Hair Dynamics: simulation doesn't work depending on smooth/flat shaded surfaces (and nvidia gpus?) #68681

New Issue

Imre Varga · 2019-08-15T09:09:37+02:00

Imre Varga commented

2019-08-15 09:09:37 +02:00

System Information
Operating system: Windows 10
Graphics card: RTX 2070 QMax

Blender Version
Broken: v 2.80
Worked: (optional)

hair dynamics doesn't work, hair stuck in place, doesn't follow the mesh

Exact steps for others to reproduce the error

build simplest possible model with hair dynamics
add simple animation
with hair dynamics disabled: hair follows mesh
with hair dynamics enabled: hair just stays behind and stretches to the mesh
changing settings, clearing cash ... all to no avail

190814_test_hair_dynamics.blend

**System Information** Operating system: Windows 10 Graphics card: RTX 2070 QMax **Blender Version** Broken: v 2.80 Worked: (optional) hair dynamics doesn't work, hair stuck in place, doesn't follow the mesh **Exact steps for others to reproduce the error** - build simplest possible model with hair dynamics - add simple animation - with hair dynamics disabled: hair follows mesh - with hair dynamics enabled: hair just stays behind and stretches to the mesh - changing settings, clearing cash ... all to no avail [190814_test_hair_dynamics.blend](https://archive.blender.org/developer/F7665517/190814_test_hair_dynamics.blend) ![190814_hair_dynamics.png](https://archive.blender.org/developer/F7665506/190814_hair_dynamics.png)

Imre Varga commented

2019-08-15 09:09:37 +02:00

Added subscriber: @imrevarga

blender-admin commented

2019-08-15 09:09:37 +02:00

#84358 was marked as duplicate of this issue

blender-admin commented

2019-08-15 09:09:37 +02:00

#73370 was marked as duplicate of this issue

blender-admin commented

2019-08-15 09:09:37 +02:00

#71460 was marked as duplicate of this issue

blender-admin commented

2019-08-15 09:09:37 +02:00

#68737 was marked as duplicate of this issue

Philipp Oeser commented

2019-08-15 09:33:33 +02:00

Added subscriber: @lichtwerk

Philipp Oeser commented

2019-08-15 09:33:33 +02:00

#67958 might be related, will check

Philipp Oeser commented

2019-08-15 09:38:47 +02:00

Cannot really reproduce, if I rebake (or change any setting -- which also clears the cache), everything is fine...

@imrevarga : does Delete Bake, then Bake fix it for you?

Cannot really reproduce, if I rebake (or change any setting -- which also clears the cache), everything is fine... @imrevarga : does `Delete Bake`, then `Bake` fix it for you?

Imre Varga commented

2019-08-15 10:28:44 +02:00

I tried everything, bake, delete bake, bake again, go in and out of edit mode, change settings ... just doesn't work. There is a suspicion that it might be related to the RTX2070 or the latest driver of that since I also get the following issues:

jiggle bones work in viewport, but don't render
regular erratic blue screens while using blender with a VIDEO_TDR_FAILURE message

I tried everything, bake, delete bake, bake again, go in and out of edit mode, change settings ... just doesn't work. There is a suspicion that it might be related to the RTX2070 or the latest driver of that since I also get the following issues: - jiggle bones work in viewport, but don't render - regular erratic blue screens while using blender with a VIDEO_TDR_FAILURE message

Joselu commented

2019-08-15 12:36:37 +02:00

Added subscriber: @Xeluaxeman

Joselu commented

2019-08-15 12:36:37 +02:00

I had similar unstable issues with windows 10 v1903 and gtx 1070.

I will reinstall and also try latest versions again to pinpoint the problem.

Probably a nvidia gpu driver problem as you say.
(I have the latest installed....)

I had similar unstable issues with windows 10 v1903 and gtx 1070. I will reinstall and also try latest versions again to pinpoint the problem. Probably a nvidia gpu driver problem as you say. (I have the latest installed....)

