--- /dev/null
+<?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" /><title>glTexGen</title><meta name="generator" content="DocBook XSL Stylesheets V1.69.1" /></head><body><div class="refentry" lang="en" xml:lang="en"><a id="glTexGen"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glTexGen — control the generation of texture coordinates</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">glTexGeni</b>(</code></td><td>GLenum </td><td><var class="pdparam">coord</var>, </td></tr><tr><td> </td><td>GLenum </td><td><var class="pdparam">pname</var>, </td></tr><tr><td> </td><td>GLint </td><td><var class="pdparam">param</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">glTexGenf</b>(</code></td><td>GLenum </td><td><var class="pdparam">coord</var>, </td></tr><tr><td> </td><td>GLenum </td><td><var class="pdparam">pname</var>, </td></tr><tr><td> </td><td>GLfloat </td><td><var class="pdparam">param</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">glTexGend</b>(</code></td><td>GLenum </td><td><var class="pdparam">coord</var>, </td></tr><tr><td> </td><td>GLenum </td><td><var class="pdparam">pname</var>, </td></tr><tr><td> </td><td>GLdouble </td><td><var class="pdparam">param</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>coord</code></em></span></dt><dd><p>
+ Specifies a texture coordinate.
+ Must be one of <code class="constant">GL_S</code>, <code class="constant">GL_T</code>, <code class="constant">GL_R</code>, or <code class="constant">GL_Q</code>.
+ </p></dd><dt><span class="term"><em class="parameter"><code>pname</code></em></span></dt><dd><p>
+ Specifies the symbolic name of the texture-coordinate generation function.
+ Must be <code class="constant">GL_TEXTURE_GEN_MODE</code>.
+ </p></dd><dt><span class="term"><em class="parameter"><code>param</code></em></span></dt><dd><p>
+ Specifies a single-valued texture generation parameter,
+ one of <code class="constant">GL_OBJECT_LINEAR</code>, <code class="constant">GL_EYE_LINEAR</code>, <code class="constant">GL_SPHERE_MAP</code>,
+ <code class="constant">GL_NORMAL_MAP</code>, or <code class="constant">GL_REFLECTION_MAP</code>.
+ </p></dd></dl></div></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">glTexGeniv</b>(</code></td><td>GLenum </td><td><var class="pdparam">coord</var>, </td></tr><tr><td> </td><td>GLenum </td><td><var class="pdparam">pname</var>, </td></tr><tr><td> </td><td>const GLint * </td><td><var class="pdparam">params</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">glTexGenfv</b>(</code></td><td>GLenum </td><td><var class="pdparam">coord</var>, </td></tr><tr><td> </td><td>GLenum </td><td><var class="pdparam">pname</var>, </td></tr><tr><td> </td><td>const GLfloat * </td><td><var class="pdparam">params</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">glTexGendv</b>(</code></td><td>GLenum </td><td><var class="pdparam">coord</var>, </td></tr><tr><td> </td><td>GLenum </td><td><var class="pdparam">pname</var>, </td></tr><tr><td> </td><td>const GLdouble * </td><td><var class="pdparam">params</var><code>)</code>;</td></tr></table></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="parameters2"></a><h2>Parameters</h2><div class="variablelist"><dl><dt><span class="term"><em class="parameter"><code>coord</code></em></span></dt><dd><p>
+ Specifies a texture coordinate.
+ Must be one of <code class="constant">GL_S</code>, <code class="constant">GL_T</code>, <code class="constant">GL_R</code>, or <code class="constant">GL_Q</code>.
+ </p></dd><dt><span class="term"><em class="parameter"><code>pname</code></em></span></dt><dd><p>
+ Specifies the symbolic name of the texture-coordinate generation function
+ or function parameters.
+ Must be
+ <code class="constant">GL_TEXTURE_GEN_MODE</code>,
+ <code class="constant">GL_OBJECT_PLANE</code>, or
+ <code class="constant">GL_EYE_PLANE</code>.
+ </p></dd><dt><span class="term"><em class="parameter"><code>params</code></em></span></dt><dd><p>
+ Specifies a pointer to an array of texture generation parameters.
+ If <em class="parameter"><code>pname</code></em> is <code class="constant">GL_TEXTURE_GEN_MODE</code>,
+ then the array must contain a single symbolic constant,
+ one of
+ <code class="constant">GL_OBJECT_LINEAR</code>,
+ <code class="constant">GL_EYE_LINEAR</code>,
+ <code class="constant">GL_SPHERE_MAP</code>,
+ <code class="constant">GL_NORMAL_MAP</code>, or
+ <code class="constant">GL_REFLECTION_MAP</code>.
