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Vector Field 1029
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 2–1154),avectorfieldis
a special t ype of space warp that crowd members
can use to move around irreg ular objects such
as a curved, concave surface. The 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, per p endicular 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 2–1154),youcanuse
the Vector Field space warp (page 2–1241) as a
space warp behavior. A vector field allows crowd
members to move automatically around obstacle
objects of any shape, following the object contours.
It also lets crowd membe rs move w ithin the
confines of an enclosed space, such as a room,
whileavoidingthewalls.YoucanalsouseVector
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 surface. Crowd animation
then uses these vectors to guide delegates around
the object by moving them perpendicular to the
vectors.
V ect ors an d Vect o r 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 transformed without selecting a
vertex first. A transform cursor appears when you
move onto a vector .
Each vertex in a shape can be one of four types:
Smooth—Forces the segments into a smooth curve
tangent to the vertex.
Co rner—Allows 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.