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Problem solved - Kim's mail sparked an idea in my
tired brain.
I tried plotting the particle motion this
morning, using Brads particle plotting tool, but there is no simple way to
control or fix the roll along a swimpath when dealing with xyz curves :( - so I
had almost abandoned that path.
Kims mail made me think it over and I just thought
of converting position curves to Path after plotting the particle animation, and
after removing rotation keyframes and activating tangency and upvector in the
Path Constraint all is good - only caveat is I have to do that manually, but
alas I can select them all and do it on a multiple ppg. So there is a suggestion
for an improvement on Brads CGS_Plot Particles: plot to path animation with
options for activating tangency and upvector.
Thanks guys - note for Brads Sim thread on XSIbase:
we want better (read full) oriantation control for particles!
Morten Bartholdy
3D & VFX
Artist
----- Original Message -----
Sent: Thursday, March 30, 2006 3:46
PM
Subject: RE: How to control Particle
instance orientation?
I had to deal with this a year or so ago. You're right,
the particle orientatin will flip. You're also right about orientation being a
problem with deformed particles.
My solution was to build a scripted op onto the particles
that did the orientation properly, using an up vector. It wasn't that hard,
but then it's only not hard if you have the relevant
skills.
K.
From: owner-xsi(at)Softimage.COM
[mailto:owner-xsi(at)Softimage.COM] On Behalf Of Morten
Bartholdy
Sent: 30-March-2006 14:38
To:
XSI(at)Softimage.COM
Subject: Re: How to control Particle instance
orientation?
Hi Eric,
I suppose you mean deforming the cloud to get a
swimming school of fish rather than use goals!? I guess it is worth a try, I
just see a problem with particle orientation when the particlecloud is
deformed. I don't recall if there is a script somewhere to fix
that.
Morten
----- Original Message -----
Sent: Thursday, March 30, 2006 3:00
PM
Subject: Re: How to control Particle
instance orientation?
Morton,
Have you tried deforming your cloud with a cage deformer or a lattice
instead of directly on a curve?
I usually use a lattice deformed on a curve, it appears less
rigid. Also you can get a lot of nice secondary anmation by
attaching a slow shape jitter or a wave or even animated cluster
centers on point along the curve. I am not sure what this will do to
the up vectors, but I suspect it might handle it differently. Worth
a try.
Eric
Freelance 3-D Animator, F/X Artist
----- Original Message ---- From: Morten Bartholdy
<xsi(at)colorshopvfx.dk> To: XSI(at)Softimage.COM Sent: Thursday,
March 30, 2006 3:17:19 AM Subject: Re: How to control Particle instance
orientation?
Hi Mathieu,
Yes the roll provides active control -
actually if I for instance leave the roll at 90, which should
make the fish swim on their side, they flip for every turn in the goals
path, which makes me think there is some upvector control in play under
the hood.
In my test scene I have the goal following a
path which is roughly shaped like an S. For every turn the particles bank
or roll and I have yet to find a way to avoid or control that precisely.
Actually it seems the amount of roll is not the same for every turn. The
trouble is that if I try controlling it by keyframing the Rotation
Velocity Roll, the fish in the front rolls before the one in the back of
the school, which is why I'd rather find a sort of upvector
contraint.
You can see the problem in this
movie:
Notice how the particles are actually being
orientated with something like an upvector constraint as the goal takes
effect shortly after emission, and at the right turn they roll almost on
their side. This is directly influenced by the sharpness of the turn on
the path, a bit like the orientation problems when extruding a
curveprofile on a curve.
Any hellp is much appreciated.
Morten Bartholdy
3D & VFX
Artist
----- Original Message -----
Sent: Wednesday, March 29, 2006
5:30 PM
Subject: RE: How to control
Particle instance orientation?
Doesnt
the roll parameter from the Rotation Velocity control that? Maybe Im
misinterpreting your question but seem to me thats the control to play
with. The other way would be to create a scripted particle event and
control the orientation from a script. Im not sure if Im being very
helpful here so feel free to elaborate a bit more on the problem if you
want more help.
Mathieu
Leclaire
R&D
Programmer
Hybride
Technologies
-----Original
Message-----
From:
owner-xsi(at)Softimage.COM [mailto:owner-xsi(at)Softimage.COM]On Behalf Of Morten
Bartholdy
Sent:
Wednesday, March 29, 2006 2:35 AM
To: XSI(at)Softimage.COM
Subject: How to control Particle
instance orientation?
Hi
all,
I am creating
a school of fish using of instances on particles following a goal,
and it is sort of working alright. Problem is to control the upvector of
the instances - the fish roll on their path when the goal changes
direction. I have Align on velocity on and this is working fine, the
instances direction use rotation, and face direction use rotation which
I am not quite sure has an effect on the instances, but apart from
plotting and controlling the upvector directly, is there something for
controlling the roll I have missed?
Morten
Bartholdy
3D & VFX Artist
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