+ Otherwise,
+ <em class="parameter"><code>params</code></em> holds the coefficients for the texture-coordinate generation function
+ specified 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">glTexGen</code> selects a texture-coordinate generation function
+ or supplies coefficients for one of the functions.
+ <em class="parameter"><code>coord</code></em> names one of the (<span class="emphasis"><em>s</em></span>, <span class="emphasis"><em>t</em></span>, <span class="emphasis"><em>r</em></span>, <span class="emphasis"><em>q</em></span>) texture
+ coordinates; it must be one of the symbols
+ <code class="constant">GL_S</code>,
+ <code class="constant">GL_T</code>,
+ <code class="constant">GL_R</code>, or
+ <code class="constant">GL_Q</code>.
+ <em class="parameter"><code>pname</code></em> must be one of three symbolic constants:
+ <code class="constant">GL_TEXTURE_GEN_MODE</code>,
+ <code class="constant">GL_OBJECT_PLANE</code>, or
+ <code class="constant">GL_EYE_PLANE</code>.
+ If <em class="parameter"><code>pname</code></em> is <code class="constant">GL_TEXTURE_GEN_MODE</code>,
+ then <em class="parameter"><code>params</code></em> chooses a mode,
+ one of
+ <code class="constant">GL_OBJECT_LINEAR</code>,
+ <code class="constant">GL_EYE_LINEAR</code>,
+ <code class="constant">GL_SPHERE_MAP</code>,
+ <code class="constant">GL_NORMAL_MAP</code>, or
+ <code class="constant">GL_REFLECTION_MAP</code>.
+ If <em class="parameter"><code>pname</code></em> is either <code class="constant">GL_OBJECT_PLANE</code> or <code class="constant">GL_EYE_PLANE</code>,
+ <em class="parameter"><code>params</code></em> contains coefficients for the corresponding
+ texture generation function.
+ </p><p>
+ If the texture generation function is <code class="constant">GL_OBJECT_LINEAR</code>,
+ the function
+ </p><p>
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:mi mathvariant="italic">g</mml:mi>
+ <mml:mo>=</mml:mo>
+ <mml:mrow>
+ <mml:mrow>
+ <mml:msub><mml:mi mathvariant="italic">p</mml:mi>
+ <mml:mn>1</mml:mn>
+ </mml:msub>
+ <mml:mo>×</mml:mo>
+ <mml:msub><mml:mi mathvariant="italic">x</mml:mi>
+ <mml:mi mathvariant="italic">o</mml:mi>
+ </mml:msub>
+ </mml:mrow>
+ <mml:mo>+</mml:mo>
+ <mml:mrow>
+ <mml:msub><mml:mi mathvariant="italic">p</mml:mi>
+ <mml:mn>2</mml:mn>
+ </mml:msub>
+ <mml:mo>×</mml:mo>
+ <mml:msub><mml:mi mathvariant="italic">y</mml:mi>
+ <mml:mi mathvariant="italic">o</mml:mi>
+ </mml:msub>
+ </mml:mrow>
+ <mml:mo>+</mml:mo>
+ <mml:mrow>
+ <mml:msub><mml:mi mathvariant="italic">p</mml:mi>
+ <mml:mn>3</mml:mn>
+ </mml:msub>
+ <mml:mo>×</mml:mo>
+ <mml:msub><mml:mi mathvariant="italic">z</mml:mi>
+ <mml:mi mathvariant="italic">o</mml:mi>
+ </mml:msub>
+ </mml:mrow>
+ <mml:mo>+</mml:mo>
+ <mml:mrow>
+ <mml:msub><mml:mi mathvariant="italic">p</mml:mi>
+ <mml:mn>4</mml:mn>
+ </mml:msub>
+ <mml:mo>×</mml:mo>
+ <mml:msub><mml:mi mathvariant="italic">w</mml:mi>
+ <mml:mi mathvariant="italic">o</mml:mi>
+ </mml:msub>
+ </mml:mrow>
+ </mml:mrow>
+ </mml:mrow>
+ </mml:math>
+ </p><p>
+ is used, where
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">g</mml:mi></mml:math>
+ is the value computed for the coordinate named in <em class="parameter"><code>coord</code></em>,
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:msub><mml:mi mathvariant="italic">p</mml:mi>
+ <mml:mn>1</mml:mn>
+ </mml:msub>
+ </mml:math>,
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:msub><mml:mi mathvariant="italic">p</mml:mi>
+ <mml:mn>2</mml:mn>
+ </mml:msub>
+ </mml:math>,