Joselu commented

2019-08-15 12:40:28 +02:00

Forgot to say that in linux ubuntu os did not find issues and seems to be more stable and faster with everything.

Windows always giving headaches...

Forgot to say that in linux ubuntu os did not find issues and seems to be more stable and faster with everything. Windows always giving headaches...

Joselu commented

2019-08-15 14:50:37 +02:00

I installed previous nvidia driver but the bug persists in all windows 10 64bit Blender versions.

If you try to play hair in an object with Shade Smooth instead of Shade Flat it will NOT run.

I am also having unstable behaviour when interactive render in cycles sometimes.

Blender seems unstable with dynamics in general.

I installed previous nvidia driver but the bug persists in all windows 10 64bit Blender versions. If you try to play hair in an object with Shade Smooth instead of Shade Flat it will NOT run. I am also having unstable behaviour when interactive render in cycles sometimes. Blender seems unstable with dynamics in general.

Garry R. Osgood commented

2019-08-16 02:44:34 +02:00

Added subscriber: @grosgood

Garry R. Osgood commented

2019-08-16 02:44:34 +02:00

@imrevarga
Similar to @lichtwerk, I can confirm your observations up to, but excluding, your last step:

changing settings, clearing cash ... all to no avail

I do not have that issue here. Changing settings clears cache. Baking sucessfully caches a new simulation that shows none of the issues you report. Particulars:

I temporarily cleared the Dynamic Hair checkbox, which cleared the cache loaded with your file.
Then, probably unnecessarily, ran the animation with Dynamic Hair unchecked, just to satisfy myself that there were zero frames cached in memory.

Finally, I restored the Dynamic Hair checkbox and baked all 100 frames. Blender reported a cache of 100 frames, consuming about 25.2 MB

This gave me a clean animation. See #68681.mkv Compare with the animation made with your original file and its original cached data. See T68681_original_cache.mkv
To make these animations, I modified your file slightly: I put a damped track constraint on the camera so that it would follow the head.

There does seem to be something incorrect about the cached simulation in your posted file. The simulation is cut short to 68 frames, and the system here had trouble restarting the simulation at frame 69, given your original cached data (the hair explodes). At the end of the run, Blender reports inexact data from frame 0 - not a good sign. All that notwithstanding, fully clearing the cache and restarting
the simulation from the first frame produced a complete and viable simulation - at least on my hardware.

This suggests to me that there is some aspect of your system that is corrupting the caching of your simulation -- every time -- likely from the very first frame.

In light of that, please also consider posting your system information. When in Blender, go to the help menu and choose "Save System Info" Post the resulting file here. Thank you!
system-info.txt (My system information, for reference)
#68681.mkv #68681.mkv - animation from regenerated cache
T68681_original_cache.mkv T68681_original_cache.mkv - animation from original cached data.

@imrevarga Similar to @lichtwerk, I can confirm your observations up to, but excluding, your last step: > changing settings, clearing cash ... all to no avail I do not have that issue here. Changing settings clears cache. Baking sucessfully caches a new simulation that shows none of the issues you report. Particulars: - I temporarily cleared the Dynamic Hair checkbox, which cleared the cache loaded with your file. - Then, probably unnecessarily, ran the animation with Dynamic Hair unchecked, just to satisfy myself that there were zero frames cached in memory. ## Finally, I restored the Dynamic Hair checkbox and baked all 100 frames. Blender reported a cache of 100 frames, consuming about 25.2 MB This gave me a clean animation. See **#68681.mkv** Compare with the animation made with your original file and its original cached data. See **T68681_original_cache.mkv** To make these animations, I modified your file slightly: I put a damped track constraint on the camera so that it would follow the head. There does seem to be something incorrect about the cached simulation in your posted file. The simulation is cut short to 68 frames, and the system here had trouble restarting the simulation at frame 69, given your original cached data (the hair explodes). At the end of the run, Blender reports inexact data from frame 0 - not a good sign. All that notwithstanding, fully clearing the cache and restarting the simulation from the first frame produced a complete and viable simulation - at least on my hardware. This suggests to me that there is some aspect of your system that is corrupting the caching of your simulation -- every time -- likely from the very first frame. In light of that, please also consider posting your system information. When in Blender, go to the help menu and choose "Save System Info" Post the resulting file here. Thank you! [system-info.txt](https://archive.blender.org/developer/F7666619/system-info.txt) (My system information, for reference) [#68681.mkv](https://archive.blender.org/developer/F7666622/T68681.mkv) #68681.mkv - animation from regenerated cache [T68681_original_cache.mkv](https://archive.blender.org/developer/F7666624/T68681_original_cache.mkv) T68681_original_cache.mkv - animation from original cached data.

