134 lines
6.5 KiB
XML
134 lines
6.5 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="glClipPlane">
|
|
<refmeta>
|
|
<refmetainfo>
|
|
<copyright>
|
|
<year>1991-2006</year>
|
|
<holder>Silicon Graphics, Inc.</holder>
|
|
</copyright>
|
|
</refmetainfo>
|
|
<refentrytitle>glClipPlane</refentrytitle>
|
|
<manvolnum>3G</manvolnum>
|
|
</refmeta>
|
|
<refnamediv>
|
|
<refname>glClipPlane</refname>
|
|
<refpurpose>specify a plane against which all geometry is clipped</refpurpose>
|
|
</refnamediv>
|
|
<refsynopsisdiv><title>C Specification</title>
|
|
<funcsynopsis>
|
|
<funcprototype>
|
|
<funcdef>void <function>glClipPlane</function></funcdef>
|
|
<paramdef>GLenum <parameter>plane</parameter></paramdef>
|
|
<paramdef>const GLdouble * <parameter>equation</parameter></paramdef>
|
|
</funcprototype>
|
|
</funcsynopsis>
|
|
</refsynopsisdiv>
|
|
<!-- eqn: ignoring delim $$ -->
|
|
<refsect1 id="parameters"><title>Parameters</title>
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><parameter>plane</parameter></term>
|
|
<listitem>
|
|
<para>
|
|
Specifies which clipping plane is being positioned.
|
|
Symbolic names of the form <constant>GL_CLIP_PLANE</constant><emphasis>i</emphasis>,
|
|
where <emphasis>i</emphasis> is an integer between 0 and <constant>GL_MAX_CLIP_PLANES</constant>
|
|
<inlineequation><mml:math>
|
|
<!-- eqn: - 1:-->
|
|
<mml:mn>-1</mml:mn>
|
|
</mml:math></inlineequation>,
|
|
are accepted.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><parameter>equation</parameter></term>
|
|
<listitem>
|
|
<para>
|
|
Specifies the address of an array of four double-precision floating-point values.
|
|
These values are interpreted as a plane equation.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</refsect1>
|
|
<refsect1 id="description"><title>Description</title>
|
|
<para>
|
|
Geometry is always clipped against the boundaries of a six-plane frustum
|
|
in <emphasis>x</emphasis>, <emphasis>y</emphasis>, and <emphasis>z</emphasis>.
|
|
<function>glClipPlane</function> allows the specification of additional planes,
|
|
not necessarily perpendicular to the <emphasis>x</emphasis>, <emphasis>y</emphasis>, or <emphasis>z</emphasis> axis,
|
|
against which all geometry is clipped.
|
|
To determine the maximum number of additional clipping planes, call
|
|
<citerefentry><refentrytitle>glGetIntegerv</refentrytitle></citerefentry> with argument <constant>GL_MAX_CLIP_PLANES</constant>. All
|
|
implementations support at least six such clipping planes.
|
|
Because the resulting clipping region is the intersection
|
|
of the defined half-spaces,
|
|
it is always convex.
|
|
</para>
|
|
<para>
|
|
<function>glClipPlane</function> specifies a half-space using a four-component plane equation.
|
|
When <function>glClipPlane</function> is called,
|
|
<parameter>equation</parameter> is transformed by the inverse of the modelview matrix
|
|
and stored in the resulting eye coordinates.
|
|
Subsequent changes to the modelview matrix have no effect on the
|
|
stored plane-equation components.
|
|
If the dot product of the eye coordinates of a vertex with the
|
|
stored plane equation components is positive or zero,
|
|
the vertex is <emphasis>in</emphasis> with respect to that clipping plane.
|
|
Otherwise, it is <emphasis>out</emphasis>.
|
|
</para>
|
|
<para>
|
|
To enable and disable clipping planes, call
|
|
<citerefentry><refentrytitle>glEnable</refentrytitle></citerefentry> and <citerefentry><refentrytitle>glDisable</refentrytitle></citerefentry> with the argument
|
|
<constant>GL_CLIP_PLANE</constant><emphasis>i</emphasis>,
|
|
where <emphasis>i</emphasis> is the plane number.
|
|
</para>
|
|
<para>
|
|
All clipping planes are initially defined as (0, 0, 0, 0) in eye coordinates
|
|
and are
|
|
disabled.
|
|
</para>
|
|
</refsect1>
|
|
<refsect1 id="notes"><title>Notes</title>
|
|
<para>
|
|
It is always the case that <constant>GL_CLIP_PLANE</constant>
|
|
<inlineequation><mml:math><mml:mi mathvariant="italic">i</mml:mi></mml:math></inlineequation>
|
|
= <constant>GL_CLIP_PLANE0</constant> +
|
|
<inlineequation><mml:math><mml:mi mathvariant="italic">i</mml:mi></mml:math></inlineequation>.
|
|
</para>
|
|
</refsect1>
|
|
<refsect1 id="errors"><title>Errors</title>
|
|
<para>
|
|
<constant>GL_INVALID_ENUM</constant> is generated if <parameter>plane</parameter> is not an accepted value.
|
|
</para>
|
|
<para>
|
|
<constant>GL_INVALID_OPERATION</constant> is generated if <function>glClipPlane</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>glGetClipPlane</refentrytitle></citerefentry>
|
|
</para>
|
|
<para>
|
|
<citerefentry><refentrytitle>glIsEnabled</refentrytitle></citerefentry> with argument <constant>GL_CLIP_PLANE</constant><emphasis>i</emphasis>
|
|
</para>
|
|
</refsect1>
|
|
<refsect1 id="seealso"><title>See Also</title>
|
|
<para>
|
|
<citerefentry><refentrytitle>glEnable</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>
|