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:msub><mml:mi mathvariant="italic">p</mml:mi>
+ <mml:mn>3</mml:mn>
+ </mml:msub>
+ </mml:math>,
+ and
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:msub><mml:mi mathvariant="italic">p</mml:mi>
+ <mml:mn>4</mml:mn>
+ </mml:msub>
+ </mml:math>
+ are the four values supplied in <em class="parameter"><code>params</code></em>, and
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:msub><mml:mi mathvariant="italic">x</mml:mi>
+ <mml:mi mathvariant="italic">o</mml:mi>
+ </mml:msub>
+ </mml:math>,
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:msub><mml:mi mathvariant="italic">y</mml:mi>
+ <mml:mi mathvariant="italic">o</mml:mi>
+ </mml:msub>
+ </mml:math>,
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:msub><mml:mi mathvariant="italic">z</mml:mi>
+ <mml:mi mathvariant="italic">o</mml:mi>
+ </mml:msub>
+ </mml:math>,
+ and
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:msub><mml:mi mathvariant="italic">w</mml:mi>
+ <mml:mi mathvariant="italic">o</mml:mi>
+ </mml:msub>
+ </mml:math>
+ are the object coordinates of the vertex.
+ This function can be used, for example, to texture-map terrain using sea level
+ as a reference plane
+ (defined by
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:msub><mml:mi mathvariant="italic">p</mml:mi>
+ <mml:mn>1</mml:mn>
+ </mml:msub>
+ </mml:math>,
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:msub><mml:mi mathvariant="italic">p</mml:mi>
+ <mml:mn>2</mml:mn>
+ </mml:msub>
+ </mml:math>,
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:msub><mml:mi mathvariant="italic">p</mml:mi>
+ <mml:mn>3</mml:mn>
+ </mml:msub>
+ </mml:math>,
+ and
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:msub><mml:mi mathvariant="italic">p</mml:mi>
+ <mml:mn>4</mml:mn>
+ </mml:msub>
+ </mml:math>).
+ The altitude of a terrain vertex is computed by the <code class="constant">GL_OBJECT_LINEAR</code>
+ coordinate generation function as its distance from sea level;
+ that altitude can then be used to index the texture image to map white snow
+ onto peaks and green grass onto foothills.
+ </p><p>
+ If the texture generation function is <code class="constant">GL_EYE_LINEAR</code>, the function
+ </p><p>
+ </p><div class="informalequation"><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:mi mathvariant="italic">g</mml:mi>
+ <mml:mo>=</mml:mo>
+ <mml:mrow>
+ <mml:mrow>
+ <mml:msup><mml:mfenced open="" close="">
+ <mml:msub><mml:mi mathvariant="italic">p</mml:mi>
+ <mml:mn>1</mml:mn>
+ </mml:msub>
+ </mml:mfenced>
+ <mml:mo>″</mml:mo>
+ </mml:msup>
+ <mml:mo>×</mml:mo>
+ <mml:msub><mml:mi mathvariant="italic">x</mml:mi>
+ <mml:mi mathvariant="italic">e</mml:mi>
+ </mml:msub>
+ </mml:mrow>
+ <mml:mo>+</mml:mo>
+ <mml:mrow>
+ <mml:msup><mml:mfenced open="" close="">
+ <mml:msub><mml:mi mathvariant="italic">p</mml:mi>
+ <mml:mn>2</mml:mn>
+ </mml:msub>
+ </mml:mfenced>
+ <mml:mo>″</mml:mo>
+ </mml:msup>
+ <mml:mo>×</mml:mo>
+ <mml:msub><mml:mi mathvariant="italic">y</mml:mi>
+ <mml:mi mathvariant="italic">e</mml:mi>
+ </mml:msub>
+ </mml:mrow>
+ <mml:mo>+</mml:mo>
+ <mml:mrow>
+ <mml:msup><mml:mfenced open="" close="">
+ <mml:msub><mml:mi mathvariant="italic">p</mml:mi>
+ <mml:mn>3</mml:mn>
+ </mml:msub>
+ </mml:mfenced>
+ <mml:mo>″</mml:mo>
+ </mml:msup>
+ <mml:mo>×</mml:mo>
+ <mml:msub><mml:mi mathvariant="italic">z</mml:mi>
+ <mml:mi mathvariant="italic">e</mml:mi>
+ </mml:msub>
+ </mml:mrow>
+ <mml:mo>+</mml:mo>
+ <mml:mrow>
+ <mml:msup><mml:mfenced open="" close="">
+ <mml:msub><mml:mi mathvariant="italic">p</mml:mi>
