Animated alembic curves dont update on render #58704

New Issue

mantissa · 2018-12-04T12:28:11+01:00

mantissa commented

2018-12-04 12:28:11 +01:00

System Information
Operating system: Xubuntu 18.04
Graphics card: Titan X (Pascal)

Blender Version
Broken: 2.80 63ac7c799c

Short description of error
Imported alembic objects with animated hair strands render incorrectly.
The cache doesn't get read properly and no updates happen in between frames when rendering, resulting in a render where the animation is stuck on the first frame of the cache.
Problem persists between Eevee and Cycles. Regular mesh based caches work fine, this only seems to affect imported hair/curves.
Tried animating the frame parameter too, as well as adding a driver, but it doesn't help. Every render is static on the first frame of the cache.

Exact steps for others to reproduce the error

Create hair system
Animate said hair system (dynamics / forces)
Export Hair to Alembic
Import Alembic with hair animation
Hair animation doesn't update on render

alembic-render.zip

**System Information** Operating system: Xubuntu 18.04 Graphics card: Titan X (Pascal) **Blender Version** Broken: 2.80 63ac7c799c8 **Short description of error** Imported alembic objects with animated hair strands render incorrectly. The cache doesn't get read properly and no updates happen in between frames when rendering, resulting in a render where the animation is stuck on the first frame of the cache. Problem persists between Eevee and Cycles. Regular mesh based caches work fine, this only seems to affect imported hair/curves. Tried animating the frame parameter too, as well as adding a driver, but it doesn't help. Every render is static on the first frame of the cache. **Exact steps for others to reproduce the error** - Create hair system - Animate said hair system (dynamics / forces) - Export Hair to Alembic - Import Alembic with hair animation - Hair animation doesn't update on render [alembic-render.zip](https://archive.blender.org/developer/F5810162/alembic-render.zip)

mantissa commented

2018-12-04 12:28:11 +01:00

Added subscriber: @Mantissa

blender-admin commented

2018-12-04 12:28:11 +01:00

#86802 was marked as duplicate of this issue

blender-admin commented

2018-12-04 12:28:11 +01:00

#76901 was marked as duplicate of this issue

blender-admin commented

2018-12-04 12:28:11 +01:00

#49447 was marked as duplicate of this issue

blender-admin commented

2018-12-04 12:28:11 +01:00

#60936 was marked as duplicate of this issue

blender-admin commented

2018-12-04 12:28:11 +01:00

#64424 was marked as duplicate of this issue

blender-admin commented

2018-12-04 12:28:11 +01:00

#65526 was marked as duplicate of this issue

blender-admin commented

2018-12-04 12:28:11 +01:00

#64790 was marked as duplicate of this issue

Jacques Lucke commented

2018-12-04 12:36:35 +01:00

Added subscriber: @JacquesLucke

Sergey Sharybin was assigned by Jacques Lucke

2018-12-04 12:36:35 +01:00

Jacques Lucke commented

2018-12-04 12:36:35 +01:00

I can reproduce that. Sounds depsgraph related, because the Alembic import itself is working fine.

Sergey Sharybin removed their assignment 2018-12-04 14:22:42 +01:00

Sergey Sharybin commented

2018-12-04 14:22:43 +01:00

Added subscribers: @dr.sybren, @Sergey

Sergey Sharybin commented

2018-12-04 14:22:43 +01:00

This isn't a dependency graph problem..

The actual issue is caused by the following facts:

Bevel is only allowed on pre-tessellated curve, while it is still guaranteed to have curve twist and other properties.
Mesh sequence cache is a constructive modifier, which runs on post-tessellation state.

This makes it so bevel is never affected by the curve read from the cache. It kind of appeared to be working in 2.79 because mesh cache modifier was modifying object's splines, which is not only going against all designs we have :( but also was causing 1 frame delay during playback.

Now, with Copy-on-Write in place, cache modifier modifies copied version which gets tossed away after frame finished rendering.

The only proper and reliable solution i can think of here is to support real constructive modifiers for curves, which will operate on splines, and give splines back.

Maybe @dr.sybren will have time to look into proper solution one day. But for now unassigning from myself, since is unlikely i'll be handling this myself in the nearest future.

This isn't a dependency graph problem.. The actual issue is caused by the following facts: - Bevel is only allowed on pre-tessellated curve, while it is still guaranteed to have curve twist and other properties. - Mesh sequence cache is a constructive modifier, which runs on post-tessellation state. This makes it so bevel is never affected by the curve read from the cache. It *kind of* appeared to be working in 2.79 because mesh cache modifier was modifying object's splines, which is not only going against all designs we have :( but also was causing 1 frame delay during playback. Now, with Copy-on-Write in place, cache modifier modifies copied version which gets tossed away after frame finished rendering. The only proper and reliable solution i can think of here is to support real constructive modifiers for curves, which will operate on splines, and give splines back. Maybe @dr.sybren will have time to look into proper solution one day. But for now unassigning from myself, since is unlikely i'll be handling this myself in the nearest future.

