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cavetroll
06-15-2003, 02:19 PM
heya everybody.
I am using spline IKs for secondary animation bits of my character, simulating the jiggle of a piece of hair, for example. turned the splines into soft bodies, adjusted the goalWeightPP for each particle, to have them lowered when reaching the end of the spline. connected a gravity field to the softBody and now I got a nice swinging piece of hair.
so far everything is fine. now the problem. when further adjusting the goalPP for my particles via componentEditor they snap back to their values I gave them right after creating the softBody. in fact, for the first playback after changing the values everything works fine just until to the moment my time snaps back to frame 1, the values snap back to the old ones. I can see that visually and in the component editor.
same thing happens to the collision object I created for the head (I do not want my SB-curve to penetrate the head). if i connect the particles to the spline the first time (on frame one for example), hit play, everything looks cool until the animation starts again on frame 1.
already tried to set initial state on the dudes, deleted particle startup cache, disabled cache creation completely, played with the oversampling values..... but the problem still exists.
Iīm on maya5 now, but was the same in 4.5.
any suggestions, pleazzzzze.
cheers, tom :eek:

cavetroll
06-16-2003, 12:46 PM
come on guys. nobody ever ran into such a problem?
any suggestions..... not a single reply....?
sad tom :annoyed:

ME3D
06-18-2003, 06:21 AM
Sorry no soution to your problem as of yet, but so your not sad I am having same problem.

keep in touch. I"ll look into it again soon.

Jozvex
06-18-2003, 06:30 AM
You could try setting a key for those values on the first frame. And maybe on the last frame too, so that they're keyed to stay right.

:hmm: Just an idea.

alexx
06-18-2003, 02:48 PM
the goal weights have an itial state..
you can change values to whatever you like.. but on frame 1 they get their initial state again (which is stored as goalWeightPP0).

to fix that:
go to frame 1
do the changes you want
set initial state for the particle system..
that should be it.

btw.. at least in earlier versions of maya, when setting an initial state on a frame other than 1, messed a lot up and the initial state at frame 1 (and thus creation expressions) do not work anymore..

cheers

alexx

cavetroll
06-22-2003, 03:05 PM
thank you for the suggestions, guys, and sorry for the late reply. (had to rig another character this week)
I finally managed to control the goal weights again. the mistake? I made was that I did set the startFrame for the particles on -10 and somehow the dudes freaked out. so I did rebuild the softBody again and did set my values and initialState on frame 1.
so.... at the moment, another big issue for me is the following. if you successfully want to render your particles and to behave correctly, you have to cache them, right? so in my case, where animation will start at frame 1, I do have to start with the simulation in negative frame range, right? so I have to set the startFrame of the particles to negative something.
the problem is that when I start the simulation, the softBody, which has some gravity assigned, strangely jitters until it comes to frame 1 where it starts to behave correctly.
to see that behaviour you could do the following. get a prim. nurbsSphere. make it a softBody with a goal weight of letīs say 0.6. now add some gravity or another field to the particles. look at the simulation starting on frame 1 and let it simulate from frame -50. you should see the jittering.
what do I miss here? suggestions strongly appreciated.
cheers, tom. :shrug:

wrend
06-23-2003, 05:54 PM
eww, nasty.
this fella may well have bitten on a previous project, now that i see it isolated. we ended up offsetting all, so everything was in positive. i have a feeling there is something else that responds not so happily to negative time also.

this should have its own thread.

alexx
06-23-2003, 06:42 PM
>> ...if you successfully want to render your particles and to behave correctly, you have to cache them, right? ...

hmm.. no basically you should be able to render your particles without having a disk cache..
i sometimes have the strange feeling alias invented the disk cache to solve problems with particle renderign which they were not able to figure out.
i render about 99% of my particles without any caching and run fine..
only sometimes and i can not tell why they wont work without..
usually i only use particle disk cache, when i want to control the time attribute myself by setting keys and/or have the particles run in opposite direction..

about the problem below frame 1: particles have a "start time" which tells maya when to start calculation on them and the default value in each system is 1..
so check for that in your particles and change to your particle starting time.. that works for me ..

cheers

alexx

cavetroll
06-24-2003, 12:33 AM
>> sometimes have the strange feeling alias invented the disk cache to solve problems with particle renderign which they were not able to figure out.
i render about 99% of my particles without any caching and run fine..

chaching particles for me completely makes sense if you want to eliminate any simulation time when rendering. and I think it also is necessary when you want to render on multiple machines.... our your farm...

>> about the problem below frame 1: particles have a "start time" which tells maya when to start calculation on them and the default value in each system is 1..
so check for that in your particles and change to your particle starting time.. that works for me ..


I did set startFrame of the particles to -50 in the particleShape, that is where I want to start my simulation, to get the particles to a resting position just before my character animation starts. I also did set the timeline to -50, but this could be any other value.
Offsetting my animation could be a solution but.... mmhhhh....
I really donīt know at the moment.
what the hell am I missing???? is it that negative time thingy that drives the simulation crazy? even if I create the softbody at frame -50, the particles start at frame 1....
:annoyed: getting tom
maybe I should have a :beer: now...

misterdi
06-25-2003, 12:09 PM
About the start time

I think it has been answer in previous message, if you create your softbody at frame -50, the time attribute in particleShape still use 1 as default.

Set this attribute to -50, it will then start your particle simulation at frame -50

Best regards,

alexx
06-25-2003, 12:42 PM
hmm.. really strange.. have you contacted alias about it?

about rendering and particle disc cache..
i render on 20 machines without cache.. works fine.. but you are right. you dont have to calculate the particles..
but i found that the particle disk caches can slow down rendering as well, since the cache files can become quite huge and when rendering with a lot of machines at once that can become really slow then..

anyway.. sorry. i have no more ideas how to fix the negative frame issue..

cheers

alexx

cavetroll
06-25-2003, 08:59 PM
yeah. letīs close this thread. somehow I have to work around it. thank you anyway, guys.

take care, tom.

GRMac13
05-30-2004, 05:54 PM
I'm having the same problem with Maya 6 and the Bonus Tools' Dynamic Secondary Animation script. The script creates the spline IK and SB particles automatically with a falloff. Unfortunately, there is no way to set the individual goal weights until after the script is run (just a choice between linear, quick and gradual falloff states). I have the same issue as cavetroll in that after I edit the goalPP values in the Component Editor, I get a good playback on the first run, but on the second playback, the values revert back to their inital state. This is extraordinarily frustrating, to say the least. If anyone out there has a good solution, please help. :banghead:

Sanctuary
06-04-2004, 02:06 PM
about rendering and particle disc cache..


disc cache main purpose is to allow render of motion blur on those particles

i think :bounce:

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