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+<?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="gluNurbsProperty">
+ <refmeta>
+ <refmetainfo>
+ <copyright>
+ <year>1991-2006</year>
+ <holder>Silicon Graphics, Inc.</holder>
+ </copyright>
+ </refmetainfo>
+ <refentrytitle>gluNurbsProperty</refentrytitle>
+ <manvolnum>3G</manvolnum>
+ </refmeta>
+ <refnamediv>
+ <refname>gluNurbsProperty</refname>
+ <refpurpose>set a NURBS property</refpurpose>
+ </refnamediv>
+ <refsynopsisdiv><title>C Specification</title>
+ <funcsynopsis>
+ <funcprototype>
+ <funcdef>void <function>gluNurbsProperty</function></funcdef>
+ <paramdef>GLUnurbs* <parameter>nurb</parameter></paramdef>
+ <paramdef>GLenum <parameter>property</parameter></paramdef>
+ <paramdef>GLfloat <parameter>value</parameter></paramdef>
+ </funcprototype>
+ </funcsynopsis>
+ </refsynopsisdiv>
+ <!-- eqn: ignoring delim $$ -->
+ <refsect1 id="parameters"><title>Parameters</title>
+ <variablelist>
+ <varlistentry>
+ <term><parameter>nurb</parameter></term>
+ <listitem>
+ <para>
+ Specifies the NURBS object (created with <citerefentry><refentrytitle>gluNewNurbsRenderer</refentrytitle></citerefentry>).
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>property</parameter></term>
+ <listitem>
+ <para>
+ Specifies the property to be set. Valid values are
+ <constant>GLU_SAMPLING_TOLERANCE</constant>,
+ <constant>GLU_DISPLAY_MODE</constant>,
+ <constant>GLU_CULLING</constant>,
+ <constant>GLU_AUTO_LOAD_MATRIX</constant>,
+ <constant>GLU_PARAMETRIC_TOLERANCE</constant>,
+ <constant>GLU_SAMPLING_METHOD</constant>,
+ <constant>GLU_U_STEP</constant>,
+ <constant>GLU_V_STEP</constant>, or
+ <constant>GLU_NURBS_MODE</constant>.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>value</parameter></term>
+ <listitem>
+ <para>
+ Specifies the value of the indicated property.
+ It may be a numeric value or one of
+ <constant>GLU_OUTLINE_POLYGON</constant>,
+ <constant>GLU_FILL</constant>,
+ <constant>GLU_OUTLINE_PATCH</constant>,
+ <constant>GLU_TRUE</constant>,
+ <constant>GLU_FALSE</constant>,
+ <constant>GLU_PATH_LENGTH</constant>,
+ <constant>GLU_PARAMETRIC_ERROR</constant>,
+ <constant>GLU_DOMAIN_DISTANCE</constant>,
+ <constant>GLU_NURBS_RENDERER</constant>, or
+ <constant>GLU_NURBS_TESSELLATOR</constant>.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+ <refsect1 id="description"><title>Description</title>
+ <para>
+ <function>gluNurbsProperty</function> is used to control properties stored in a NURBS object. These
+ properties affect the way that a NURBS curve is rendered. The accepted
+ values for <parameter>property</parameter> are as follows:
+ </para>
+ <variablelist>
+ <varlistentry>
+ <term><constant>GLU_NURBS_MODE</constant></term>
+ <listitem>
+ <para>
+ <parameter>value</parameter> should be set to be either <constant>GLU_NURBS_RENDERER</constant> or
+ <constant>GLU_NURBS_TESSELLATOR</constant>. When set to <constant>GLU_NURBS_RENDERER</constant>, NURBS objects
+ are tessellated into OpenGL primitives and sent to the pipeline for
+ rendering. When set to <constant>GLU_NURBS_TESSELLATOR</constant>, NURBS objects are
+ tessellated into OpenGL primitives but the vertices, normals, colors, and/or textures are
+ retrieved back through a callback interface (see <citerefentry><refentrytitle>gluNurbsCallback</refentrytitle></citerefentry>). This allows the user to cache the
+ tessellated results for further processing.
+ The initial value is <constant>GLU_NURBS_RENDERER</constant>.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><constant>GLU_SAMPLING_METHOD</constant> </term>
+ <listitem>
+ <para>
+ Specifies how a NURBS surface should be
+ tessellated.
+ <parameter>value</parameter> may be one of <constant>GLU_PATH_LENGTH</constant>,
+ <constant>GLU_PARAMETRIC_ERROR</constant>, <constant>GLU_DOMAIN_DISTANCE</constant>,
+ <constant>GLU_OBJECT_PATH_LENGTH</constant>, or
+ <constant>GLU_OBJECT_PARAMETRIC_ERROR</constant>.
