Liquid simulation, cache type "Replay", doesn't recognize objects created after Domain creation, doesn't update #75850

New Issue

Nicola De Mitri · 2020-04-17T22:44:05+02:00

Nicola De Mitri commented

2020-04-17 22:44:05 +02:00

System Information
Operating system: Ubuntu 18.04
Graphics card: irrelevant

Blender Version
Broken: 2.83 Beta 8cb10c124e 17 Apr 2020

Short description of error
Under cache type "Replay" (which appears to be the new default) the domain only takes into account fluid objects that were created before creating the domain!

Exact steps for others to reproduce the error

Creating domain first: Doesn't work

Default file. (Activate X-Ray)
Default cube: Scale up by 2. Add Physics > Fluid > Domain > Type: Liquid
Add new cube at origin (inside the initial cube).
Add: Fluid > Flow > Type Liquid
Right arrow 10 times
- Expected: FLIP particles pouring from the inner cube
- Actual: Nothing happens

Creating flow/effectors first: Kind of works

Default file. (Activate X-Ray)
Default cube: Add: Fluid > Flow > Type Liquid
Add new cube at origin. Scale up by 2.
Add: Fluid > Domain > Type Liquid
Right arrow 10 times (works)

However in this situation I can't make use of the "Replay" advantages because any change I make to the scene won't be taken into account (unless I change cache location)

**System Information** Operating system: Ubuntu 18.04 Graphics card: irrelevant **Blender Version** Broken: 2.83 Beta 8cb10c124efe 17 Apr 2020 **Short description of error** Under cache type "Replay" (which appears to be the new default) the domain only takes into account fluid objects that were created before creating the domain! **Exact steps for others to reproduce the error** Creating domain first: Doesn't work - Default file. (Activate X-Ray) - Default cube: Scale up by 2. Add Physics > Fluid > Domain > Type: Liquid - Add new cube at origin (inside the initial cube). - Add: Fluid > Flow > Type Liquid - Right arrow 10 times - Expected: FLIP particles pouring from the inner cube - Actual: Nothing happens Creating flow/effectors first: Kind of works - Default file. (Activate X-Ray) - Default cube: Add: Fluid > Flow > Type Liquid - Add new cube at origin. Scale up by 2. - Add: Fluid > Domain > Type Liquid - Right arrow 10 times (works) However in this situation I can't make use of the "Replay" advantages because any change I make to the scene won't be taken into account (unless I change cache location)

Nicola De Mitri commented

2020-04-17 22:44:05 +02:00

Added subscriber: @NicolaSap

Ankit Meel commented

2020-04-18 17:05:48 +02:00

Added subscriber: @ankitm

Ankit Meel commented

2020-04-18 17:05:48 +02:00

Changed status from 'Needs Triage' to: 'Needs User Info'

Ankit Meel commented

2020-04-18 17:05:48 +02:00

Creating domain first: Doesn't work

I can see the particles, & I followed the steps in order. I'm using 221a7002a9
Please share a blend file for both cases.

> Creating domain first: Doesn't work I can see the particles, & I followed the steps in order. I'm using 221a7002a9 Please share a blend file for both cases.

Nicola De Mitri commented

2020-04-18 20:17:50 +02:00

I don't have my building environment ready, so I downloaded last night's builds (76b3aac802). I still reproduce the error.

However, if I save and reopen, the particles now show correctly (but the cache is empty). This is an interesting finding, by the way. However, it means that I can't share a file to demonstrate, because opening from file is effectively a workaround.

I'll show a video instead:
Peek 2020-04-18 19-15.mp4

I don't have my building environment ready, so I downloaded last night's builds (76b3aac802f9). I still reproduce the error. However, if I save and reopen, the particles now show correctly (but the cache is empty). This is an interesting finding, by the way. However, it means that I can't share a file to demonstrate, because opening from file is effectively a workaround. I'll show a video instead: [Peek 2020-04-18 19-15.mp4](https://archive.blender.org/developer/F8482152/Peek_2020-04-18_19-15.mp4)

Nicola De Mitri commented

2020-04-18 20:20:59 +02:00

PS: saving alone doesn't help, nor does saving at the very beginning (which would be a problem if cache was somewhere in //, which it isn't). I have to save then re-open to obtain a workaround

PS: saving alone doesn't help, nor does saving at the very beginning (which would be a problem if cache was somewhere in `//`, which it isn't). I have to save then re-open to obtain a workaround

Ankit Meel commented

2020-04-19 08:22:57 +02:00

Please try after moving the blender preferences folder outside so that blender starts fresh & you have your preferences safe.
I used 1f1520a045.
Still cannot redo. Making the inner cube flow | liquid shows particles.

Screen Recording 2020-04-19 at 11.47.54.mov

Please try after moving the blender preferences folder outside so that blender starts fresh & you have your preferences safe. I used 1f1520a045. Still cannot redo. Making the inner cube flow | liquid shows particles. [Screen Recording 2020-04-19 at 11.47.54.mov](https://archive.blender.org/developer/F8482926/Screen_Recording_2020-04-19_at_11.47.54.mov)

Nicola De Mitri commented

2020-04-19 13:56:58 +02:00

I've repeated with fresh preferences and still no luck :(

Ankit Meel commented

2020-04-19 14:07:17 +02:00

Changed status from 'Needs User Info' to: 'Needs Triage'

Richard Antalik commented

2020-04-20 14:44:32 +02:00

Added subscriber: @iss

Richard Antalik commented

2020-04-20 14:44:32 +02:00

@NicolaSap does this happen if you modify domain content and press shift + right key?

