8
1428 Chapter 16: Material Editor, Materials, and Maps
mentalraymapsinthebrowser’slistareshownwithyellow
icons.
Tip: When the default scanline renderer is active,
you
can
view mental ray shaders in the Browser
list, a nd assign them, by tur ning on Incompatible
in the Show group. Incompatible shaders in the
list are displayed in gray.
Maps and Mapping Coordinates
Maps have a spatial orientation. When you
apply a material w ith maps in it to an object, the
object must have mapping coordinates. These are
specified in terms of UVW axes local to the object.
Most objects have a Generate Mapping
Coordinates toggle. You can turn this on to
provide default mapping coordinates. If the object
hasthistoggle,itisalsoturnedonautomatically
when you render the scene, or use
Show Map In
View por t (page 2–1289)
.
Some objects, such as editable meshes, don’t have
automatic mapping coordinates. For these types of
objects, you can assign coordinates by applying a
UVW Map modifier (page 1–905)
. If you assign a
map that uses a mapping channel, but don’t apply
a UVW Map modifier to the object, the renderer
displays a warning that lists objects that require
mapping coordinates. You can also u se UVW Map
to change an object’s default mapping.
See
Mapping Coordinates (page 2–1249)
.
UVW Mapping Coordinate Channels
Each object can have from 1 to 99 UVWmapping
coordinate channels. The default mapping (from
the Generate Mapping Coordinates toggle) is
alwaysUVW1.TheUVWMapmodifiercansend
coordinates to any of these channels.
Each map in a material can use any UVW channel
(if present), or other typ e of mapping that depends
on whether the map is 2D or 3D.
You can set the mapping channel used by
NURBS
surface (page 1–1102)
sub-objects in their creation
or modification parameters.
Mapping for 2D Maps
You can position a 2D map on the surface of an
object by us ing a map channel, any assigned vertex
color,orthelocalorworldcoordinatesystems.You
can also choose different environment mappings.
See
Coordinates Rollout (2D) (page 2–1434)
.
Mapping for 3D Maps
You can position a 3D map w ithin the volume of an
object by us ing a map channel, any assigned vertex
color, or the local or world coordinate systems. See
Coordinates Rollout (3D) (page 2–1472)
.
Noise for Maps
Random noise values increase the complexity of
maps and can give them a more natural look. For
2D maps, see
Noise Rollout (2D) (page 2–1439)
.
For 3D maps, you can assig n a separate Noise map.
See
Noise Map (page 2–1484)
.