+ When set to <constant>GLU_PATH_LENGTH</constant>, the surface is rendered so that
+ the maximum length, in
+ pixels, of the edges of the tessellation polygons is no greater than
+ what is specified by <constant>GLU_SAMPLING_TOLERANCE</constant>.
+ </para>
+ <para>
+ <constant>GLU_PARAMETRIC_ERROR</constant> specifies that the surface is rendered in such a
+ way that the value specified by <constant>GLU_PARAMETRIC_TOLERANCE</constant> describes the
+ maximum distance, in pixels, between the tessellation polygons and the
+ surfaces they approximate.
+ </para>
+ <para>
+ <constant>GLU_DOMAIN_DISTANCE</constant> allows users to specify, in parametric coordinates,
+ how many sample points per unit length are taken in <emphasis>u</emphasis>, <emphasis>v</emphasis>
+ direction.
+ </para>
+ <para>
+ <constant>GLU_OBJECT_PATH_LENGTH</constant> is similar to <constant>GLU_PATH_LENGTH</constant>
+ except that it is view independent; that is, the surface is rendered so that the maximum length, in object space, of edges of the tessellation polygons is no greater than what is specified by <constant>GLU_SAMPLING_TOLERANCE</constant>.
+ </para>
+ <para>
+ <constant>GLU_OBJECT_PARAMETRIC_ERROR</constant> is similar to <constant>GLU_PARAMETRIC_ERROR</constant> except that it is view independent; that is, the surface is rendered in such a way that the value specified by <constant>GLU_PARAMETRIC_TOLERANCE</constant> describes the maximum distance, in object space, between the tessellation polygons and the surfaces they approximate.
+ </para>
+ <para>
+ The initial value of <constant>GLU_SAMPLING_METHOD</constant> is <constant>GLU_PATH_LENGTH</constant>.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><constant>GLU_SAMPLING_TOLERANCE</constant></term>
+ <listitem>
+ <para>
+ Specifies the maximum length, in pixels or in object space length unit,
+ to use when the sampling method is set to <constant>GLU_PATH_LENGTH</constant> or
+ <constant>GLU_OBJECT_PATH_LENGTH</constant>.
+ The NURBS code is conservative when rendering a curve
+ or surface, so the actual length can be somewhat shorter. The initial
+ value is 50.0 pixels.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><constant>GLU_PARAMETRIC_TOLERANCE</constant></term>
+ <listitem>
+ <para>
+ Specifies the maximum distance, in pixels or in object space length unit,
+ to use when the sampling method is <constant>GLU_PARAMETRIC_ERROR</constant> or
+ <constant>GLU_OBJECT_PARAMETRIC_ERROR</constant>.
+ The initial value is 0.5.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><constant>GLU_U_STEP</constant></term>
+ <listitem>
+ <para>
+ Specifies the number of sample points per unit length taken
+ along the <emphasis>u</emphasis> axis in parametric coordinates. It is needed when
+ <constant>GLU_SAMPLING_METHOD</constant> is set to <constant>GLU_DOMAIN_DISTANCE</constant>.
+ The initial value is 100.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><constant>GLU_V_STEP</constant></term>
+ <listitem>
+ <para>
+ Specifies the number of sample points per unit length taken
+ along the <emphasis>v</emphasis> axis in parametric coordinate. It is needed when
+ <constant>GLU_SAMPLING_METHOD</constant> is set to <constant>GLU_DOMAIN_DISTANCE</constant>. The initial
+ value is 100.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><constant>GLU_DISPLAY_MODE</constant></term>
+ <listitem>
+ <para>
+ <parameter>value</parameter> can be set to
+ <constant>GLU_OUTLINE_POLYGON</constant>, <constant>GLU_FILL</constant>, or
+ <constant>GLU_OUTLINE_PATCH</constant>.
+ When <constant>GLU_NURBS_MODE</constant> is set to be <constant>GLU_NURBS_RENDERER</constant>,
+ <parameter>value</parameter> defines how a NURBS surface should be rendered.
+ When <parameter>value</parameter> is set to <constant>GLU_FILL</constant>, the surface is rendered as a
+ set of polygons. When <parameter>value</parameter> is set to
+ <constant>GLU_OUTLINE_POLYGON</constant>, the NURBS library draws only the outlines
+ of the polygons created by tessellation. When <parameter>value</parameter> is set to
+ <constant>GLU_OUTLINE_PATCH</constant> just the outlines of patches and trim
+ curves defined by the user are drawn.
