<HTML>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<!-- Created on , 21 2004 by texi2html 1.64 -->
<!--
Written by: Lionel Cons <Lionel.Cons@cern.ch> (original author)
Karl Berry <karl@freefriends.org>
Olaf Bachmann <obachman@mathematik.uni-kl.de>
and many others.
Maintained by: Olaf Bachmann <obachman@mathematik.uni-kl.de>
Send bugs and suggestions to <texi2html@mathematik.uni-kl.de>
-->
<HEAD>
<TITLE>OGRE Manual: The IndexData class</TITLE>
<META NAME="description" CONTENT="OGRE Manual: The IndexData class">
<META NAME="keywords" CONTENT="OGRE Manual: The IndexData class">
<META NAME="resource-type" CONTENT="document">
<META NAME="distribution" CONTENT="global">
<META NAME="Generator" CONTENT="texi2html 1.64">
<LINK TYPE="text/css" rel="stylesheet" href="../style.css">
</HEAD>
<BODY LANG="" BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#0000FF" VLINK="#800080" ALINK="#FF0000">
<A NAME="SEC168"></A>
<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="manual_48.html#SEC167"> < </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="manual_48.html#SEC167"> Up </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="manual_50.html#SEC170"> > </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="index.html#SEC_Top">Top</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="manual_toc.html#SEC_Contents">Contents</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="manual_abt.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<HR SIZE=1>
<H3> 5.7.1 The IndexData class </H3>
<!--docid::SEC168::-->
This class summarises the information required to use a set of indexes to render geometry. It's members are as follows:
<DL COMPACT>
<DT>indexStart
<DD>The first index used by this piece of geometry; this can be useful for sharing a single index buffer among several geometry pieces.
<DT>indexCount
<DD>The number of indexes used by this particular renderable.
<DT>indexBuffer
<DD>The index buffer which is used to source the indexes.
</DL>
<P>
<A NAME="SEC169"></A>
<H3> Creating an Index Buffer </H3>
<!--docid::SEC169::-->
Index buffers are created using See section <A HREF="manual_38.html#SEC153">5.1 The Hardware Buffer Manager</A> just like vertex buffers, here's how:
<TABLE><tr><td> </td><td class=example><pre>HardwareIndexBufferSharedPtr ibuf = HardwareBufferManager::getSingleton().
createIndexBuffer(
HardwareIndexBuffer::IT_16BIT, // type of index
numIndexes, // number of indexes
HardwareBuffer::HBU_STATIC_WRITE_ONLY, // usage
false); // no shadow buffer
</pre></td></tr></table>Once again, notice that the return type is a class rather than a pointer; this is reference counted so that the buffer is automatically destroyed when no more references are made to it. The parameters to the index buffer creation are:
<DL COMPACT>
<DT>indexType
<DD>There are 2 types of index; 16-bit and 32-bit. They both perform the same way, except that the latter can address larger vertex buffers. If your buffer includes more than 65526 vertices, then you will need to use 32-bit indexes. Note that you should only use 32-bit indexes when you need to, since they incur more overhead than 16-bit vertices, and are not supported on some older hardware.
<DT>numIndexes
<DD>The number of indexes in the buffer. As with vertex buffers, you should consider whether you can use a shared index buffer which is used by multiple pieces of geometry, since there can be performance advantages to switching index buffers less often.
<DT>usage
<DD>This tells the system how you intend to use the buffer. See section <A HREF="manual_39.html#SEC154">5.2 Buffer Usage</A>
<DT>useShadowBuffer
<DD>Tells the system whether you want this buffer backed by a system-memory copy. See section <A HREF="manual_40.html#SEC155">5.3 Shadow Buffers</A>
</DL>
<P>
<A NAME="Updating Index Buffers"></A>
<HR SIZE=1>
<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="manual_48.html#SEC167"> < </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="manual_48.html#SEC167"> Up </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="manual_50.html#SEC170"> > </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="index.html#SEC_Top">Top</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="manual_toc.html#SEC_Contents">Contents</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="manual_abt.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<BR>
<FONT SIZE="-1">
This document was generated
by <I>Steve Streeting</I> on <I>, 21 2004</I>
using <A HREF="http://www.mathematik.uni-kl.de/~obachman/Texi2html
"><I>texi2html</I></A>
</BODY>
</HTML>
distrib
>
Mandriva
>
10.0
>
i586
>
media
>
contrib
>
by-pkgid
>
06719cf03808e17ae6f0852ca1052dc2
>
files
>
3642