Imre Varga commented

2019-08-16 06:12:30 +02:00

Thank you for your work so far,

First of all my system information:

190816_system-info_imrevarga.txt

I think I have narrowed the problem down somewhat. It seems to be related to flat / smooth shading. The following video shows my screen capture with and without hair dynamics as well as with smooth and flat shading.

190816_hair_dynamics_flat_smooth.flv

I have also attached a video where jiggle bones work in the viewport but not in the final render. Strangely, the jiggle is seen at the beginning of the movement, but then it stops. I know it's just an add-on but the problem might be related to the issue on hand.

190816_jiggle_bones_dont_render.flv

Thank you for your work so far, First of all my system information: [190816_system-info_imrevarga.txt](https://archive.blender.org/developer/F7666763/190816_system-info_imrevarga.txt) I think I have narrowed the problem down somewhat. It seems to be related to flat / smooth shading. The following video shows my screen capture with and without hair dynamics as well as with smooth and flat shading. [190816_hair_dynamics_flat_smooth.flv](https://archive.blender.org/developer/F7666768/190816_hair_dynamics_flat_smooth.flv) I have also attached a video where jiggle bones work in the viewport but not in the final render. Strangely, the jiggle is seen at the beginning of the movement, but then it stops. I know it's just an add-on but the problem might be related to the issue on hand. [190816_jiggle_bones_dont_render.flv](https://archive.blender.org/developer/F7666779/190816_jiggle_bones_dont_render.flv)

Garry R. Osgood commented

2019-08-16 13:35:56 +02:00

Hi Imre,
At first glance, I see nothing unusual in system-info_imrevarga.txt. I need to spend further time with it, but not right now - I'm off to my job and won't be home again until quite late tonight - 22:00 zulu or so.
It seems that when you set mesh smoothing to flat, the simulation runs properly. (Here, linux/amd card, smooth/flat is irrelevant. The simulation runs correctly in both settings).
That suggests a workaround: First, set mesh smoothing to flat, then bake the simulation - in the cache settings, Particle properties, click on the "Bake" button and let the bake run for the full length of the animation. This is similar to what @lichtwerk proposed (Delete cache, set smooth off, Bake, test animation in the timeline - new step in bold). I propose that this approach will at least give you a sane cache of the simulation to save and work with and you can move forward with your project. If it does, I'd appreciate a confirmation here. Thanks!

Hi Imre, At first glance, I see nothing unusual in system-info_imrevarga.txt. I need to spend further time with it, but not right now - I'm off to my job and won't be home again until quite late tonight - 22:00 zulu or so. It seems that when you set mesh smoothing to flat, the simulation runs properly. (Here, linux/amd card, smooth/flat is irrelevant. The simulation runs correctly in both settings). That suggests a workaround: First, set mesh smoothing to flat, then bake the simulation - in the cache settings, Particle properties, click on the "Bake" button and let the bake run for the full length of the animation. This is similar to what @lichtwerk proposed (Delete cache, **set smooth off,** Bake, test animation in the timeline - new step in bold). I propose that this approach will at least give you a sane cache of the simulation to save and work with and you can move forward with your project. If it does, I'd appreciate a confirmation here. Thanks!

