Cre@teOnline - The Web Designer's Bible CH04 Page 20
Element Operations
Remember Attach and Detach? They work at both the 2D and 3D levels.
When 3D objects are attached to one another, their component parts
remain transformable and editable as elements. Chances are you won't use
this level of editing very often--most of the time, you'll have adjusted an
object just the way you want it before attaching it to another.
Element-level operations are virtually identical to the ones used for manip-
ulating entire objects, except that some of the face operations may be
available as well.
Displacement Mapping
Yet another tool in your arsenal of mesh manipulation weapons is dis-
placement mapping. Unlike bump mapping, which is a material-level
embellishment that affects the surface normals to make an object appear
to have projections or depressions, displacement mapping or deformation
mapping actually affects the mesh, extending it outward or inward (see
Figure 4.17). It's applied the same way as a bump map is--as a grayscale
image (refer to Chapter 6, "Texture Mapping," for more information).
Depending on the program, black pixels may have no effect, whereas white
ones cause the greatest amount of displacement, or vice-versa.
3 D G
R A P H I C S
& A
N I M A T I O N
166
F
IGURE
4.17
Displacement mapping:
(a) Grid object. (b) Radial
gradient bitmap used to
determine relative dis-
placement of vertices.
(c) Deformed grid after dis-
placement is performed.
(a)
(b)
(c)
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