Oh, I forgot one detail though… how can you make a
certain particle be a certain instance? What I’m doing is taking a particle
from cloud 1, remove it and add one to cloud 2 with the same attributes… my
guess would have been to copy the particle ID but there’s no function to put an
ID, only to extract one. So what should I do? Add invisible particles (size=0)
to cloud 2 until I get a ID which will give me a “
instance_index
= ( particle_id * 23827 ) % nb_instances” that’s the same as the particle I’m
removing from cloud 2? That will create a bunch of useless particles for
nothing!! So if I’m to take this road, I guess I would be better off checking
in those unused particles if one exist with an ID that would match the
instance_index and use that one if it exist or add more particles if it
doesn’t? It all becomes kind of ugly don’t you think? Anyone got a better
suggestion?
Mathieu
Leclaire
R&D Programmer
Hybride Technologies
-----Original
Message-----
From: owner-xsi(at)Softimage.COM [mailto:owner-xsi(at)Softimage.COM]On Behalf Of Mathieu Leclaire
Sent: Tuesday, April 18, 2006
12:53 PM
To: XSI(at)Softimage.COM
Subject: RE: copying particle
instance from one cloud to another
Thanks
for the info… I would have never guessed that!!
-----Original
Message-----
From: owner-xsi(at)Softimage.COM [mailto:owner-xsi(at)Softimage.COM]On Behalf Of Halfdan Ingvarsson
Sent: Friday, April 14, 2006 7:40
PM
To: XSI(at)Softimage.COM
Subject: RE: copying particle
instance from one cloud to another
It's
not a particularly sophisticated algorithm either. It boils down to this:
instance_index = (
particle_id * 23827 ) % nb_instances
Random prime number
courtesy of random.org.
Assuming that the
index into the group from the SDK is the same as internally (which is usually a
pretty fair assumption) this should work for you.
- ½
From: owner-xsi(at)Softimage.COM on behalf of
Mathieu Leclaire
Sent: Fri 14-Apr-06 13:54
To: XSI(at)Softimage.COM
Subject: RE: copying particle
instance from one cloud to another
No, it picks randomly one
object for each particle.
-----Original Message-----
From: owner-xsi(at)Softimage.COM [mailto:owner-xsi(at)Softimage.COM]On
Behalf Of
Bernard Lebel
Sent: Friday, April 14, 2006 1:43 PM
To: XSI(at)Softimage.COM
Subject: Re: copying particle instance from one cloud to another
Perhaps I'm missing something, but last time I checked, all members of
the group are instantiated at each particle....
Bernard
On 4/14/06, Mathieu Leclaire <mleclair(at)hybride.com>
wrote:
> No I think you misunderstood the question... lets say my instance group
has
> a cube, a sphere and a cylinder. Each particle will instance one of the 3
> objects from the group but how can I identify which one of those 3 objects
a
> specific particle is instantiating? If one particle is instantiating a
> sphere and I want that particle to disappear and have another particle on
> the second cloud appear that will also instantiate the same sphere, not a
> cube nor a cylinder... how can I control that? How can I identify which
> object from the group that is being used by a particular particle? I'm
doing
> all this in C++ using the ParticleCloudPrimitive btw. From that, the SDK
> says I can access information like position, velocity, rotation, angular
> velocity, UVW, color, size, sprite angle, mass, age, seed, age limit,
sprite
> index and type ID... but nowhere does it talk about instances!! Anyone
ever
> had to deal with something like that?
>
> -----Original Message-----
> From: owner-xsi(at)Softimage.COM
[mailto:owner-xsi(at)Softimage.COM]On
Behalf Of
> Bernard Lebel
> Sent: Friday, April 14, 2006 12:41 PM
> To: XSI(at)Softimage.COM
> Subject: Re: copying particle instance from one cloud to another
>
> Mathieu,
>
> Is there a possibility that the instanced group has a name extremely
> close (if not the same) as the PType? This is how I could sort
> something like that, as in XSI 4.2 I could not find a way to query the
> instanced group from the PType (sorry if I missed it...)
>
> I don't "manually" set the group of particle instances. Instead,
I use
> a script that allows me to pick the object(s) I want to particle
> instantiate, then it will create the group and the PType with a near
> same name, and then perform the actual group instantiation.
>
> You could possibly write a tool that when a group is used as instance
> group in a PType, either the PType or the group is renamed to make
> sure the two conform to a traceable label.
>
> When you want to transfer information, retrieve the group by their
> name, based on the PType name, and then visit the group members.
>
> Note I have not tried to do what you're after, these are just suggestions.
>
>
> Cheers
> Bernard
>
>
> On 4/14/06, Mathieu Leclaire <mleclair(at)hybride.com>
wrote:
> >
> >
> >
> > First let me give you the context of what I'm doing: I'm creating a
> special
> > kind of collision system for particles. I'm creating a particle cloud
to
> > which I attached a scripted event evaluated on every frame that calls
a
> > custom command to verify which particles collide. If a certain
particle(s)
> > does collide, the custom command writes information to a second
clouds'
> > userDataBlob, and puts an ageLimit value to it's current age value to
make
> > that particle disappear. Then the second cloud has a custom operator
that
> > reads it's userDataBlob and if theirs information in it, it adds the
new
> > particle(s) and the clears the userDataBlob to await new information.
So
> > that's basically copying particles from one cloud to another
depending
on
> > collision calculations.
> >
> >
> >
> > But here's my problem: I can copy the ptype from one cloud to the
other
> > while creating this second cloud before I do the simulation. But I
use
> > particle instancing and in my instance group there might be more then
one
> > object so how do I know for each particle, which object it's
instantiating
> > so I can copy that information through the userDataBlob and make sure
that
> > the new particle on the second cloud instantiates the right object?
> >
> >
> >
> >
> >
> > Mathieu Leclaire
> >
> > R&D Programmer
> >
> > Hybride Technologies
>
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