--- /dev/null
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN"
+ "http://www.oasis-open.org/docbook/xml/mathml/1.1CR1/dbmathml.dtd">
+<refentry id="glShadeModel">
+ <refmeta>
+ <refmetainfo>
+ <copyright>
+ <year>1991-2006</year>
+ <holder>Silicon Graphics, Inc.</holder>
+ </copyright>
+ </refmetainfo>
+ <refentrytitle>glShadeModel</refentrytitle>
+ <manvolnum>3G</manvolnum>
+ </refmeta>
+ <refnamediv>
+ <refname>glShadeModel</refname>
+ <refpurpose>select flat or smooth shading</refpurpose>
+ </refnamediv>
+ <refsynopsisdiv><title>C Specification</title>
+ <funcsynopsis>
+ <funcprototype>
+ <funcdef>void <function>glShadeModel</function></funcdef>
+ <paramdef>GLenum <parameter>mode</parameter></paramdef>
+ </funcprototype>
+ </funcsynopsis>
+ </refsynopsisdiv>
+ <!-- eqn: ignoring delim $$ -->
+ <refsect1 id="parameters"><title>Parameters</title>
+ <variablelist>
+ <varlistentry>
+ <term><parameter>mode</parameter></term>
+ <listitem>
+ <para>
+ Specifies a symbolic value representing a shading technique.
+ Accepted values are <constant>GL_FLAT</constant> and <constant>GL_SMOOTH</constant>.
+ The initial value is <constant>GL_SMOOTH</constant>.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+ <refsect1 id="description"><title>Description</title>
+ <para>
+ GL primitives can have either flat or smooth shading.
+ Smooth shading,
+ the default,
+ causes the computed colors of vertices to be interpolated as the
+ primitive is rasterized,
+ typically assigning different colors to each resulting pixel fragment.
+ Flat shading selects the computed color of just one vertex
+ and assigns it to all the pixel fragments
+ generated by rasterizing a single primitive.
+ In either case, the computed color of a vertex is the result of
+ lighting if lighting is enabled,
+ or it is the current color at the time the vertex was specified if
+ lighting is disabled.
+ </para>
+ <para>
+ Flat and smooth shading are indistinguishable for points.
+ Starting when <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry> is issued and counting vertices and
+ primitives from 1, the GL gives each flat-shaded line segment
+ <inlineequation><mml:math><mml:mi mathvariant="italic">i</mml:mi></mml:math></inlineequation>
+ the
+ computed color of vertex
+ <inlineequation><mml:math>
+ <!-- eqn: i + 1:-->
+ <mml:mrow>
+ <mml:mi mathvariant="italic">i</mml:mi>
+ <mml:mo>+</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:math></inlineequation>,
+ its second vertex.
+ Counting similarly from 1,
+ the GL gives each flat-shaded polygon the computed color of the vertex listed
+ in the following table.
+ This is the last vertex to specify the polygon in all cases except single
+ polygons,
+ where the first vertex specifies the flat-shaded color.
