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Vector Field 1123
orientation of a map, relative to its geometry. To
do this, you need the third coordinate. The W
coordinate als o has a meaning for 3-dimensional
procedural materials.
Vector Field
In crowd animation (page 2–1006) ,avectorfieldis
a special t ype of space warp that crowd members
can use to move around irregular objects such
as a curved, concave surface. T he vector field
gizmo, a box-shaped lattice, is placed and sized
so that it surrounds the object to be avoided. The
vectors are generated from the lattice intersections.
These vectors are, by default, perpendicular to the
surface of the object to which the field is applied;
if necessary, you can smooth them out with a
blending function. The crowd members move
around the object by traveling perpendicular to
the vectors.
Vector Field Space War p
In crowd animation (page 2–1006) ,youcan
use the
Ve c to r Fi e l d s p a c e w a r p as a sp ace war p
behavior. A vector field allows crowd members to
move automatically around
obstacle objects of any
shape, following the object contours. It also lets
crowd members move within the confines of an
enclosed space, such as a room, w hile avoiding the
walls. You can also use Vector Field space warps to
control particle motion.
The Vector Field space warp works by generating
a number of vectors that surround an object and
are perpendicular to its sur face. Crowd animation
then uses these vectors to guide delegates around
the object by moving them per pendicular to the
vectors.
V ect ors a n d V ect or H a n d l es
Kinds of vector handles:
1. Corner
2. Smooth
3. Bezier
4. Bezier corner
Vectors are secondary control points connected to
vertices on a spline or patch object. They are also
referred to as handles or vector handles.
Vectorhandlesarevisibleassmallgreensquares
when you select a vertex. However, if the Vectors
filter is checked (for a patch object), handles can
be selected and t ransformed without selecting a
vertex first. A transform cursor appears when you
move on to a vector.
Each vertex in a shape can be one of four t ypes:
Smooth—Forces the segments into a smooth curve
tangent to the vertex.
Co rner—A llows the segments on either side of the
vertex to be at any angle.
Bezier—Provide handles, but forces the segments
into a tangent through the vertex.
B ezier Corner —Provides handles, and allows the
segments on either side of the vertex to be any
angle.