CGTalk - thinking particles help

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neonghost

04-20-2003, 06:30 PM

Hi,

I'd appreciate any help with this problem:

I have a tube which is deformed with a bend and bulge operator. Inside the tube is an emitter which uses an xpresso expression to stay in the center of the tube as it is deformed. The emitted particles are deflected by the interior walls of the tube.

This system works fine when the deformers are not being applied, but when animated most of the particles escape the tube (even though it is relatively finely subdivided). Is there a way to increase the sampling of the TP calculations to improve collision detection, or should I further subdivide the mesh (or is it just time to rethink my approach)?

cheers,
neon

Srek

04-20-2003, 07:53 PM

Hi,
since the deformation is no smooth transition but an instant change of the position of the polygons, collision detection will only work when you use a particle offset that is high enough to provide room for the position change of the polygons.
Hope this helps
Srek

neonghost

04-21-2003, 02:59 AM

thanks, srek - however, i'm a little confused when it comes to particle offset (I presume this is in relation to the collision properties of the tube)... The deformation is not instant, and is made over the space of about 30 frames (its sort of a ping-pong loop), so I thought there was plenty of time for calculations to be made.

At the moment collision type is set to Back, with no offset - is there a more appropriate setting?

thanks,
neon

JIII

04-21-2003, 03:06 AM

try both sides collision.

here is a little trick. put your object that is being deformed into a hypernurbs object and then select the hypernurbs and click make editable. this will convert your object into all polys and convert the object into polys with the deformations still having an effect.

neonghost

04-21-2003, 03:32 AM

cheers JIII, but I don't think I've made it clear what I'm attempting to do.

The tube deflector is already a highly subdivided mesh which has a keyed bend deformer giving it a swaying motion, the emitter I have inside is emitting particles which I intend to keep within the confines of the tube as it is being deformed - by means of an Xpresso and TP expression. This works, but only to an extent - some particles rebound along the walls as it is being deformed, while the majority (I assume through bad collision detection) escape through the tube. Setting the collision method to two side results in even less collision accuracy (thus leaving me pretty confused).

JIII

04-21-2003, 03:43 AM

are you using make preveiw to check the result. cause if you are using the screbber bar it might not be accurate.

other than that. if it is accurate with our deformers, make multiples of it and then use the deformer to get it to the right location and then make its editable so its all polys. and then use one of those morph things to animate it.

never tried this so I don't know if it would work.

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