+ </para>
+ <para>
+ </para>
+ <informaltable frame="topbot">
+ <tgroup cols="2" align="left">
+ <colspec/>
+ <colspec align="center"/>
+ <thead>
+ <row>
+ <entry rowsep="1" align="left"><emphasis role="bold">
+ Primitive Type of Polygon
+ <inlineequation><mml:math><mml:mi mathvariant="italic">i</mml:mi></mml:math></inlineequation>
+ </emphasis></entry>
+ <entry rowsep="1" align="center"><emphasis role="bold">
+ Vertex
+ </emphasis></entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry align="left">
+ Single polygon
+ (<inlineequation><mml:math>
+ <!-- eqn: i == 1:-->
+ <mml:mrow>
+ <mml:mi mathvariant="italic">i</mml:mi>
+ <mml:mo>==</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:math></inlineequation>)
+ </entry>
+ <entry align="center">
+ 1
+ </entry>
+ </row>
+ <row>
+ <entry align="left">
+ Triangle strip
+ </entry>
+ <entry align="center">
+ <inlineequation><mml:math>
+ <!-- eqn: i + 2:-->
+ <mml:mrow>
+ <mml:mi mathvariant="italic">i</mml:mi>
+ <mml:mo>+</mml:mo>
+ <mml:mn>2</mml:mn>
+ </mml:mrow>
+ </mml:math></inlineequation>
+ </entry>
+ </row>
+ <row>
+ <entry align="left">
+ Triangle fan
+ </entry>
+ <entry align="center">
+ <inlineequation><mml:math>
+ <!-- eqn: i + 2:-->
+ <mml:mrow>
+ <mml:mi mathvariant="italic">i</mml:mi>
+ <mml:mo>+</mml:mo>
+ <mml:mn>2</mml:mn>
+ </mml:mrow>
+ </mml:math></inlineequation>
+ </entry>
+ </row>
+ <row>
+ <entry align="left">
+ Independent triangle
+ </entry>
+ <entry align="center">
+ <inlineequation><mml:math>
+ <!-- eqn: 3 i:-->
+ <mml:mrow>
+ <mml:mn>3</mml:mn>
+ <mml:mo>⁢</mml:mo>
+ <mml:mi mathvariant="italic">i</mml:mi>
+ </mml:mrow>
+ </mml:math></inlineequation>
+ </entry>
+ </row>
+ <row>
+ <entry align="left">
+ Quad strip
+ </entry>
+ <entry align="center">
+ <inlineequation><mml:math>
+ <!-- eqn: 2 i + 2:-->
+ <mml:mrow>
+ <mml:mn>2</mml:mn>
+ <mml:mo>⁢</mml:mo>
+ <mml:mi mathvariant="italic">i</mml:mi>
+ <mml:mo>+</mml:mo>
+ <mml:mn>2</mml:mn>
+ </mml:mrow>
+ </mml:math></inlineequation>
+ </entry>
+ </row>
+ <row>
+ <entry align="left">
+ Independent quad
+ </entry>
+ <entry align="center">
+ <inlineequation><mml:math>
+ <!-- eqn: 4 i:-->
+ <mml:mrow>
+ <mml:mn>4</mml:mn>
+ <mml:mo>⁢</mml:mo>
+ <mml:mi mathvariant="italic">i</mml:mi>
+ </mml:mrow>
+ </mml:math></inlineequation>
+ </entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </informaltable>
+ <para>
+ Flat and smooth shading are specified by <function>glShadeModel</function> with <parameter>mode</parameter> set to
+ <constant>GL_FLAT</constant> and <constant>GL_SMOOTH</constant>, respectively.
+ </para>
+ </refsect1>
+ <refsect1 id="errors"><title>Errors</title>
+ <para>
+ <constant>GL_INVALID_ENUM</constant> is generated if <parameter>mode</parameter> is any value other than
+ <constant>GL_FLAT</constant> or <constant>GL_SMOOTH</constant>.
+ </para>
+ <para>
+ <constant>GL_INVALID_OPERATION</constant> is generated if <function>glShadeModel</function>
+ is executed between the execution of <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry>
+ and the corresponding execution of <citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>.
+ </para>
+ </refsect1>
+ <refsect1 id="associatedgets"><title>Associated Gets</title>
+ <para>
+ <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_SHADE_MODEL</constant>
+ </para>
+ </refsect1>
+ <refsect1 id="seealso"><title>See Also</title>
+ <para>
+ <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry>,
+ <citerefentry><refentrytitle>glColor</refentrytitle></citerefentry>,
+ <citerefentry><refentrytitle>glLight</refentrytitle></citerefentry>,
+ <citerefentry><refentrytitle>glLightModel</refentrytitle></citerefentry>
+ </para>
+ </refsect1>
+ <refsect1 id="Copyright"><title>Copyright</title>
+ <para>
+ Copyright <trademark class="copyright"></trademark> 1991-2006
+ Silicon Graphics, Inc. This document is licensed under the SGI
+ Free Software B License. For details, see
+ <ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>.
+ </para>
+ </refsect1>
+</refentry>
HCoop / clinton / guile-figl.git / blobdiff