The
bomb spacewarp is often good for quick explosions,
however, close inspection reveals paper thin pieces
of debris that simply fall through floors and cannot
be acted upon by other forces. If an explosion requires
debris and some control over the pieces a PArray (Particle
Array) can help. The PArray can create explosive visuals
and allow forces, such as gravity, wind, and deflectors
to act upon the pieces.
Part One - Creating A Box And
A PArray
 Create
a simple box with 3x3x3 length, width, and height segments.
This will allow the box to explode with an ample number
of particles. Refer to the Explode A Box tutorial if
you are unsure how to do this.
Next, you will create a PArray. This
can be accomplished by going to the Command Panel and
selecting the Create | Geometry | Particle Systems
| Parray option.
 Draw
the PArray as though you were creating a box. It does
not matter where the PArray is placed in the scene
as it is only a placeholder. It does not render out
and the scene does not effect anything in relation
to where it is. What matters most is the many modifications
that can be employed to create a seemingly 'chunky'
explosion based on an original source object.
Examine the option windows that are
available by making sure that the PArray is active
and then selecting the Modify tab. As with all options,
the further down the list, the more CPU intensive the
task. Not all options will be employed in this tutorial
and a lot of tweaking and experimentation can take
place after the main part of the tutorial is completed.
 Start
with the Basic Parameters. Use the Pick Object button
to select the box created earlier. Afterwards, choose
Mesh in order to view the particles created in the
viewport.
 Under
Particle Generation, lower the speed to 0 (ZERO). You
can use the default speed, but you will have more control
over the debris using Spacewarps, such as wind, gravity,
and deflectors.
 Just
as the bomb has an option to control when the explosion
should occur, the PArray also allows you to control
when it starts, ends, and how long it should live for.
Defaults are fine for now, but you may want to give
yourself some breathing room by moving the start time
to 10. Also, the particles should probably live for
as long as your animation. So if you are using the
default of 100 frames. Make the life 100.
 Under
the Particle Type rollout, make sure that Object Fragments
is chosen in order to create debris.
 Your
particles can be given a particular material by placing
it on the icon representing the PArray. However, if
you woudl like your PArray to take on the qualities
of the object it is created from, you can select to
obtain the material from the Picked Emitter.
 Finally,
under Rotation and Collision a spin can be created.
The spin must be set to 1, but by animating the Variation
you can slow down the spin over time and even stop
it. At this point you should be able to see your box
break apart, but the pieces will be spinning in their
place. In order to move the fragments in a particular
direction, their is a need to add Spacewarps to the
scene.
Part Two - Adding Spacewarps
Spacewarps can be powerful tools.
If you have already completed the Explode A Box tutorial,
you know that the bomb spacewarp is bound to a target.
In this case, several spacewarps will be bound to the
PArray in order to create movement and interaction
with its immediate surroundings.
 Select
the Create | Spacewarp | Forces | Wind
 Wind
has two main options, its strength and whether it is
directional or omni-directional. The strength starts
at 1 (or full) and can be turned to 0 (or off). The
planar vs spherical option allows you to choose a particular
direction that the wind blows or simply away from a
central point, respectivly. The placement of the wind
in relation to the object it will be bound to is important.
If you place the wind in the centre of the object it
will disperse its pieces in all directions. If the
wind is off to the left, the pieces will fly away to
the right.
 Bind
The Spacewarp to the PArray. This can be done by binding
it to the icon representing the box, or it could be
attached to any of the pieces.
 Create
a Plane underneath the box. This plane provides a visual
cue for the debris to bounce off of.
 Create
a Deflector by choosing Create | Spacewarp | Deflectors
| Deflector
 Use
the Bind To Spacewarp tool to bind the Deflector to
the PArray.
 Finally,
add some gravity to your scene and associate that with
the PArray as well. This will help bring the pieces
of debris back down after it bounces off the Deflector.
At this point you should have a PArray using a box
to emit from, Wind to blow the pieces created away,
and a Plane that has a Deflector in the same place,
but associated with the PArray in order to make it
appear to bounce off the plane. If you select the PArray
and select the Modify tab, you should see the following:
The image shows that the original
PArray is being affected by the three Spacewarps.
Part Three - Invisibility
This last section is in response to
the obvious problem of the box remaining visible, even
after the PArray's debris is thrown from the exact
location. In order to finish this illusion, the box
needs to be made invisible at the frame it is destroyed.
If the box is to be destroyed at frame 10, then the
box should disappear at the same frame.
 Open
the Track View option by selecting the Graph Editors
from the top menu options and choosing Track View |
Open Track View from the flyout.
The Track View holds information about
everything related to the current scene. It can be
quite complex, however, in this case the only thing
we are concerned with is the Visibility Track of the
box.
 Scroll
down and expand the Objects | Box01 flyouts. Notice
that there are several options in this catagory, but
nothing realted to visibility. In order to activate
this track you need to select the eyeball [ ]
on the Track View menu. Once depressed, the eyeball
becomes greyed out and a visiblity track is provided.
Add two keys to the Visibility Track by selecting the
create key button, [ ]
 The
first key should set the visiblity of the box to 1
(or full) and a second key should be set at the same
frame the PArray becomes active. The second key should
be set to 0 (or off). Keys can be edited by right clicking
on them.
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