Imre Varga commented

2019-08-16 13:57:42 +02:00

Ok, thanks so far, I will go on trying on Sunday since I am travelling right now ...

Imre Varga commented

2019-08-18 15:12:17 +02:00

Hi Garry,

So I have done some more research and found out the following:

without particle editing: flat works, smooth doesn't work, but can be used with baking in flat first as you suggested
with particle editing done with smooth shading on: flat doesn't work, smooth doesn't work
with particle editing done with flat shading on: flat works, smooth works as well and even renders ok

190818_hair_dynamics_particle_edit_flat_smooth.flv

The confusing part is that you have to do particle editing to get to work. All this behaviour is certainly not as intended and may still be considered a bug, but at least there is a safe workflow for me now:

do particle editing with flat shading on
make sure the subsurf modifier is below the particle system in the stack

The other big issue I have is the jiggle bones not rendering as I mentioned above. Should I open another case for that or can addons not be considered here?

Best regards

Imre

Hi Garry, So I have done some more research and found out the following: - without particle editing: flat works, smooth doesn't work, but can be used with baking in flat first as you suggested - with particle editing done with smooth shading on: flat doesn't work, smooth doesn't work - with particle editing done with flat shading on: flat works, smooth works as well and even renders ok [190818_hair_dynamics_particle_edit_flat_smooth.flv](https://archive.blender.org/developer/F7670744/190818_hair_dynamics_particle_edit_flat_smooth.flv) The confusing part is that you have to do particle editing to get to work. All this behaviour is certainly not as intended and may still be considered a bug, but at least there is a safe workflow for me now: - do particle editing with flat shading on - make sure the subsurf modifier is below the particle system in the stack The other big issue I have is the jiggle bones not rendering as I mentioned above. Should I open another case for that or can addons not be considered here? Best regards Imre

Garry R. Osgood commented

2019-08-20 15:03:10 +02:00

Thank you for the confirmation and the added information about edit mode effects. I think the object setting of flat/smooth shading is key - and that NVIDIA cards are in place. Those are the two salient aspects of this bug. People without an NVIDIA card cannot observe or confirm this bug.

Another bug report for jiggle bones? In general, one bug report per problem, so please do. It makes it difficult researching issues when two problems lurk under the heading of one. That way, key information is overlooked. One caution: Only report the jiggle bones add on bug here if that add-on is a part of the Blender distribution. I can't recall off-hand if jiggle bones is a Blender add-on or is authored by a third party. In the latter case, the third-party author should get the report, not the people here.

@lichtwerk : I think @imrevarga has answered your question: (Delete Bake, then Bake fix it for you?) Yes, when object -> shading ->is flat. When object -> shading -> is smooth the answer is no. In the latter case, blender also creates a corrupted cache (via baking or by playing through the timeline). That file, with the corrupted cache, can be uploaded, such as the first blend file in this thread, and other people can see the results of the bug, though, without an NVIDIA card, cannot recreate the bug. If your test machine does not have an NVIDIA card then the bug does not happen for you. Nor does it for me (with an AMD card). In light of this, please consider setting this report to "Triage by Developer."
@imrevarga: I suspect the request "Have you updated your drivers?" may be in the offing. You are at or around 425. It seems to me that NVIDIA published 431 at the end of July. I am not convinced that the driver is at root: the reporter of #68737 has a current 431.70 NVIDIA driver and also saw the issue with smooth, instead of flat shading object setting. But that is worth a shot if it solves the problem and is not an undue burden.

I will continue exploring how cloth modifier cache generation proceeds (which hair particles borrow for dynamics), and why a particular graphics card might matter. Take care.