+ <mml:mn>4</mml:mn>
+ </mml:msub>
+ </mml:mfenced>
+ <mml:mo>″</mml:mo>
+ </mml:msup>
+ <mml:mo>×</mml:mo>
+ <mml:msub><mml:mi mathvariant="italic">w</mml:mi>
+ <mml:mi mathvariant="italic">e</mml:mi>
+ </mml:msub>
+ </mml:mrow>
+ </mml:mrow>
+ </mml:mrow>
+ </mml:math></div><p>
+ </p><p>
+ is used, where
+ </p><p>
+ </p><div class="informalequation"><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:mfenced open="(" close=")">
+ <mml:mrow>
+ <mml:msup><mml:mfenced open="" close="">
+ <mml:msub><mml:mi mathvariant="italic">p</mml:mi>
+ <mml:mn>1</mml:mn>
+ </mml:msub>
+ </mml:mfenced>
+ <mml:mo>″</mml:mo>
+ </mml:msup>
+ <mml:mo></mml:mo>
+ <mml:msup><mml:mfenced open="" close="">
+ <mml:msub><mml:mi mathvariant="italic">p</mml:mi>
+ <mml:mn>2</mml:mn>
+ </mml:msub>
+ </mml:mfenced>
+ <mml:mo>″</mml:mo>
+ </mml:msup>
+ <mml:mo></mml:mo>
+ <mml:msup><mml:mfenced open="" close="">
+ <mml:msub><mml:mi mathvariant="italic">p</mml:mi>
+ <mml:mn>3</mml:mn>
+ </mml:msub>
+ </mml:mfenced>
+ <mml:mo>″</mml:mo>
+ </mml:msup>
+ <mml:mo></mml:mo>
+ <mml:msup><mml:mfenced open="" close="">
+ <mml:msub><mml:mi mathvariant="italic">p</mml:mi>
+ <mml:mn>4</mml:mn>
+ </mml:msub>
+ </mml:mfenced>
+ <mml:mo>″</mml:mo>
+ </mml:msup>
+ </mml:mrow>
+ </mml:mfenced>
+ <mml:mo>=</mml:mo>
+ <mml:mrow>
+ <mml:mfenced open="(" close=")">
+ <mml:mrow>
+ <mml:msub><mml:mi mathvariant="italic">p</mml:mi>
+ <mml:mn>1</mml:mn>
+ </mml:msub>
+ <mml:mo></mml:mo>
+ <mml:msub><mml:mi mathvariant="italic">p</mml:mi>
+ <mml:mn>2</mml:mn>
+ </mml:msub>
+ <mml:mo></mml:mo>
+ <mml:msub><mml:mi mathvariant="italic">p</mml:mi>
+ <mml:mn>3</mml:mn>
+ </mml:msub>
+ <mml:mo></mml:mo>
+ <mml:msub><mml:mi mathvariant="italic">p</mml:mi>
+ <mml:mn>4</mml:mn>
+ </mml:msub>
+ </mml:mrow>
+ </mml:mfenced>
+ <mml:mo></mml:mo>
+ <mml:msup><mml:mi mathvariant="italic">M</mml:mi>
+ <mml:mn>-1</mml:mn>
+ </mml:msup>
+ </mml:mrow>
+ </mml:mrow>
+ </mml:math></div><p>
+ </p><p>
+ and
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:msub><mml:mi mathvariant="italic">x</mml:mi>
+ <mml:mi mathvariant="italic">e</mml:mi>
+ </mml:msub>
+ </mml:math>,
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:msub><mml:mi mathvariant="italic">y</mml:mi>
+ <mml:mi mathvariant="italic">e</mml:mi>
+ </mml:msub>
+ </mml:math>,
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:msub><mml:mi mathvariant="italic">z</mml:mi>
+ <mml:mi mathvariant="italic">e</mml:mi>
+ </mml:msub>
+ </mml:math>,
+ and
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:msub><mml:mi mathvariant="italic">w</mml:mi>
+ <mml:mi mathvariant="italic">e</mml:mi>
+ </mml:msub>
+ </mml:math>
+ are the eye coordinates of the vertex,
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:msub><mml:mi mathvariant="italic">p</mml:mi>
+ <mml:mn>1</mml:mn>
+ </mml:msub>
+ </mml:math>,
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:msub><mml:mi mathvariant="italic">p</mml:mi>
+ <mml:mn>2</mml:mn>
+ </mml:msub>
+ </mml:math>,
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:msub><mml:mi mathvariant="italic">p</mml:mi>
+ <mml:mn>3</mml:mn>
+ </mml:msub>
+ </mml:math>,
+ and
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:msub><mml:mi mathvariant="italic">p</mml:mi>
+ <mml:mn>4</mml:mn>
+ </mml:msub>
+ </mml:math>
+ are the values supplied in <em class="parameter"><code>params</code></em>, and
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">M</mml:mi></mml:math>
+ is the modelview matrix when <code class="function">glTexGen</code> is invoked.
