Play speed time bend information out of date

[JD3D_CGI]

https://docs.chaosgroup.com/display/...Time-Scale,etc.

Man, I'd really love to know exactly what to do do play my simulation backwards and gradually slow it down and pause...

So I simuluted soemthign that needs ti play backwards and slow down then stop..

none of the following help really applies as the command shave chnaged

• Enable Velocity export in the Output rollout. This channel is necessary for resimulation.
• Simulate your base simulation.
• When the simulation finishes, you can adjust your Time bend controls from the Input rollout. You can change your play speed, set it to loop mode or animate the play speed using the direct cache index mode.
• Do not change any settings in the Dynamics rollout if you want to get a correct Time Bend Resimulation. You can experiment, of course, but results will typically have flickering or distorted playback.
• From the Resimulation rollout, enable Grid Resimulation and enable Use Time Bend Controls. You can increase the Amplify Resolution or leave it at 0. You can also add wavelet turbulence, if the Wavelet channel was exported in the base simulation.
• If Play speed in the Input rollout is a constant value, use 3ds Max's 'Re-Scale time' option to stretch the animations in the scene so that they match your speed. If you want a Play Speed of 0.2, scale the scene time 1/0.2 = 5 times.
• You can choose between two methods of Time Bend in the Resimulation rollout depending on the result you need. Note that both methods work best for simulations with Steps Per Frame set to a value of 1;
  • The General-Purpose method can deal with all kinds of play speeds - both above and below 1, as well as playing backwards. This method runs fast, but may produce some flickering or motion jitter.
  • The Slow Down method works well only when your play speed is between 0 and 1, but will provide smooth playback without jittering or flicker. This method may produce more dissipation, so it's good to combine it with Multi-pass advection for fire/smoke.
• Disable all unused output channels before starting the Resimulation from the No-Export Channels option in the Resimulation rollout. This will reduce the cache file size and speed up the resimulation.

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[Svetlin.Nikolov]

Hey,

Are you simulating liquids or fire/smoke? All of these instructions are needed for fire/smoke, so if you are simulating liquids, you just need to go to the Input rollout and change the settings there.

Cheers!

[Svetlin.Nikolov]

Just updated the docs too...

[JD3D_CGI]

https://www.dropbox.com/s/k3d4xx9x7i...ent_6.mp4?dl=0

So I have use the cache index mode of input to slow down and play a clip backwards (which was hard to get my head around).

If you look at the mixed ink shooting out of the can at around 5 seconds in, it's flickering incredibly - and that is render with BF+BF

https://docs.chaosgroup.com/display/...Time-Scale,etc.

^^^ this document tells me I need to re-sim - except that all of the instructions it gives for resimulation options do not exist.

I just want to play the animation back smoothly.

Any (quick) help would be appreciated as I need to finish this today!

You can see the relevant options I have onthe attached image.

At the minute I feel like I should just check "reimulate" and then hit simulate? - there is no button to "simulate"

it's confusing, and the docs are out of date and therefore contradictory!

How do I smooth that out please!
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[JD3D_CGI]

(I am just simulating liquid by the way) - notably using the RGB channels to separate out colour
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[flipbook]

You are using liquid .. it is the easiest thing in the world to retime. Output with velocity, set a play speed or cache index (keyed) .. job done

[JD3D_CGI]

You are using liquid .. it is the easiest thing in the world to retime. Output with velocity, set a play speed or cache index (keyed) .. job done

OK, but that doesn't seem to be what the old information files say - and it doesn't solve that flickering colouring in the video.

The liquid colour just randomly changes.

https://www.dropbox.com/s/k3d4xx9x7i...ent_6.mp4?dl=0


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[Svetlin.Nikolov]

Hey,

Phoenix has two simulators - liquid and fire/smoke. They have different options. This info refers to the fire/smoke simulator: https://docs.chaosgroup.com/display/...Time-Scale,etc

If you see the docs talking about options you don't have, either you have an old Phoenix version, or the docs are talking about the other simulator type.

Now onto the issue - the RGB grid channel is not getting reconstructed from particle RGB when retiming a liquid simulation. This needs to be implemented, ETA next week.

However, you should be able to work around this using the Particle Texture of Phoenix 3.11 instead of the Grid Texture for the RGB of the liquid mesh material. You just need to substitute the Phoenix Grid Texture with a Particle Texture in the mesh material, pick the liquid particles, enable Color From Particle Channel and pick the RGB liquid particle channel. After that, you might need to increase the Particle Area Radius if you get gray or black spots in the liquid.

Hope this help, cheers!

[JD3D_CGI]

Thanks Svetlin.

Will that require a re simulation?

[JD3D_CGI]

And when you say "next week" how late are we talking?

I genuinely think my client is thinking is having me murdered

[Svetlin.Nikolov]

Hey,

Nope, adjusting the Input controls does not require simulating again - you have already adjusted those, so the only thing left is to exchange the grid tex for a particle tex so you don't have to wait until next week. Have you tried that?

Cheers!

[JD3D_CGI]

Thanks for the help, but I don't fully get why it isn't working.

I was away for the weekend and got back around 11pm - just tried to do what you said.

First I tried to choose the particle system but it said I was creating a dependency loop, so I copied the system and chose that, and I selected the RGB channel but I am just getting one colour; it's not doing any blending at all.

You have all the data, could you show me how it's supposed to connect up please? do I still need to colour correction nodes? did you get it working? you can see the setup I have from the screenshot.




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[Svetlin.Nikolov]

Hey, we're starting to look at the scene right now and will update you when we know more.

[ben_hamburg]

hey, just jumping in here, since I will also have to do retiming on liquid simulations...does that mean its not possible to resimulate retimed liquids or that its just necessary in specific situations?

For liquids, changing the Time Bend controls is usually enough to re-time a simulation.

And if so...what would those specific situation be?

For example: I have a high speed water stream hitting a surface and need to retime it to 1/5th play speed, once the stream hits the surface.
I´m gonna run a test over night, but maybe you can already clear that up.

[Svetlin.Nikolov]

Okay guys, here it goes, as brief as I can put it:


Liquids are retimed from the Input rollout only.

Fire/smoke can be retimed from the Input rollout, and if you are not happy with the result, you can run a Time Bend Resimulation.