Brecht Van Lommel commented

2019-06-05 13:30:27 +02:00

Added subscriber: @NizarAmous

Brecht Van Lommel commented

2019-06-05 13:31:18 +02:00

Added subscriber: @amandas

Brecht Van Lommel commented

2019-06-18 18:15:43 +02:00

Added subscribers: @akifdur, @brecht

Brecht Van Lommel commented

2019-07-03 19:31:12 +02:00

Added subscribers: @DanielBystedt, @ZedDB

Brecht Van Lommel commented

2019-07-03 19:42:47 +02:00

Added subscribers: @AlexanderWeide, @kevindietrich

Sybren A. Stüvel commented

2019-08-22 18:05:39 +02:00

I suspect that solving this properly requires #69046.

Philipp Oeser commented

2020-02-07 15:40:01 +01:00

Added subscriber: @lichtwerk

Philipp Oeser commented

2020-02-07 15:40:01 +01:00

@dr.sybren: will tag as Known Issue (or is Design preferred?)

@dr.sybren: will tag as `Known Issue` (or is `Design` preferred?)

Steffen Knoesgaard commented

2020-05-05 18:17:31 +02:00

Added subscriber: @steffenk

Dmitry commented

2020-05-20 10:59:52 +02:00

Added subscriber: @DimaM

Sybren A. Stüvel commented

2020-05-22 09:15:14 +02:00

Closed as duplicate of #76901

Sybren A. Stüvel closed this issue

2020-05-22 09:15:14 +02:00

Sybren A. Stüvel commented

2020-05-25 12:48:37 +02:00

Changed status from 'Duplicate' to: 'Confirmed'

Sybren A. Stüvel reopened this issue

2020-05-25 12:48:37 +02:00

Sybren A. Stüvel commented

2020-05-25 12:48:58 +02:00

Added subscribers: @AtomP, @dfelinto

Robin Hawkes commented

2020-08-15 14:31:55 +02:00

Added subscriber: @Robin-Hawkes

Bryson Adams commented

2021-02-22 06:38:48 +01:00

Added subscriber: @thuskodesign

Philipp Oeser commented

2021-03-22 12:40:28 +01:00

Added subscriber: @MaskerGladys

nizar amous commented

2021-07-09 19:43:35 +02:00

Hello, i just found a workaround for anyone needing this feature, I'm being able to render curves exported from houdini, im using the alembic as input in geonodes and then rendering the geo node object, but i had a few crashes but i could render a frame sequences with this setup

Hello, i just found a workaround for anyone needing this feature, I'm being able to render curves exported from houdini, im using the alembic as input in geonodes and then rendering the geo node object, but i had a few crashes but i could render a frame sequences with this setup ![image.png](https://archive.blender.org/developer/F10218411/image.png)

Dr Formalyst commented

2021-11-23 23:56:52 +01:00

Added subscriber: @dr_formalyst

Dr Formalyst commented

2021-11-23 23:56:52 +01:00

@NizarAmous thanks for the solution, however, as of version 3.0.0 2021-11-08 this workaround is no longer working. are there any other possible workarounds anyone is aware of? thanks!

Andreu Pellisa commented

2022-01-06 10:30:12 +01:00

Added subscriber: @andre1

Andreu Pellisa commented

2022-01-06 10:30:12 +01:00

I was having the same problem and the solution I found was export it from blender as alembic and check the option "Curves as Mesh" and reimported it and working nice!
Hope someone can found this solution too!

I was having the same problem and the solution I found was export it from blender as alembic and check the option "Curves as Mesh" and reimported it and working nice! Hope someone can found this solution too!

Dr Formalyst commented

2022-01-06 14:12:51 +01:00

Thanks @andre1 this is good to know (although in my case I'm exporting from Houdini so this is not an option).

Stefan Mayr commented

2022-01-24 14:53:22 +01:00

Added subscriber: @Dabreiss

Stefan Mayr commented

2022-01-24 14:53:22 +01:00

uuuh, really hope this issue is not being forgotten,, unfortunately I have to bring objects back and forth from and to Maya (I know, I'm a traiter, hahaha) and with this limitation, unfortunately I can't use blender in certain cases

Stefan Mayr commented

2022-01-28 11:20:15 +01:00

In #58704#1283732, @andre1 wrote:
I was having the same problem and the solution I found was export it from blender as alembic and check the option "Curves as Mesh" and reimported it and working nice!
Hope someone can found this solution too!

hey, when I try to export curve as mesh, it only exports the vertices and now edge lines. Really need this to get working, would appreciate any help big time

> In #58704#1283732, @andre1 wrote: > I was having the same problem and the solution I found was export it from blender as alembic and check the option "Curves as Mesh" and reimported it and working nice! > Hope someone can found this solution too! hey, when I try to export curve as mesh, it only exports the vertices and now edge lines. Really need this to get working, would appreciate any help big time