+ If
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">M</mml:mi></mml:math>
+ is poorly conditioned or singular,
+ texture coordinates generated by the resulting function may be inaccurate
+ or undefined.
+ </p><p>
+ Note that the values in <em class="parameter"><code>params</code></em> define a reference plane in eye coordinates.
+ The modelview matrix that is applied to them may not be the same one
+ in effect when the polygon vertices are transformed.
+ This function establishes a field of texture coordinates
+ that can produce dynamic contour lines on moving objects.
+ </p><p>
+ If the texture generation function is <code class="constant">GL_SPHERE_MAP</code> and <em class="parameter"><code>coord</code></em> is either
+ <code class="constant">GL_S</code> or
+ <code class="constant">GL_T</code>,
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">s</mml:mi></mml:math>
+ and
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">t</mml:mi></mml:math>
+ texture coordinates are generated as follows.
+ Let <span class="emphasis"><em>u</em></span> be the unit vector pointing from the origin to the polygon vertex
+ (in eye coordinates).
+ Let <span class="emphasis"><em>n</em></span> sup prime be the current normal,
+ after transformation to eye coordinates.
+ Let
+ </p><p>
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:mi mathvariant="italic">f</mml:mi>
+ <mml:mo>=</mml:mo>
+ <mml:msup><mml:mfenced open="(" close=")">
+ <mml:mrow>
+ <mml:msub><mml:mi mathvariant="italic">f</mml:mi>
+ <mml:mi mathvariant="italic">x</mml:mi>
+ </mml:msub>
+ <mml:mo></mml:mo>
+ <mml:msub><mml:mi mathvariant="italic">f</mml:mi>
+ <mml:mi mathvariant="italic">y</mml:mi>
+ </mml:msub>
+ <mml:mo></mml:mo>
+ <mml:msub><mml:mi mathvariant="italic">f</mml:mi>
+ <mml:mi mathvariant="italic">z</mml:mi>
+ </mml:msub>
+ </mml:mrow>
+ </mml:mfenced>
+ <mml:mi mathvariant="italic">T</mml:mi>
+ </mml:msup>
+ </mml:mrow>
+ </mml:math>
+ be the reflection vector such that
+ </p><p>
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:mi mathvariant="italic">f</mml:mi>
+ <mml:mo>=</mml:mo>
+ <mml:mrow>
+ <mml:mi mathvariant="italic">u</mml:mi>
+ <mml:mo>-</mml:mo>
+ <mml:mn>2</mml:mn>
+ <mml:mo></mml:mo>
+ <mml:msup><mml:mi mathvariant="italic">n</mml:mi>
+ <mml:mo>″</mml:mo>
+ </mml:msup>
+ <mml:mo></mml:mo>
+ <mml:msup><mml:mfenced open="" close="">
+ <mml:msup><mml:mi mathvariant="italic">n</mml:mi>
+ <mml:mo>″</mml:mo>
+ </mml:msup>
+ </mml:mfenced>
+ <mml:mi mathvariant="italic">T</mml:mi>
+ </mml:msup>
+ <mml:mo></mml:mo>
+ <mml:mi mathvariant="italic">u</mml:mi>
+ </mml:mrow>
+ </mml:mrow>
+ </mml:math>
+ </p><p>
+ Finally, let
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:mi mathvariant="italic">m</mml:mi>
+ <mml:mo>=</mml:mo>
+ <mml:mrow>
+ <mml:mn>2</mml:mn>
+ <mml:mo></mml:mo>
+ <mml:msqrt>
+ <mml:mfenced open="(" close=")">
+ <mml:mrow>