+ </para>
+ <para>
+ When <constant>GLU_NURBS_MODE</constant> is set to be <constant>GLU_NURBS_TESSELLATOR</constant>,
+ <parameter>value</parameter> defines how a NURBS surface should be tessellated.
+ When <constant>GLU_DISPLAY_MODE</constant> is set to <constant>GLU_FILL</constant> or
+ <constant>GLU_OUTLINE_POLYGON</constant>,
+ the NURBS surface is tessellated into OpenGL triangle primitives that can be
+ retrieved back through callback functions. If <constant>GLU_DISPLAY_MODE</constant> is set to
+ <constant>GLU_OUTLINE_PATCH</constant>, only the outlines of the patches and trim curves are generated as a sequence of line strips that can be retrieved back through callback functions.
+ </para>
+ <para>
+ The initial value is <constant>GLU_FILL</constant>.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><constant>GLU_CULLING</constant></term>
+ <listitem>
+ <para>
+ <parameter>value</parameter> is a boolean value that, when set to <constant>GLU_TRUE</constant>, indicates that
+ a NURBS curve should be discarded prior to tessellation if its control points
+ lie outside the current viewport. The initial value is <constant>GLU_FALSE</constant>.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><constant>GLU_AUTO_LOAD_MATRIX</constant></term>
+ <listitem>
+ <para>
+ <parameter>value</parameter> is a boolean value. When set to <constant>GLU_TRUE</constant>, the NURBS code
+ downloads the projection matrix, the modelview matrix, and the
+ viewport from the GL server to compute sampling and
+ culling
+ matrices for each NURBS curve that is rendered. Sampling and culling matrices
+ are required to determine the tessellation of a NURBS surface into line segments
+ or polygons and to cull a NURBS surface if it lies outside the viewport.
+ </para>
+ <para>
+ If this mode is set to <constant>GLU_FALSE</constant>, then the program needs
+ to provide a projection matrix, a modelview matrix, and a viewport
+ for the NURBS renderer to use to construct sampling and culling matrices.
+ This can be done with the <citerefentry><refentrytitle>gluLoadSamplingMatrices</refentrytitle></citerefentry> function.
+ This mode is initially set to <constant>GLU_TRUE</constant>.
+ Changing it from <constant>GLU_TRUE</constant> to <constant>GLU_FALSE</constant> does not affect
+ the sampling and culling matrices until
+ <citerefentry><refentrytitle>gluLoadSamplingMatrices</refentrytitle></citerefentry>
+ is called.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+ <refsect1 id="notes"><title>Notes</title>
+ <para>
+ If <constant>GLU_AUTO_LOAD_MATRIX</constant> is true, sampling and culling may be
+ executed incorrectly if NURBS routines are compiled into a display list.
+ </para>
+ <para>
+ A <parameter>property</parameter> of
+ <constant>GLU_PARAMETRIC_TOLERANCE</constant>,
+ <constant>GLU_SAMPLING_METHOD</constant>,
+ <constant>GLU_U_STEP</constant>, or
+ <constant>GLU_V_STEP</constant>,
+ or a <parameter>value</parameter> of
+ <constant>GLU_PATH_LENGTH</constant>,
+ <constant>GLU_PARAMETRIC_ERROR</constant>,
+ <constant>GLU_DOMAIN_DISTANCE</constant>
+ are only available if the GLU version is 1.1 or greater. They are not
+ valid parameters in GLU 1.0.
+ </para>
+ <para>
+ <citerefentry><refentrytitle>gluGetString</refentrytitle></citerefentry> can
+ be used to determine the GLU version.
+ </para>
+ <para>
+ <constant>GLU_NURBS_MODE</constant> is only available if the GLU version is 1.3 or
+ greater.
+ </para>
+ <para>
+ The <constant>GLU_OBJECT_PATH_LENGTH</constant> and <constant>GLU_OBJECT_PARAMETRIC_ERROR</constant>
+ values for the <constant>GLU_SAMPLING_METHOD</constant> property are only available if
+ the GLU version is 1.3 or greater.
+ </para>
+ </refsect1>
+ <refsect1 id="seealso"><title>See Also</title>
+ <para>
+ <citerefentry><refentrytitle>gluGetNurbsProperty</refentrytitle></citerefentry>,
+ <citerefentry><refentrytitle>gluGetString</refentrytitle></citerefentry>,
+ <citerefentry><refentrytitle>gluLoadSamplingMatrices</refentrytitle></citerefentry>,
+ <citerefentry><refentrytitle>gluNewNurbsRenderer</refentrytitle></citerefentry>,
+ <citerefentry><refentrytitle>gluNurbsCallback</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