BRUNO RANTIN PO commented

2022-03-03 20:53:59 +01:00

Added subscriber: @brurpo

BRUNO RANTIN PO commented

2022-03-03 20:53:59 +01:00

Is this really forgotten for over four years?
This is a huge problem

Is this really forgotten for over four years? This is a huge problem

Stefan Mayr commented

2022-03-04 11:22:30 +01:00

I very much agree on this. Blender undergoes this massive growth, which is plane amazing and thankfully due to it's versatility there is always a workaround for pretty much anything. In case of alembic curves, I cached them out as pc2 and added thickness via geometry nodes post mesh cache modifier. However fundamentals like this maybe shouldn't be left behind imho

Kévin Dietrich commented

2022-03-04 14:03:55 +01:00

In #58704#1316854, @brurpo wrote:
Is this really forgotten for over four years?
This is a huge problem

A new implementation of curves objects is currently ongoing, which will among other things allow to properly support Alembic I/O. The current plan is to get this ready for Blender 3.2.

As a teaser, here's a final render with the new implementation of the file in this report:
0001-0100.mp4

> In #58704#1316854, @brurpo wrote: > Is this really forgotten for over four years? > This is a huge problem A new implementation of curves objects is currently ongoing, which will among other things allow to properly support Alembic I/O. The current plan is to get this ready for Blender 3.2. As a teaser, here's a final render with the new implementation of the file in this report: [0001-0100.mp4](https://archive.blender.org/developer/F12897082/0001-0100.mp4)

Stefan Mayr commented

2022-03-05 09:14:22 +01:00

That is amazing news, thank you very much for the update

Ahmed Hindy commented

2022-04-02 23:57:34 +02:00

Added subscriber: @ahmed.hindy96

Ahmed Hindy commented

2022-04-02 23:57:34 +02:00

any updates on this? any branch build to try it on?

Kévin Dietrich commented

2022-04-04 14:44:40 +02:00

In #58704#1334168, @ahmed.hindy96 wrote:
any updates on this? any branch build to try it on?

There is no branch for it, but if you would like to try you can apply the following patches in order :

Specific details are in the patches descriptions.

> In #58704#1334168, @ahmed.hindy96 wrote: > any updates on this? any branch build to try it on? There is no branch for it, but if you would like to try you can apply the following patches in order : * [D14484: Cleanup: Alembic, use a structure to pass parameters](https://archive.blender.org/developer/D14484) * [D11591: Alembic: import arbitrary attributes](https://archive.blender.org/developer/D11591) * [D11592: Alembic/USD: use geometry sets to import data](https://archive.blender.org/developer/D11592) Specific details are in the patches descriptions.

Ahmed Hindy commented

2022-04-04 19:03:21 +02:00

yeah I barely can use python lol, I will wait till the 3 patches get merged into master or a branch of their own

Jimmy Gunawan commented

2022-04-22 06:14:15 +02:00

Added subscriber: @BlenderSushiGuy

Jimmy Gunawan commented

2022-04-22 06:14:15 +02:00

I can confirm 22 April 2022, the Alembic Curve bake out still does not animate or moving forward during render using Blender 3.1.2 and 3.2. Will wait for few days / next update....

Kévin Dietrich commented

2022-04-22 06:16:26 +02:00

There is no need to test, you can check the status of D11592: Alembic/USD: use geometry sets to import data, once this is closed and marked as committed, then you can test.

There is no need to test, you can check the status of [D11592: Alembic/USD: use geometry sets to import data](https://archive.blender.org/developer/D11592), once this is closed and marked as committed, then you can test.

Dmitry commented

2022-06-30 21:54:48 +02:00

Removed subscriber: @DimaM

Paul Golter commented

2022-07-20 11:20:11 +02:00

Added subscriber: @paulgolter

Paul Golter commented

2022-07-20 11:20:11 +02:00

Hey for those looking for a hacky workaround to get animated cuves in to Blender from a software package such as Houdini as long as D11592 is not merged yet, checkout this thread: how-to-render-alembic-curves-hairs-from-houdini-with-this-hack

Hey for those looking for a hacky workaround to get animated cuves in to Blender from a software package such as Houdini as long as [D11592](https://archive.blender.org/developer/D11592) is not merged yet, checkout this thread: [how-to-render-alembic-curves-hairs-from-houdini-with-this-hack](https://devtalk.blender.org/t/how-to-render-alembic-curves-hairs-from-houdini-with-this-hack/24945)

孙传祥 commented

2022-12-19 15:00:40 +01:00

Added subscriber: @amasun

孙传祥 commented

2022-12-19 15:00:40 +01:00

In #58704#1283732, @andre1 wrote:
I was having the same problem and the solution I found was export it from blender as alembic and check the option "Curves as Mesh" and reimported it and working nice!
Hope someone can found this solution too!

I use your methord, it works at least. Thanx

> In #58704#1283732, @andre1 wrote: > I was having the same problem and the solution I found was export it from blender as alembic and check the option "Curves as Mesh" and reimported it and working nice! > Hope someone can found this solution too! I use your methord, it works at least. Thanx

Philipp Oeser removed the

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Animated alembic curves dont update on render #58704