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Obstacle Avoidance 1165
andfalloffparameters,aswellasitsweightin
the Assignments and Teams dialog, to control
its strength.
•UsetheRepel behavior (page 2–1218) to cause
crowd members to turn away from an object.
ItworksexactlylikeWallRepelexceptthatit
usesasphericalvolumeratherthanaplane.
You can set a maximum distance for the repel
effect, and describe the rate at which the repel
forceincreasesasthedelegateapproachesthe
obstacle.
Repel exerts a force on the delegate to turn it
away from the obstacle. It does not guarantee
avoidance. You must work with its Distance
and Falloff parameters, as well as its weight in
the Behav ior Assignments and Teams dialog
(page 2–1200),tocontrolitsstrength.Repel
can be used instead of the Avoid behavior as a
simple avoidance technique for non-terrestrial
creaturessuchasfishorbirds.
•UseaVector Field (page 2–1241). Thisisa
special type of space warp that crowd members
can use to move around irregular objects such
as a curved, concave surface. You can use the
Vector Field space warp in conjunction with the
Avoid behavior to make delegates slow down
when they approach a complex object, and then
go around it. This guarantees that the delegate
willnotpassthroughtheobstacle’ssurface.
You can also use the Vector Field space warp
in conjunction with the Space Warp behavior
(page 2–1221).Thissimplyexertsaforceonthe
delegate that mimics the contours of t he object.
It does not assure that the delegate will not pass
through the surface of the obstacle. You can use
a Vector Field with b oth the Space Wa rp and
Avoid behaviors to combine their effects.
Pr ocedur es
To use the Avoid behavior:
1.
Add an A void behavior to the Crowd object.
2. In the Avoid Beha vior rollout, use the None
button or the Multiple Selection button to
designate the target object or objects to avoid.
Tip: To make an entire team of delegates avoid
each other, choose all delegates in the team.
The crowd system will cause each delegate to
avoid all others except itself.
3. Tu r n on Display Ha rd Radiu s to se e t he radia l
avoidance area in viewports. Adjust the
HardRadiustotheappropriatesizeforyour
delegates.
4. Adjust the Brake Pressure to determine whether
adelegatewillslowdownwhenitencounters
an avoided object.
5. Adjust the Look Ahead parameter to determine
how many frames ahead each delegate will look
to determine the best way to avoid others.
6. Use Behavior Assignments (page 2–1200) to
assign the behavior to a delegate or team.
To use the Wall R epel behavior:
1.
On the Create panel, click Helpers, and click
Grid. Create a grid in the scene.
Tip: For best results, do not use Mir ror to
copy a grid to be used with behaviors. Use
Shi f t +Clone instead.
2. Move and rotate the grid to position it.
Tip: The Wall Repel behavior repels delegates
from the grid in the direction of grid’s local Z
axis. With the grid still selected, use the Local
coordinate system to see the direction of the
Z axis in viewports; the axis arrow points in
thedirectionofthepositiveZaxis.Checking
the Z-axis direction will speed the process of
setting up the behavior.
3. Select the crowd object, and add a Wall Repel
behav ior.
4. In the Wall Repel Behavior rollout, click None,
and pick the grid.