Wow, this thread went off the rails quickly. You can, indeed, plug an animCurve into anything with a 'time' attribute, in this case, it would be to the nParticleShape1Cache1.time attribute.
There's a 'Scene Time Warp' feature (look under the Animate menu) in Maya 2015 that seemed to work on nParticle caches for me. It still doesn't handle frame-interpolation properly, but you may be able to crank your subsamples and get what you need. BTW, I think the script you're thinking of is called Time Warper (http://www.creativecrash.com/maya/script/time-warper)? But you guys are all right; Maya is missing the ability to interpolate sub-frames automatically in the nCache format. Bifrost's .bif format does not have this issue, as points/voxels/etc carry their own velocity data. This means you don't have to sample prev/next frames to get motion blur. Adrian -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Tim Leydecker Sent: Wednesday, February 18, 2015 7:51 PM To: [email protected] Subject: Re: OT Maya: ncache hell Hi Adrian, thanks for the explanation of your approach. Yes, that sounds like a lot of work. I was thinking more along the lines of asking Autodesk to implement additional cache editing as a feature, e.g. be able to retime and reanimate existing cached data as if working with a keyframed channel. Either using an animation curve on the time input or even messing with the full data with interpolation between "keyframes", knowing that motionblur will then still work nicely. I would think this could be regarded desireable for working with alembic files, bifrost, volumes, particles, animation, etc. There is a standalone app that let´s you modify particle caches after sim, I can´t remember the name atm... Anyway, asking to get Trax have better interpolation for caches might be interesting, too. Imho, having to decide beforehand how many subsamples/ticks/substeps to store in a cache is a bit of a shot in the dark and can easily bloat files while still not solving the problem of always getting nice motionblur, regardless of shutter settings and lengths that may change later. I´d think there is room for improvement, ideally allowing to cache to sparse data and interpolate for best results. Am 19.02.2015 um 01:41 schrieb Adrian Graham: > I've written scripts that do this: > > - generate a null for each particle emitted > - move the null to the updated particle location on each frame > - keyframe the null after moving it > - rinse and repeat > > So you end up with a big mess of nulls and keyframes, and not much else you > do with them. > > I suppose you could do the above, then kill particle emission, then do it the > other way around; write a runtime expression to emit one particle per null, > and move it where each null is at each frame. This would work at any > sub-frame, as the runtime expression would query the exact position of the > associated null at the current time. > > But that's a real roundabout way of doing this, and you'd quickly bog down > with hundreds or thousands of particles/nulls. > > If you're really interested in doing this, I could try it and record a video > showing you how I did it. > > Adrian > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of Tim Leydecker > Sent: Wednesday, February 18, 2015 3:59 PM > To: [email protected] > Subject: Re: OT Maya: ncache hell > > Hi Adrian, > > would there be a way to plot/bake an nCache to keyframes per particle and > then use the "natural" interpolation happening between keyframes to get > better retiming results? > > One could then always re-export to a new cache? > > If not, that may be an idea to suggest as a feature request? > > E.g. the feature request would be to allow the user to edit any cached data > input in the fcurve editor as keyframe data with all the interpolation > options usually found between two keyframes. > > That shouldn´t be insanely complicate to be pulled off as it would "just" > require to read cache data as keyframes, then interpolate instead of step, no? > > Cheers, > > tim > > > > > Am 18.02.2015 um 20:05 schrieb Adrian Graham: >> Er, let's pretend you guys never saw that... >> >> >> From: Ben Beckett <[email protected]<mailto:[email protected]>> >> Reply-To: >> "[email protected]<mailto:[email protected] >> m>" >> <[email protected]<mailto:[email protected] >> m>> >> Date: Wednesday, February 18, 2015 at 5:19 AM >> To: >> "[email protected]<mailto:[email protected] >> m>" >> <[email protected]<mailto:[email protected] >> m>> >> Subject: Re: Aw: OT Maya: ncache hell >> >> Maya 2016! >> >> On 18 February 2015 at 04:23, Adrian Graham >> <[email protected]<mailto:[email protected]>> wrote: >> Hey guys, the best way to retime nCaches is in the Trax editor. Select the >> cached node and open the editor. You'll see a bar representing the length of >> your cache on disk. You can expand/compress this bar to achieve the retiming >> you desire. You can't ramp-in/ramp-out the speed, unfortunately. Not without >> extremely unpredictable results, that is. >> >> Now it gets tricky, so I recorded a couple of videos (in .swf format) to >> maybe provide a bit of insight: >> >> nCache_retiming_01.swf<https://autodesk.box.com/s/ves0ye66ny9sc0y78a8c >> k8xi8af2zyns> >> nCache_retiming_02.swf<https://autodesk.box.com/s/bxwfnuupxw11fz9tvfr9 >> 4k72djb9fwfv> >> >> Also, as I mentioned at the end of the second video, a suggestion from one >> of our devs here is to goal 'classic' particles to your nParticles >> (post-retiming), cache those out and render them, rather than the nParticles: >> >> You could export it as a classic particle cache (with dynExport) , and then >> create a classic particle shape with exactly the same set of attributes as >> you exported. (which means that you either have to explicitly specify the >> list of PP attrs so that you don't end up with ramp input attrs, or you may >> need to add any extra cached attrs to the classic particle system). >> >> Hope this helps, >> Adrian >> >> From: >> [email protected]<mailto:softimage-bounces@listp >> roc.autodesk.com> >> [mailto:[email protected]<mailto:softimage-bounc >> [email protected]>] On Behalf Of Gerbrand Nel >> Sent: Monday, February 16, 2015 4:59 AM >> To: >> [email protected]<mailto:[email protected] >> Subject: Re: Aw: OT Maya: ncache hell >> >> Ugh.... >> Well thanks for the heads-up. >> G >> On 16/02/2015 11:50, Leo Quensel wrote: >> I've been through this hell. >> Long story short: Do it in Softimage, it is next to impossible to do it >> properly in Maya and it is a buggy mess. >> >> Gesendet: Montag, 16. Februar 2015 um 10:45 Uhr >> Von: "Gerbrand Nel" >> <[email protected]<mailto:[email protected]>><mailto:[email protected] >> <mailto:[email protected]>> >> An: >> [email protected]<mailto:[email protected] >>> <mailto:[email protected]<mailto:[email protected] >> odesk.com>> >> Betreff: OT Maya: ncache hell >> Hey guys >> So I have to re-time my particles in Maya, and no one seems to know >> how to do this properly. >> Do you guys know if I can bring them into softimage, re-time, and then >> re-export the ncache to maya? >> Even if you know how to do it with houdini, please shout! >> Thanks guys >> >> >>
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