Foam particles black?

[Truffi]

Hi

Since the installation of the 25691 Nightly Built I seem not to be able to render Foam particles properly anymore. They are in the alpha channel but in the RGB they're just shaded black.
Before I had the official 2.2 version of the plugin installed.
Sorry if it had been brought up before.


Is there any guide on how to tweak a nice motion blur to the particle rendering?

Sncerly,
Chris

[Ivaylo Katev]

a fast test made here does not show any problems.
there is one possibility, you may have downloaded wrong build, the defscanline builds are producing black atmosphere objects unless you have a geometry in background. if this is not the case, i would ask you for the scene to investigate the problem.

[Truffi]

Yes, installing the Vray Version helped! The particles are now shown like expected.

With the current version, why is it not possible anymore to keyframe timescale?

[Svetlin.Nikolov]

If you are using it, we will turn it back on for the next nightly - the grid solver does not behave well with animated timescale, but the particles can actually still use this.

[Truffi]

It would be awesome! I am using it for both particles and smoke, however I have indeed experienced some issues with liquid behavior if the timescale value was set lower than 0,5.

Currently I have issues with foam particles' motionblur, it is preprocessing quite long but does not show in the render - maybe it has to do with the fact the simulation does have a timescale of 0,2?

However it would still be very useful to have animated timescale. So turning it back on would be much appreciated!


What is the future solution for slowed down effects? Is this supposed to be done by adjusting the playspeed? So far I avoided to lower the playspeed of a simulation because of blending effects.

[Svetlin.Nikolov]

For fire/smoke we recommend re-simulation for retiming (check http://docs.chaosgroup.com/display/P...time-scale,etc.).
For particles and FLIP liquids it will be the simulation time scale indeed.

[Ivaylo Katev]

it's a long story, but in few words the time scale animation involves non integer steps per frame. this feature seems to produce significant count of problems and bugs and we are trying to replace it with better alternatives.
non integer steps per frame will be not supported in the flip solver for sure. the animated timescale effects will be achieved by simulations with spf=1 combined with animated play speed.

[Truffi]

Thanks for this clarification. The timebend under the Re-Sim panel works fantastic for smoke. However what is the workflow when trying to get point particles and smoke snychronized?

The practical problem when using the TimeBend for particles is that it seem not to be able to start in the middle of an existing sim.

So after I simulated my Smoke with particles and adjusted the Direct Frame Index in the Input pannel, I re-simulate with timebend checked. My Direct Frame playback starts at frame 50 at 0 in the timeline and ends at 75 at 100 in the timeline. I would expect it to re-simulate 25 frames and map it to 100 frames, so four times slower than the original speed. It works for the smoke, but unforuntally for partciles the resim starts at frame 0 again. It does slow down particle movement to one forth the speed but it does start the simulation from the beginning.

I am using version 25691. The resim output is set to go into a seperate folder. I am a little bit lost and wondering at what step things went wrong..
The only solution I can think of is to duplicate the sim cage and have one display the re-simulated smoke and the second display the particles of the base sim, which are simply re-timed in the Input panel.

[Svetlin.Nikolov]

Yes, that workaround should do the trick - particle retime is still not implemented in the nightlies. If you can afford to wait for a couple of days, we could try to get it working?

[Truffi]

There is no time pressure on this for me and the workaround is good enough for now. Thankyou very much for the offer to get the particle timebend implemented right now! However I bet you have heaps of other priorities. Just saying it would be good to have a more obvious timebend workflow in the next future release. I appreciate your help.

[Svetlin.Nikolov]

Oh yes, surely it will be implemented for the next release. The time bend resim currently stands in the nightly as a proof of concept, but there will be more work on it before it's officially out.