<!–Converted with LaTeX2HTML 2022 (Released January 1, 2022) –> <HTML lang="en"> <HEAD> <TITLE>Contents of Mapping Functions</TITLE>
<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=utf-8"> <META NAME="viewport" CONTENT="width=device-width, initial-scale=1.0"> <META NAME="Generator" CONTENT="LaTeX2HTML v2022">
<LINK REL="STYLESHEET" HREF="texture.css">
<LINK REL="previous" HREF="node3_mn.html"> <LINK REL="up" HREF="node1_mn.html"> </HEAD>
<BODY bgcolor="#ffffff" text="#000000" link="#9944EE" vlink="#0000ff" alink="#00ff00">
<H1><A ID="SECTION00130000000000000000"> Mapping Functions</A> </H1>
<P> Mapping functions are used to apply two-dimensional textures to surfaces. Each mapping functions defines a different method of transforming a three dimensional point of intersection to a two dimensional <I>u</I> - <I>v</I> pair termed texturing coordinates. Typically, the arguments to a mapping method define a center of a projection and two non-parallel axes that define a local coordinate system.
<P> The default mapping method is termed <I>u</I> - <I>v</I> mapping or <EM>inverse mapping</EM>. Normally, there is a different inverse mapping method for each primitive type (see chapter 5). When inverse mapping is used, the point of intersection is passed to the <I>uv</I> method for the primitive that was hit.
<P>
<BR>
<IMG
STYLE="height: 2.38ex; vertical-align: 176.27ex; " SRC="img17.png"
ALT="
">
<BR>
The inverse mapping method for each primitive is described in Chapter 5.
<P>
<BR>
<IMG
STYLE="height: 2.38ex; vertical-align: 176.27ex; " SRC="img18.png"
ALT="
">
<BR>
<P>
<BR>
<IMG
STYLE="height: 2.38ex; vertical-align: 176.27ex; " SRC="img19.png"
ALT="
">
<BR>
See the description of the inverse mapping method for the
cylinder in Chapter 5. By default, the point of intersection is
projected onto a cylinder that runs through the origin along the <I>z</I>
axis, with uaxis equal to the <I>x</I> axis.
<P>
<BR>
<IMG
STYLE="height: 2.38ex; vertical-align: 176.27ex; " SRC="img20.png"
ALT="
">
<BR>
By default, a spherical mapping projects points towards the origin,
with vaxis defined to be the <I>z</I> axis and
uaxis defined to be the <I>x</I> axis.
<HR>
</BODY> </HTML>