8.2.3 Scene Setup Summary
Open up the WoodBreakingFXRig_start.ma file from the companion
The scene has some basic geometry with dynamics simulated in
Blast Code (http://www.blastcode.com/)thatwasbakedontokeyframesfor
ease of use.
If you expand the origGeom group in the outliner, you will see
four subgroups. These are, as shown in Figure 8-6, in the order of
their hierarchy:
Since this example is primarily concerned with the expressions
behind the dust rig, I will keep the BlastCode talk to a minimum.
Basically, after shattering the geometry in Blast Code, I recorded it
and baked the effect into keyframes. Then I deleted the BlastCode
solver so that it could be ported to machines without the plug-in.
What was left was the layer hierarchy shown above. The
PrimaryGroup1 and SecondaryGroup1 layers contain the primary
and secondary debris, respectively. If you play back the scene, you
will see clearly that the wood breaks into a few large pieces (pri-
mary) and many small pieces (secondary).
I then duplicated those two groups with input connections so
that the animation gets transferred. The reason behind this is that in
a production pipeline, the original geometry/ animation would usu-
ally be referenced; and it is a bad idea to manipulate referenced
geometry. Your outliner should show this:
Chapter 8
Figure 8-6
I have named the duplicates emitGeoPrim and emitGeoSec. I also
assigned the objects to their respective layers for ease of use. The
ground floor is in its own group called floor, the original geometry is
in its own group called origAnim_lyr, and the duplicated geometry
that will be used as particle emitters is in its own layer called
emitGeo_lyr. Your layers should look like this:
Since you should never mess with the original referenced geometry,
we set up the particle systems on the duplicated layer. The
emitGeo_lyr layer is kept hidden because we don’t want to see two
copies of the same geometry. As we will see in the next section, the
only purpose of the duplicated geometry is to set up the particle
Now that we have everything set up in the scene, we are ready
to design the particle systems.
MEL and Expressions
Chapter 8
Figure 8-7
Figure 8-8

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