It seems that if you move playhead my mouse, domain won't update

@NicolaSap does this happen if you modify domain content and press shift + right key? It seems that if you move playhead my mouse, domain won't update

Germano Cavalcante commented

2020-04-21 12:48:25 +02:00

Added subscriber: @mano-wii

Germano Cavalcante commented

2020-04-21 12:48:25 +02:00

Changed status from 'Needs Triage' to: 'Confirmed'

Germano Cavalcante commented

2020-04-21 12:48:25 +02:00

I can confirm that there is some strange behavior.
Although there are workarounds (for example updating the cache) this should not happen.

So I am confirming it as a bug.

I can confirm that there is some strange behavior. Although there are workarounds (for example updating the cache) this should not happen. So I am confirming it as a bug.

Nicola De Mitri commented

2020-04-24 14:24:35 +02:00

The issue I was encountering seems to be fixed in the latest builds (d712f1f83a)

The issue I was encountering seems to be fixed in the latest builds (d712f1f83af8)

Nicola De Mitri commented

2020-04-24 14:31:33 +02:00

What is still true, however, is that there isn't a way to invalidate a "Replay" cache once the simulation has started. If I cache the first 3 frames, then I add/remove/move some element, playing the animation still works using the original flows and effectors. In the other simulation engines that allow "Replay" modes (e.g. rigid body, cloth) going back to frame 0 and re-starting the animation would invalidate and recompute the cache, if something has changed in the meanwhile.

I don't know if this (↑) is the "strange behavior" Germano is talking about. If it is, then this Task should probably stay open. If it's not, then probably this Task can be closed and my other concern can be ticketed separately (can/should I do it or is it considered a feature request?)

What is still true, however, is that there isn't a way to invalidate a "Replay" cache once the simulation has started. If I cache the first 3 frames, then I add/remove/move some element, playing the animation still works using the original flows and effectors. In the other simulation engines that allow "Replay" modes (e.g. rigid body, cloth) going back to frame 0 and re-starting the animation would invalidate and recompute the cache, if something has changed in the meanwhile. I don't know if this (↑) is the "strange behavior" Germano is talking about. If it is, then this Task should probably stay open. If it's not, then probably this Task can be closed and my other concern can be ticketed separately (can/should I do it or is it considered a feature request?)

Ankit Meel commented

2020-04-25 13:19:24 +02:00

In the other simulation engines that allow "Replay" modes (e.g. rigid body, cloth) going back to frame 0 and re-starting the animation would invalidate and recompute the cache, if something has changed in the meanwhile.

As @iss also said above, shift right or going to the starting frame updates the cache.
If there's isn't anything else @mano-wii you noticed, closing it should be fine.

> In the other simulation engines that allow "Replay" modes (e.g. rigid body, cloth) going back to frame 0 and re-starting the animation would invalidate and recompute the cache, if something has changed in the meanwhile. As @iss also said above, shift right or going to the starting frame updates the cache. If there's isn't anything else @mano-wii you noticed, closing it should be fine.

Nicola De Mitri commented

2020-04-25 13:26:35 +02:00

going to the starting frame updates the cache

This is not true for me!

Peek 2020-04-25 12-24.mp4

shift right

This neither

Peek 2020-04-25 12-25.mp4

(d712f1f83a builds from yesterday)

> going to the starting frame updates the cache This is not true for me! [Peek 2020-04-25 12-24.mp4](https://archive.blender.org/developer/F8494272/Peek_2020-04-25_12-24.mp4) > shift right This neither [Peek 2020-04-25 12-25.mp4](https://archive.blender.org/developer/F8494273/Peek_2020-04-25_12-25.mp4) (d712f1f83af8 builds from yesterday)

Ankit Meel commented

2020-04-25 13:32:48 +02:00

Does the effector have some thickness ?

Nicola De Mitri commented

2020-04-25 13:41:44 +02:00

Yes, it's a scaled cube. It doesn't have "Surface thickness" but that's not required. Indeed, it works just fine if I manually delete the cache and restart

But Blender won't invalidate the cache on its own. The problem is with the cache, not with my scene settings.

Yes, it's a scaled cube. It doesn't have "Surface thickness" but that's not required. Indeed, it works just fine if I manually delete the cache and restart ![image.png](https://archive.blender.org/developer/F8494296/image.png) But Blender won't invalidate the cache on its own. The problem is with the cache, not with my scene settings.

Nicola De Mitri commented

2020-04-25 14:33:52 +02:00

Changed status from 'Confirmed' to: 'Resolved'

Nicola De Mitri closed this issue

2020-04-25 14:33:52 +02:00

Nicola De Mitri self-assigned this 2020-04-25 14:33:52 +02:00

Nicola De Mitri commented

2020-04-25 14:33:52 +02:00

It's been pointed out, in the chat, that the shift in focus of this Task may be confusing.

Since the issue that gives the title to this Task is now solved, this task can be closed as Resolved.

I've opened another Task (#76095) for the bugs that emerged after the original bug.

It's been pointed out, in the chat, that the shift in focus of this Task may be confusing. Since the issue that gives the title to this Task is now solved, this task can be closed as Resolved. I've opened another Task (#76095) for the bugs that emerged after the original bug.

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Liquid simulation, cache type "Replay", doesn't recognize objects created after Domain creation, doesn't update #75850