mirror of
https://github.com/Ryujinx/Opentk.git
synced 2024-12-26 18:15:39 +00:00
157 lines
8 KiB
XML
157 lines
8 KiB
XML
<?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="gluTessProperty">
|
|
<refmeta>
|
|
<refmetainfo>
|
|
<copyright>
|
|
<year>1991-2006</year>
|
|
<holder>Silicon Graphics, Inc.</holder>
|
|
</copyright>
|
|
</refmetainfo>
|
|
<refentrytitle>gluTessProperty</refentrytitle>
|
|
<manvolnum>3G</manvolnum>
|
|
</refmeta>
|
|
<refnamediv>
|
|
<refname>gluTessProperty</refname>
|
|
<refpurpose>set a tessellation object property</refpurpose>
|
|
</refnamediv>
|
|
<refsynopsisdiv><title>C Specification</title>
|
|
<funcsynopsis>
|
|
<funcprototype>
|
|
<funcdef>void <function>gluTessProperty</function></funcdef>
|
|
<paramdef>GLUtesselator* <parameter>tess</parameter></paramdef>
|
|
<paramdef>GLenum <parameter>which</parameter></paramdef>
|
|
<paramdef>GLdouble <parameter>data</parameter></paramdef>
|
|
</funcprototype>
|
|
</funcsynopsis>
|
|
</refsynopsisdiv>
|
|
<!-- eqn: ignoring delim $$ -->
|
|
<refsect1 id="parameters"><title>Parameters</title>
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><parameter>tess</parameter></term>
|
|
<listitem>
|
|
<para>
|
|
Specifies the tessellation object (created with <citerefentry><refentrytitle>gluNewTess</refentrytitle></citerefentry>).
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><parameter>which</parameter></term>
|
|
<listitem>
|
|
<para>
|
|
Specifies the property to be set. Valid values are
|
|
<constant>GLU_TESS_WINDING_RULE</constant>,
|
|
<constant>GLU_TESS_BOUNDARY_ONLY</constant>, and
|
|
<constant>GLU_TESS_TOLERANCE</constant>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><parameter>data</parameter></term>
|
|
<listitem>
|
|
<para>
|
|
Specifies the value of the indicated property.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</refsect1>
|
|
<refsect1 id="description"><title>Description</title>
|
|
<para>
|
|
<function>gluTessProperty</function> is used to control properties stored in a tessellation object. These
|
|
properties affect the way that the polygons are interpreted and rendered.
|
|
The legal values for <parameter>which</parameter> are as follows:
|
|
</para>
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><constant>GLU_TESS_WINDING_RULE</constant> </term>
|
|
<listitem>
|
|
<para>
|
|
Determines which parts of the polygon are on the ``interior''.
|
|
<parameter>data</parameter> may be set to one of <constant>GLU_TESS_WINDING_ODD</constant>,
|
|
<constant>GLU_TESS_WINDING_NONZERO</constant>, <constant>GLU_TESS_WINDING_POSITIVE</constant>,
|
|
<constant>GLU_TESS_WINDING_NEGATIVE</constant>, or <constant>GLU_TESS_WINDING_ABS_GEQ_TWO</constant>.
|
|
</para>
|
|
<para>
|
|
To understand how the winding rule works, consider that the input
|
|
contours partition the plane into regions. The winding rule determines which
|
|
of these regions are inside the polygon.
|
|
</para>
|
|
<para>
|
|
For a single contour C, the winding number of a point x is simply the signed
|
|
number of revolutions we make around x as we travel once around C
|
|
(where CCW is positive). When there are several contours, the individual
|
|
winding numbers are summed. This procedure associates a signed integer
|
|
value with each point x in the plane. Note that the winding number is the
|
|
same for all points in a single region.
|
|
</para>
|
|
<para>
|
|
The winding rule classifies a region as ``inside'' if its winding number
|
|
belongs to the chosen category (odd, nonzero, positive, negative, or
|
|
absolute value of at least two). The previous GLU tessellator (prior to
|
|
GLU 1.2) used the ``odd'' rule. The ``nonzero'' rule is another common way to
|
|
define the interior. The other three rules are useful for polygon CSG
|
|
operations.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><constant>GLU_TESS_BOUNDARY_ONLY</constant> </term>
|
|
<listitem>
|
|
<para>
|
|
Is a boolean value (``value'' should be set
|
|
to GL_TRUE or GL_FALSE). When set to GL_TRUE, a set of closed contours
|
|
separating the polygon interior and exterior are returned instead of a
|
|
tessellation. Exterior contours are oriented CCW with respect to the
|
|
normal; interior contours are oriented CW. The <constant>GLU_TESS_BEGIN</constant>
|
|
and <constant>GLU_TESS_BEGIN_DATA</constant> callbacks use the type GL_LINE_LOOP for
|
|
each contour.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><constant>GLU_TESS_TOLERANCE</constant></term>
|
|
<listitem>
|
|
<para>
|
|
Specifies a tolerance for merging features to reduce the size of the output.
|
|
For example, two vertices that are very close to each other might be
|
|
replaced by a single vertex. The tolerance is multiplied by the largest
|
|
coordinate magnitude of any input vertex; this specifies the maximum
|
|
distance that any feature can move as the result of a single merge
|
|
operation. If a single feature takes part in several merge operations, the
|
|
total distance moved could be larger.
|
|
</para>
|
|
<para>
|
|
Feature merging is completely optional; the tolerance is only a hint.
|
|
The implementation is free to merge in some cases and not in others, or to
|
|
never merge features at all. The initial tolerance is 0.
|
|
</para>
|
|
<para>
|
|
The current implementation merges vertices only if they are exactly
|
|
coincident, regardless of the current tolerance. A vertex is spliced into
|
|
an edge only if the implementation is unable to distinguish which side of
|
|
the edge the vertex lies on. Two edges are merged only when both endpoints
|
|
are identical.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</refsect1>
|
|
<refsect1 id="seealso"><title>See Also</title>
|
|
<para>
|
|
<citerefentry><refentrytitle>gluGetTessProperty</refentrytitle></citerefentry>,
|
|
<citerefentry><refentrytitle>gluNewTess</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>
|