+ <mml:msup><mml:mfenced open="" close="">
+ <mml:msub><mml:mi mathvariant="italic">f</mml:mi>
+ <mml:mi mathvariant="italic">x</mml:mi>
+ </mml:msub>
+ </mml:mfenced>
+ <mml:mn>2</mml:mn>
+ </mml:msup>
+ <mml:mo>+</mml:mo>
+ <mml:msup><mml:mfenced open="" close="">
+ <mml:msub><mml:mi mathvariant="italic">f</mml:mi>
+ <mml:mi mathvariant="italic">y</mml:mi>
+ </mml:msub>
+ </mml:mfenced>
+ <mml:mn>2</mml:mn>
+ </mml:msup>
+ <mml:mo>+</mml:mo>
+ <mml:msup><mml:mfenced open="(" close=")">
+ <mml:mrow>
+ <mml:msub><mml:mi mathvariant="italic">f</mml:mi>
+ <mml:mi mathvariant="italic">z</mml:mi>
+ </mml:msub>
+ <mml:mo>+</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:mfenced>
+ <mml:mn>2</mml:mn>
+ </mml:msup>
+ </mml:mrow>
+ </mml:mfenced>
+ </mml:msqrt>
+ </mml:mrow>
+ </mml:mrow>
+ </mml:math>.
+ Then the values assigned to the
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">s</mml:mi></mml:math>
+ and
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">t</mml:mi></mml:math>
+ texture coordinates are
+ </p><p>
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:mi mathvariant="italic">s</mml:mi>
+ <mml:mo>=</mml:mo>
+ <mml:mrow>
+ <mml:mfrac>
+ <mml:msub><mml:mi mathvariant="italic">f</mml:mi>
+ <mml:mi mathvariant="italic">x</mml:mi>
+ </mml:msub>
+ <mml:mi mathvariant="italic">m</mml:mi>
+ </mml:mfrac>
+ <mml:mo>+</mml:mo>
+ <mml:mfrac>
+ <mml:mn>1</mml:mn>
+ <mml:mn>2</mml:mn>
+ </mml:mfrac>
+ </mml:mrow>
+ </mml:mrow>
+ </mml:math>
+ </p><p>
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:mi mathvariant="italic">t</mml:mi>
+ <mml:mo>=</mml:mo>
+ <mml:mrow>
+ <mml:mfrac>
+ <mml:msub><mml:mi mathvariant="italic">f</mml:mi>
+ <mml:mi mathvariant="italic">y</mml:mi>
+ </mml:msub>
+ <mml:mi mathvariant="italic">m</mml:mi>
+ </mml:mfrac>
+ <mml:mo>+</mml:mo>
+ <mml:mfrac>
+ <mml:mn>1</mml:mn>
+ <mml:mn>2</mml:mn>
+ </mml:mfrac>
+ </mml:mrow>
+ </mml:mrow>
+ </mml:math>
+ </p><p>
+ To enable or disable a texture-coordinate generation function, call
+ <a href="glEnable.xml"><span class="citerefentry"><span class="refentrytitle">glEnable</span></span></a> or <a href="glDisable.xml"><span class="citerefentry"><span class="refentrytitle">glDisable</span></span></a>
+ with one of the symbolic texture-coordinate names
+ (<code class="constant">GL_TEXTURE_GEN_S</code>,
+ <code class="constant">GL_TEXTURE_GEN_T</code>,
+ <code class="constant">GL_TEXTURE_GEN_R</code>, or
+ <code class="constant">GL_TEXTURE_GEN_Q</code>) as the argument.
+ When enabled,
+ the specified texture coordinate is computed
+ according to the generating function associated with that coordinate.
+ When disabled,
+ subsequent vertices take the specified texture coordinate
+ from the current set of texture coordinates. Initially, all texture
+ generation functions are set to <code class="constant">GL_EYE_LINEAR</code> and are disabled.