Thank you for the confirmation and the added information about edit mode effects. I think the object setting of flat/smooth shading is key - and that NVIDIA cards are in place. Those are the two salient aspects of this bug. People without an NVIDIA card cannot observe or confirm this bug. **Another bug report for jiggle bones?** In general, one bug report per problem, so please do. It makes it difficult researching issues when two problems lurk under the heading of one. That way, key information is overlooked. One caution: Only report the jiggle bones add on bug here if that add-on is a part of the Blender distribution. I can't recall off-hand if jiggle bones is a Blender add-on or is authored by a third party. In the latter case, the third-party author should get the report, not the people here. @lichtwerk : I think @imrevarga has answered your question: (Delete Bake, then Bake fix it for you?) Yes, when object -> shading ->**is flat**. When object -> shading -> **is smooth** the answer is no. In the latter case, blender also creates a corrupted cache (via baking or by playing through the timeline). That file, with the corrupted cache, can be uploaded, such as the first blend file in this thread, and other people can see the results of the bug, though, without an NVIDIA card, cannot recreate the bug. If your test machine does not have an NVIDIA card then the bug does not happen for you. Nor does it for me (with an AMD card). In light of this, please consider setting this report to "Triage by Developer." @imrevarga: I suspect the request "Have you updated your drivers?" may be in the offing. You are at or around 425. It seems to me that NVIDIA published 431 at the end of July. I am not convinced that the driver is at root: the reporter of #68737 has a current 431.70 NVIDIA driver and also saw the issue with smooth, instead of flat shading object setting. But that is worth a shot if it solves the problem and is not an undue burden. I will continue exploring how cloth modifier cache generation proceeds (which hair particles borrow for dynamics), and why a particular graphics card might matter. Take care.

Philipp Oeser changed title from ~~hair dynamics simulation doesn't work~~ to Hair Dynamics: simulation doesn't work depending on smooth/flat shaded surfaces (and nvidia gpus?)

2019-09-04 15:31:45 +02:00

Philipp Oeser commented

2019-11-28 10:59:05 +01:00

Added subscriber: @MrJoMo

Richard Antalik commented

2020-01-07 21:26:01 +01:00

Added subscriber: @iss

Richard Antalik commented

2020-01-07 21:26:01 +01:00

Changed status from 'Needs Developer To Reproduce' to: 'Needs User Info'

Richard Antalik commented

2020-01-07 21:26:01 +01:00

I am not able to reproduce this (after clearing cache).

@imrevarga Is this still an issue with latest build, even if there is workaround? https://builder.blender.org/download/

I am not able to reproduce this (after clearing cache). @imrevarga Is this still an issue with latest build, even if there is workaround? https://builder.blender.org/download/

Joao Morgado commented

2020-01-11 22:49:21 +01:00

This issue is still happening for me. Attached is a screen recording of it using the latest 2.82 Beta Blender 2020-01-11 16-43-31.mp4

This issue is still happening for me. Attached is a screen recording of it using the latest 2.82 Beta [Blender 2020-01-11 16-43-31.mp4](https://archive.blender.org/developer/F8270524/Blender_2020-01-11_16-43-31.mp4)

Richard Antalik commented

2020-01-12 03:40:01 +01:00

Changed status from 'Needs User Info' to: 'Needs Developer To Reproduce'

Richard Antalik commented

2020-01-12 03:40:01 +01:00

Same OS, build from day earlier and still can not reproduce.

Seems like GPU issue.

Same OS, build from day earlier and still can not reproduce. Seems like GPU issue.

Joao Morgado commented

2020-01-17 03:22:22 +01:00

I just checked it again and there's some inconsistent behavior happening.

The problem is still happening, but if I change the default number of particles it appears to be fixed. Check video attached.Blender 2020-01-16 21-18-27.mp4

I just checked it again and there's some inconsistent behavior happening. The problem is still happening, but if I change the default number of particles it appears to be fixed. Check video attached.[Blender 2020-01-16 21-18-27.mp4](https://archive.blender.org/developer/F8282426/Blender_2020-01-16_21-18-27.mp4)

Jacques Lucke commented

2020-02-12 15:19:34 +01:00

Added subscriber: @JacquesLucke

Jacques Lucke commented

2020-02-12 15:19:34 +01:00

I'm also not able to reproduce the issue yet. It looks as if there is simply some missing update for you.

