4</tt>.
					</dd><dt><span class="term"><i><tt>query</tt></i></span></dt><dd>
						Specifies which parameter to return. Symbolic names <tt>GL_COEFF</tt>,
						<tt>GL_ORDER</tt>, and <tt>GL_DOMAIN</tt> are accepted.
					</dd><dt><span class="term"><i><tt>v</tt></i></span></dt><dd>
						Returns the requested data.
					</dd></dl></div></div><div class="refsect1" lang="en"><a name="glGetMap.3G-description"/><h2>Description</h2><p>
			<tt>glMap1</tt> and <tt>glMap2</tt> define evaluators.
			<tt>glGetMap</tt> returns evaluator parameters. <i><tt>target</tt></i> chooses a
			map, <i><tt>query</tt></i> selects a specific parameter, and <i><tt>v</tt></i> points to storage where
			the values will be returned.
		</p><p>
			The acceptable values for the <i><tt>target</tt></i> parameter are described in the <tt>glMap1</tt> and <tt>glMap2</tt> reference pages.
		</p><p>
			<i><tt>query</tt></i> can assume the following values:
		</p><div class="variablelist"><dl><dt><span class="term"><tt>GL_COEFF</tt></span></dt><dd>
						<i><tt>v</tt></i> returns the control points for the evaluator function. One-dimensional evaluators
						return <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
								<mml:mi>order</mml:mi>
							</mml:math> control points, and two-dimensional evaluators return <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
								<mml:mrow>
									<mml:mi>uorder</mml:mi>
									<mml:mo>×</mml:mo>
									<mml:mi>vorder</mml:mi>
								</mml:mrow>
							</mml:math> control points. Each control point consists of one, two, three, or four integer,
						single-precision floating-point, or double-precision floating-point values, depending on the type of the
						evaluator. The GL returns two-dimensional control points in row-major order, incrementing the
						<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
								<mml:mi>uorder</mml:mi>
							</mml:math> index quickly and the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
								<mml:mi>vorder</mml:mi>
							</mml:math> index after each row. Integer values, when requested, are computed by rounding the
						internal floating-point values to the nearest integer values.
					</dd><dt><span class="term"><tt>GL_ORDER</tt></span></dt><dd>
						<i><tt>v</tt></i> returns the order of the evaluator function. One-dimensional evaluators return a
						single value, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
								<mml:mi>order</mml:mi>
							</mml:math>. The initial value is 1. Two-dimensional evaluators return two values, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
								<mml:mi>uorder</mml:mi>
							</mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
								<mml:mi>vorder</mml:mi>
							</mml:math>. The initial value is 1,1.
					</dd><dt><span class="term"><tt>GL_DOMAIN</tt></span></dt><dd>
						<i><tt>v</tt></i> returns the linear <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
								<mml:mi>u</mml:mi>
							</mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
								<mml:mi>v</mml:mi>
							</mml:math> mapping parameters. One-dimensional evaluators return two values, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
								<mml:mi>u1</mml:mi>
							</mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
								<mml:mi>u2</mml:mi>
							</mml:math>, as specified by <tt>glMap1</tt>. Two-dimensional
						evaluators return four values (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
								<mml:mi>u1</mml:mi>
							</mml:math>, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
								<mml:mi>u2</mml:mi>
							</mml:math>, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
								<mml:mi>v1</mml:mi>
							</mml:math>, and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
								<mml:mi>v2</mml:mi>
							</mml:math>) as specified by <tt>glMap2</tt>. Integer values, when
						requested, are computed by rounding the internal floating-point values to the nearest integer values.
					</dd></dl></div></div><div class="refsect1" lang="en"><a name="glGetMap.3G-notes"/><h2>Notes</h2><p>
			If an error is generated, no change is made to the contents of <i><tt>v</tt></i>.
		</p></div><div class="refsect1" lang="en"><a name="glGetMap.3G-errors"/><h2>Errors</h2><p>
			<tt>GL_INVALID_ENUM</tt> is generated if either <i><tt>target</tt></i> or
			<i><tt>query</tt></i> is not an accepted value.
		</p><p>
			<tt>GL_INVALID_OPERATION</tt> is generated if <tt>glGetMap</tt> is executed
			between the execution of <a href="glBegin.3G.xml"><tt>glBegin</tt></a> and the corresponding execution of <a href="glBegin.3G.xml"><tt>glEnd</tt></a>.
		</p></div><div class="refsect1" lang="en"><a name="glGetMap.3G-see_also"/><h2>See Also</h2><p>
			<span class="simplelist"><a href="glEvalCoord.3G.xml">glEvalCoord</a>, <a href="glMap1.3G.xml">glMap1</a>, <a href="glMap2.3G.xml">glMap2</a></span>
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