+ Both
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">s</mml:mi></mml:math>
+ plane equations are (1, 0, 0, 0),
+ both
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">t</mml:mi></mml:math>
+ plane equations are (0, 1, 0, 0),
+ and all
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">r</mml:mi></mml:math>
+ and
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">q</mml:mi></mml:math>
+ plane equations are (0, 0, 0, 0).
+ </p><p>
+ When the <code class="code">ARB_multitexture</code> extension is supported, <code class="function">glTexGen</code> sets the
+ texture generation parameters for the currently active texture unit,
+ selected with <a href="glActiveTexture.xml"><span class="citerefentry"><span class="refentrytitle">glActiveTexture</span></span></a>.
+ </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 when <em class="parameter"><code>coord</code></em> or <em class="parameter"><code>pname</code></em> is not an
+ accepted defined value,
+ or when <em class="parameter"><code>pname</code></em> is <code class="constant">GL_TEXTURE_GEN_MODE</code> and <em class="parameter"><code>params</code></em> is not an
+ accepted defined value.
+ </p><p>
+ <code class="constant">GL_INVALID_ENUM</code> is generated when <em class="parameter"><code>pname</code></em> is <code class="constant">GL_TEXTURE_GEN_MODE</code>,
+ <em class="parameter"><code>params</code></em> is <code class="constant">GL_SPHERE_MAP</code>,
+ and <em class="parameter"><code>coord</code></em> is either <code class="constant">GL_R</code> or <code class="constant">GL_Q</code>.
+ </p><p>
+ <code class="constant">GL_INVALID_OPERATION</code> is generated if <code class="function">glTexGen</code>
+ is executed between the execution of <a href="glBegin.xml"><span class="citerefentry"><span class="refentrytitle">glBegin</span></span></a>
+ and the corresponding execution of <a 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 href="glGetTexGen.xml"><span class="citerefentry"><span class="refentrytitle">glGetTexGen</span></span></a>
+ </p><p>
+ <a href="glIsEnabled.xml"><span class="citerefentry"><span class="refentrytitle">glIsEnabled</span></span></a> with argument <code class="constant">GL_TEXTURE_GEN_S</code>
+ </p><p>
+ <a href="glIsEnabled.xml"><span class="citerefentry"><span class="refentrytitle">glIsEnabled</span></span></a> with argument <code class="constant">GL_TEXTURE_GEN_T</code>
+ </p><p>
+ <a href="glIsEnabled.xml"><span class="citerefentry"><span class="refentrytitle">glIsEnabled</span></span></a> with argument <code class="constant">GL_TEXTURE_GEN_R</code>
+ </p><p>
+ <a href="glIsEnabled.xml"><span class="citerefentry"><span class="refentrytitle">glIsEnabled</span></span></a> with argument <code class="constant">GL_TEXTURE_GEN_Q</code>
+ </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p>
+ <a href="glActiveTexture.xml"><span class="citerefentry"><span class="refentrytitle">glActiveTexture</span></span></a>,
+ <a href="glCopyPixels.xml"><span class="citerefentry"><span class="refentrytitle">glCopyPixels</span></span></a>,
+ <a href="glCopyTexImage2D.xml"><span class="citerefentry"><span class="refentrytitle">glCopyTexImage2D</span></span></a>,
+ <a href="glCopyTexSubImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glCopyTexSubImage1D</span></span></a>,
+ <a href="glCopyTexSubImage2D.xml"><span class="citerefentry"><span class="refentrytitle">glCopyTexSubImage2D</span></span></a>,
+ <a href="glCopyTexSubImage3D.xml"><span class="citerefentry"><span class="refentrytitle">glCopyTexSubImage3D</span></span></a>,
+ <a href="glTexEnv.xml"><span class="citerefentry"><span class="refentrytitle">glTexEnv</span></span></a>,
+ <a href="glTexImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage1D</span></span></a>,
+ <a href="glTexImage2D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage2D</span></span></a>,
+ <a href="glTexImage3D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage3D</span></span></a>,
+ <a href="glTexParameter.xml"><span class="citerefentry"><span class="refentrytitle">glTexParameter</span></span></a>,
+ <a href="glTexSubImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glTexSubImage1D</span></span></a>,
+ <a href="glTexSubImage2D.xml"><span class="citerefentry"><span class="refentrytitle">glTexSubImage2D</span></span></a>,
+ <a href="glTexSubImage3D.xml"><span class="citerefentry"><span class="refentrytitle">glTexSubImage3D</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 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