2020-02-12 15-18-46.mp4

I'm also not able to reproduce the issue yet. It looks as if there is simply some missing update for you. [2020-02-12 15-18-46.mp4](https://archive.blender.org/developer/F8336428/2020-02-12_15-18-46.mp4)

Joselu commented

2020-02-13 10:49:38 +01:00

In my case the problem was solved a couple of nvidia driver updates ago. Sorry to answer so late.
I was in contact with nvidia to help you find a solution.

In my case the problem was solved a couple of nvidia driver updates ago. Sorry to answer so late. I was in contact with nvidia to help you find a solution.

Richard Antalik commented

2020-02-13 14:35:06 +01:00

Changed status from 'Needs Developer To Reproduce' to: 'Resolved'

Richard Antalik closed this issue

2020-02-13 14:35:06 +01:00

Richard Antalik self-assigned this 2020-02-13 14:35:06 +01:00

Richard Antalik commented

2020-02-13 14:35:06 +01:00

Thanks for update.

Joao Morgado commented

2020-02-13 15:07:28 +01:00

In #68681#870889, @Xeluaxeman wrote:
In my case the problem was solved a couple of nvidia driver updates ago. Sorry to answer so late.
I was in contact with nvidia to help you find a solution.

I'm running the latest nvidia studio driver on a 2070 Super and I still see it. I will test again tonight on the latest 2.83 build, to see if there's any improvement.

> In #68681#870889, @Xeluaxeman wrote: > In my case the problem was solved a couple of nvidia driver updates ago. Sorry to answer so late. > I was in contact with nvidia to help you find a solution. I'm running the latest nvidia studio driver on a 2070 Super and I still see it. I will test again tonight on the latest 2.83 build, to see if there's any improvement.

Mugur Marculescu commented

2020-03-30 07:28:57 +02:00

Added subscriber: @mugurm

Mugur Marculescu commented

2020-03-30 07:28:57 +02:00

I am on Mac OS 10.15.4 using Blender v2.82a using an eGPU AMD Vega 56 and unfortunately am experiencing this issue. Smooth shading results in no simulation, change to Shade Flat, works. Should I file a new bug or does this need to be reopened?

Philipp Oeser commented

2020-03-30 07:43:02 +02:00

Changed status from 'Resolved' to: 'Needs Developer To Reproduce'

Philipp Oeser reopened this issue

2020-03-30 07:43:02 +02:00

Richard Antalik was unassigned by Philipp Oeser

2020-03-30 07:43:31 +02:00

MrP commented

2020-04-23 05:31:04 +02:00

Added subscriber: @thechode

Philipp Oeser commented

2020-05-12 15:52:10 +02:00

Added subscriber: @craigievar

Clément Foucault commented

2020-06-25 15:46:00 +02:00

Added subscriber: @fclem

Clément Foucault commented

2020-06-25 15:46:00 +02:00

I can't believe it's a GPU issue as the actual simulation is broken (it is saved and we can see the issue when opening baked files). So to me, it's a baking / simulation issue only.

Can someone who has still the bug reposts a file containing a broken animation (just to corroborate my hypothesis)?

I can't believe it's a GPU issue as the actual simulation is broken (it is saved and we can see the issue when opening baked files). So to me, it's a baking / simulation issue only. Can someone who has still the bug reposts a file containing a broken animation (just to corroborate my hypothesis)?

Joao Morgado commented

2020-06-25 15:51:39 +02:00

In #68681#965385, @fclem wrote:
I can't believe it's a GPU issue as the actual simulation is broken (it is saved and we can see the issue when opening baked files). So to me, it's a baking / simulation issue only.

