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1352 Chapter 16: Material Editor, Materials, and Maps
To assign a bitmap as a refraction map:
1.
In the Maps rollout, click the R efraction map
button.
2. Use the Material/Map Browser (page 2–1291)
to choose the Bitmap type.
3. Use the file dialog to choose the bitmap file.
For bitmapped refractions, y ou don’t
necessarily want to reduce the map strength.
Dis pla cement Ma pping
Material Editor > Sta ndard material > Maps rollout >
Displacement button
Using displacement mappi ng to alter a surface
A displacement map displaces the geometry of
surfaces. The effect is simi lar to using the
Displace
(page 1–608)
modifier. Unlike bump mapping
(page 2–1347)
, displacement mapping actually
changes the geometry of the surface or patch
tessellation. Displacement maps apply the g r ay
scale of the map to generate the displacement.
Lighter colors in the 2D image push outward more
strongly than darker colors, resulting in a 3D
displacement of the geometry.
Wa rn in g : A displacement map generates many
triangular faces per surface, sometimes over 1M faces
per sur face. While displacement mapping can create
good effects, there is a large cost in terms of time and
memory.
The displacement Amount is measured as a
percent a ge of the diagonal of the bounding box for
the object that contains the patch or surface. This
makes the displacement effect consistent for all
surfaces in an object, and it also means that when
you scale the object, the displacement is scaled
with it.
Yo u c a n a p p l y a d i s p l a c e m e n t m a p d i r e c t l y t o t h e
following kinds of objects:
•
Bezier patches (page 1–980)
• Editable meshes (page 1–984)
• Editable polymeshes (page 1–1012)
• NURBS surfaces (page 1–1079)
For other kinds of geometry such as primit ives,
extended primitives, compound objects, and so
on, you can’t apply displacement mapping directly.
To use displacement mapping with these kinds
of objects, apply a
Disp Approx (page 1–607)
(Displacement Approximation) modifier. This
makes the object’s surface displaceable. Disp
Approx works with any ki nd of object that you can
convert to an editable mesh.
Displacement mapping isn’t visible in view p orts
unless you apply a modifier to make it so.
•ForNURBSsurfaces,youcanmake
displacement mapping v isible in v iewports and
editable as a mesh object by using the
Displace
NURBS (page 1–501)
world space modifier.
• For editable meshes and objects with Disp
A pprox applied to them, use the
Displace Mesh
(page 1–499)
modifiertoobtainthesameeffect.
Note: If you apply a UVW Map (page 1–905)
modifier to the surface, all maps obtain their
coordinates from the modifier except for the
displacement map, which
always obtains its
coordinates from the original surface or the
Disp A ppro x modifier.
Under cert ain circumstances, such as when the
underlying mesh is fairly simple, displacement