Simulation - Animating with Blender: How to Create Short Animations from Start to Finish - page 258

Cloth simulation generates cache fi les, much like the fl uid simulator, that must “follow” the fi le if it is moved
to a different computer or directory for rendering. Once again, we'll look at that in Chapter 15: Rendering
and Compositing.

Rigid Bodies

Certain situations arise in an animation that are just too diffi cult to animate realistically by hand. Imagine a
closet full of sports equipment emptying itself into a room, or two hundred bricks falling onto a character's
head. Even simpler, think of a rubber ball thrown into a kitchen, bouncing and spinning until it fi nally comes
to rest. Any of these things could be animated by hand, but the physical movements are so exact that to mimic
their behavior realistically with keyframing would take ages.

In these cases, a Rigid Body simulation is called for.
Setting up such a simulation is a little more diffi cult
than using the Fluid or Cloth simulators, but the
results are usually more predictable and easier to inte-
grate into your fi nished animation.

Figure 14.31 shows a series of canisters sitting near
the edge of the kitchen counter from the Beast's
kitchen set. If we wanted the Beast or the dog to run
by and knock the canisters off so that they fell, col-
lided, and clattered on the ground realistically, a rigid
body simulation would be the perfect way to do so.

Figure 14.31 Canisters on the edge of disaster

Unless you have worked with games or Rigid Bodies
before, you have probably not ventured into the Logic
context of the buttons window. First, you need to con-
struct a low resolution proxy scene that contains simple
objects representing everything that will interact within
the simulation. The physics system works much bet-
ter with lower polygon objects than with the more
detailed levels of geometry than you are probably using
for your production. In this case, the canisters will be
represented by cylinders, the counter by a scaled cube,
and the ground by a plane. We'll just use an icosphere
to initiate the collisions. This original setup is shown in
Figure 14.32.

Each item in the simulation must be initialized for
the physics engine by enabling its Actor button in
the Logic buttons, shown in Figure 14.33. Below the

Figure 14.32 The low resolution set for the rigid body
simulation