Can someone who has still the bug reposts a file containing a broken animation (just to corroborate my hypothesis)?

I’m not at my computer right now. But I’ll prep a file for you later and post it here

> In #68681#965385, @fclem wrote: > I can't believe it's a GPU issue as the actual simulation is broken (it is saved and we can see the issue when opening baked files). So to me, it's a baking / simulation issue only. > > Can someone who has still the bug reposts a file containing a broken animation (just to corroborate my hypothesis)? I’m not at my computer right now. But I’ll prep a file for you later and post it here

Joao Morgado commented

2020-06-26 00:31:21 +02:00

In #68681#965385, @fclem wrote:
I can't believe it's a GPU issue as the actual simulation is broken (it is saved and we can see the issue when opening baked files). So to me, it's a baking / simulation issue only.

Can someone who has still the bug reposts a file containing a broken animation (just to corroborate my hypothesis)?

Hey @fclem. Here's a demo file, my system's info and a video detailing what happens. Below is a description of steps to reproduce the error:

Start Blender
Add hair system to default cube
Turn on hair dynamics
Animate cube's location
Play the animation
At this point everything works as expected
Turn on Shade Smooth on the cube
Play the animation again
At this point the error should be visible. Cube moves and and hair origins follow, but dynamics on the rest of the hair don't work
Change the emission number on the particle options by 1 (any number should work)
Play the animation again
This appears to fix the problem

Hair Problem Demo.blend
Blender 2020-06-25 18-18-28.mp4
system-info.txt

Hope this helps. Let me know if I can help with anything else.

> In #68681#965385, @fclem wrote: > I can't believe it's a GPU issue as the actual simulation is broken (it is saved and we can see the issue when opening baked files). So to me, it's a baking / simulation issue only. > > Can someone who has still the bug reposts a file containing a broken animation (just to corroborate my hypothesis)? Hey @fclem. Here's a demo file, my system's info and a video detailing what happens. Below is a description of steps to reproduce the error: - Start Blender - Add hair system to default cube - Turn on hair dynamics - Animate cube's location - Play the animation - **At this point everything works as expected** - Turn on Shade Smooth on the cube - Play the animation again - **At this point the error should be visible. Cube moves and and hair origins follow, but dynamics on the rest of the hair don't work** - Change the emission number on the particle options by 1 (any number should work) - Play the animation again - **This appears to fix the problem** [Hair Problem Demo.blend](https://archive.blender.org/developer/F8644631/Hair_Problem_Demo.blend) [Blender 2020-06-25 18-18-28.mp4](https://archive.blender.org/developer/F8644636/Blender_2020-06-25_18-18-28.mp4) [system-info.txt](https://archive.blender.org/developer/F8644646/system-info.txt) Hope this helps. Let me know if I can help with anything else.

Richard Antalik commented

2020-11-25 16:33:19 +01:00

@MrJoMo I am going over old reports. Can you still reproduce tis issue in latest build form https://builder.blender.org/download/?

Joao Morgado commented

2020-11-25 16:58:05 +01:00

In #68681#1061153, @iss wrote:
@MrJoMo I am going over old reports. Can you still reproduce tis issue in latest build form https://builder.blender.org/download/?

Hey Richard,

Thanks for checking inn on this.

I just tested with the latest 2.91 Beta and 2.92 Alpha and it appears to be fixed.
I'm not at my main workstation though, I can run the tests back again in main workstation in a couple of days when I get back home since that's where I noticed the problem initially.

If it helps the computer I'm on now has the following specs.

