Insectoids
ABSTRACT:
Insectoids is a system for
animating flying insects in Alias Power Animator 8.x. It is a random path generator; the
random paths are imported into Alias and assigned to 3D modeled insects as motion
paths.
In Insectoids, a random path connects (at least) two points: a start point and an
end point. You can explicitly specify these points or let Insectoids randomly
generate them. A start and an end point pair forms a stage. A
path can pass thorough any number of stages. To define the stages, you create a
polyline in Alias with the points you want the path to pass through as its vertices.
You save this polyline in OBJ format and import it into Insectoids. If there are n
vertices on the polyline, there will be n - 1 stages. For example, a polyline having
vertices A, B and C will have stages AB and BC. It is not compulsory to define
stages this way, Insectoids creates a stage for you when its starts up or when you reset
it.
The path parameters allow you to
make the insect fly faster or slower, cover more distance or less, and flutter a lot or
glide smoothly. You can edit these parameters on a stage by stage basis. It is
possible to assign parameter changes to all stages or let them be independent of each
other. You could therefore have an insect flying faster in one stage,
fluttering a lot in the next and covering more distance in the third. A lot of
combinations are possible, please experiment.
Though Insectoids is intended
for animating flying insects, it doesnt stop you from animating the non flying variety
like beetles and ants. These insects also move randomly but with a difference.
They move on the ground (or wall or cieling -- a 2D plane). You can generate random
paths that lie only on, say, the XY plane by having the start and the end points lie on
that plane and disabling the randomness in the Z direction.
In addition, Insectoids offers
the following convenience facilities for Alias animators:
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Paths can be exported as Polylines or
B-splines. Generally, Polylines are useful for animating insects that jitter a lot
while B-splines are useful for animating insects that glide smoothly. The vertices
of the Polyline version of the path become the Control Vertices (CVs) of the B- spline
version. Polylines represent the path accurately while B-splines dont. Use
Polylines if you want your insects to fly exactly through the stage points and at the same
time. If you want them to fly close to the points without touching them and at slightly
different times, use B-splines.
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The detail on the path can be controlled
by the size of the insect as measured in Alias. This ensures that the insect visits
all points on the path and properly negotiates its corners.
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In the 3D model of the insect, the axis
along which the head and tail is present is its orientation. When Insectoids is
given this axis, it generates a small extension (out-growth) at the start of the every
path along this axis. This acts like an handle for the insect to hold on to and
helps Alias to get the insect to follow the path correctly. It also saves the
animator from manually orienting the insect.
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Insectoids suggests the minimum number of
frames required in the animation for the insect to traverse all points on the
path. Using this value as a starting point, you can time your animation.
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Once you have the required number of 3D
insects and the random paths in Alias, the animation process is very simple. The
pseudocode below explains it all: |
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for i = 1 to n_insects
do
Pick the ith Insect
Choose Anim -> Set Motion
Pick the ith Random Path
done |
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If a macro facility were available in Alias, this process
could have been automated. On Maya, I think this is possible by writing a MEL
script. I have not worked on Maya, so if you are interested in volunteering to write
this script, please contact me |
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