Asus Zephyrus G14
AMD Ryzen 9 4900HS
16GB DDR4 SDRAM @ 3200Mhz
NVIDIA GeForce RTX 2060 Max-Q with 6GB GDDR6

> In #68681#1061153, @iss wrote: > @MrJoMo I am going over old reports. Can you still reproduce tis issue in latest build form https://builder.blender.org/download/? Hey Richard, Thanks for checking inn on this. I just tested with the latest 2.91 Beta and 2.92 Alpha and it appears to be fixed. I'm not at my main workstation though, I can run the tests back again in main workstation in a couple of days when I get back home since that's where I noticed the problem initially. If it helps the computer I'm on now has the following specs. Asus Zephyrus G14 AMD Ryzen 9 4900HS 16GB DDR4 SDRAM @ 3200Mhz NVIDIA GeForce RTX 2060 Max-Q with 6GB GDDR6

Richard Antalik commented

2020-11-25 17:23:27 +01:00

Thank you for re-checking. It would be best if you can test on machine that you was able to reproduce the issue originally. Or check if you can reproduce with older Blender version https://download.blender.org/release/ and latest version. This is just to be sure.

Hopefully this can be closed as resolved.

Thank you for re-checking. It would be best if you can test on machine that you was able to reproduce the issue originally. Or check if you can reproduce with older Blender version https://download.blender.org/release/ and latest version. This is just to be sure. Hopefully this can be closed as resolved.

Joao Morgado commented

2020-11-25 17:59:32 +01:00

In #68681#1061199, @iss wrote:
Thank you for re-checking. It would be best if you can test on machine that you was able to reproduce the issue originally. Or check if you can reproduce with older Blender version https://download.blender.org/release/ and latest version. This is just to be sure.

Hopefully this can be closed as resolved.

That's a good point Richard. I just downloaded 2.82 and tested on this machine and it was fine. So it may by something specific with my other setup.
I'll test it when I get back, but it's only going to be next week.

> In #68681#1061199, @iss wrote: > Thank you for re-checking. It would be best if you can test on machine that you was able to reproduce the issue originally. Or check if you can reproduce with older Blender version https://download.blender.org/release/ and latest version. This is just to be sure. > > Hopefully this can be closed as resolved. That's a good point Richard. I just downloaded 2.82 and tested on this machine and it was fine. So it may by something specific with my other setup. I'll test it when I get back, but it's only going to be next week.

Tom Grod commented

2020-11-30 19:02:12 +01:00

Added subscriber: @SmartySmart702

Tom Grod commented

2020-11-30 19:02:12 +01:00

Ok so I just found this Thread because I have the same problem.
Hair-Dynamics are not working if shade smooth is enabled.

Blender 2.91.0, Blender 2.83.9, Blender 2.82a and Blender 2.80
GTX 1070 (Driver Version: 457.30)
AMD Ryzen 5 2600
Win 10 Pro x64

It is working in the latest, nightly build version of Blender 2.79

Ok so I just found this Thread because I have the same problem. Hair-Dynamics are not working if shade smooth is enabled. Blender 2.91.0, Blender 2.83.9, Blender 2.82a and Blender 2.80 GTX 1070 (Driver Version: 457.30) AMD Ryzen 5 2600 Win 10 Pro x64 It is working in the latest, nightly build version of Blender 2.79

Philipp Oeser commented

2021-01-04 09:17:05 +01:00

Added subscriber: @frokes

chris legasse commented

2022-01-26 08:30:06 +01:00

Added subscriber: @Shoggoth.Smythers

chris legasse commented

2022-01-26 08:30:06 +01:00

I am having this same problem in blender 3.0

I am updating my drivers to see if that fixes it. Windows 10 64bit, GTX 1070

EDIT: New drivers did not fix the issue.

I am having this same problem in blender 3.0 ![image.png](https://archive.blender.org/developer/F12824716/image.png) I am updating my drivers to see if that fixes it. Windows 10 64bit, GTX 1070 EDIT: New drivers did not fix the issue.

Philipp Oeser removed the

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Hair Dynamics: simulation doesn't work depending on smooth/flat shaded surfaces (and nvidia gpus?) #68681

Finally, I restored the Dynamic Hair checkbox and baked all 100 frames. Blender reported a cache of 100 frames, consuming about 25.2 MB