Hair Particle Simulation Crashes Blender #44736

New Issue

Stephen Pflanze · 2015-05-17T01:23:58+02:00

Stephen Pflanze commented

2015-05-17 01:23:58 +02:00

System information:
OS Name Microsoft Windows 7 Ultimate
Version 6.1.7601 Service Pack 1 Build 7601
OS Manufacturer Microsoft Corporation
System Manufacturer Dell Inc.
System Model Precision #5600
System Type x64-based PC
Processor Intel(R) Xeon(R) CPU E5-2603 0 @ 1.80GHz, 1800 Mhz, 4 Core(s), 4 Logical Processor(s)
Processor Intel(R) Xeon(R) CPU E5-2603 0 @ 1.80GHz, 1800 Mhz, 4 Core(s), 4 Logical Processor(s)
Installed Physical Memory (RAM) 8.00 GB
Total Physical Memory 7.93 GB
Available Physical Memory 3.80 GB
Total Virtual Memory 15.9 GB
Video Card NVIDIA Quadro 600

Blender Version
Broken: 2.74
Worked: 2.73

Hair simulation causes the Blender application to close and disappear from the screen.

Exact steps for others to reproduce the error
Download the file from:
http://www.pasteall.org/blend/35992
and run a simulation.

I am reporting this as a bug because no one in this thread:
http://blenderartists.org/forum/showthread.php?370582-Hair-Simulation-Crashes-Blender&p=2866807#post2866807
was able to solve it in 2.74. In this thread Photox said it worked in 2.73 stable.

System information: OS Name Microsoft Windows 7 Ultimate Version 6.1.7601 Service Pack 1 Build 7601 OS Manufacturer Microsoft Corporation System Manufacturer Dell Inc. System Model Precision #5600 System Type x64-based PC Processor Intel(R) Xeon(R) CPU E5-2603 0 @ 1.80GHz, 1800 Mhz, 4 Core(s), 4 Logical Processor(s) Processor Intel(R) Xeon(R) CPU E5-2603 0 @ 1.80GHz, 1800 Mhz, 4 Core(s), 4 Logical Processor(s) Installed Physical Memory (RAM) 8.00 GB Total Physical Memory 7.93 GB Available Physical Memory 3.80 GB Total Virtual Memory 15.9 GB Video Card NVIDIA Quadro 600 **Blender Version** Broken: 2.74 Worked: 2.73 Hair simulation causes the Blender application to close and disappear from the screen. **Exact steps for others to reproduce the error** Download the file from: http://www.pasteall.org/blend/35992 and run a simulation. I am reporting this as a bug because no one in this thread: http://blenderartists.org/forum/showthread.php?370582-Hair-Simulation-Crashes-Blender&p=2866807#post2866807 was able to solve it in 2.74. In this thread Photox said it worked in 2.73 stable.

Stephen Pflanze commented

2015-05-17 01:23:58 +02:00

Changed status to: 'Open'

Stephen Pflanze commented

2015-05-17 01:23:58 +02:00

Added subscriber: @megasoid

Bastien Montagne commented

2015-05-17 15:54:53 +02:00

Added subscriber: @mont29

Bastien Montagne commented

2015-05-17 15:54:53 +02:00

Man, that simulation takes more than ages to run! We can't use that for investigation.

Tried to replicate with much simpler case (mere cube with ten hairs), no crash here. Can you please try to attach here a much simpler/lighter case that crashes for you?

PS: Getting segfault when closing Blender (to interrupt the never-ending simulation), which seem to be caused by shared data between particles, cloth modifier, and possibly others, like effector_weights, but think this is due to interruption during work…

Man, that simulation takes more than ages to run! We can't use that for investigation. Tried to replicate with much simpler case (mere cube with ten hairs), no crash here. Can you please try to attach here a much simpler/lighter case that crashes for you? PS: Getting segfault when closing Blender (to interrupt the never-ending simulation), which seem to be caused by shared data between particles, cloth modifier, and possibly others, like effector_weights, but think this is due to interruption during work…

Brecht Van Lommel commented

2015-05-17 16:21:50 +02:00

Added subscriber: @brecht

Brecht Van Lommel commented

2015-05-17 16:21:50 +02:00

Maybe the crash and the simulation running so slowly are both caused by the same problem? For me Blender froze a long time, I didn't wait to see if it would crash. I noticed that BLI_bvhtree_overlap is returning 100 million collision pairs, which seems excessive.

Maybe the crash and the simulation running so slowly are both caused by the same problem? For me Blender froze a long time, I didn't wait to see if it would crash. I noticed that `BLI_bvhtree_overlap` is returning 100 million collision pairs, which seems excessive.

Stephen Pflanze commented

2015-05-17 16:45:20 +02:00

It crashes and closes on me immediately after simulation start. Maybe it does not crash on your computer because maybe yours has more resources than mine.

It has crashed for Photox, in 2.74 and not 2.73. If the crash on mine and Photox's is due to the same problem that causes it to run slowly on yours, maybe it will run much faster on yours in version 2.73.

If I change the model to run faster on yours, it is likely the problem will not manifest itself.

It crashes and closes on me immediately after simulation start. Maybe it does not crash on your computer because maybe yours has more resources than mine. It has crashed for Photox, in 2.74 and not 2.73. If the crash on mine and Photox's is due to the same problem that causes it to run slowly on yours, maybe it will run much faster on yours in version 2.73. If I change the model to run faster on yours, it is likely the problem will not manifest itself.

Lukas Tönne was assigned by Bastien Montagne

2015-05-25 15:22:21 +02:00

Bastien Montagne commented

2015-05-25 15:22:21 +02:00

Assigning to Lukas, indeed overlap seems to be an issue, which could explain huge memory usage and slow simulation...

Lukas Tönne commented

2015-05-25 17:37:28 +02:00

Closed as duplicate of #42577

Lukas Tönne closed this issue

2015-05-25 17:37:28 +02:00

Lukas Tönne commented

2015-05-25 17:44:38 +02:00

This is a known issue: #42577

The problem is in the way contact points are generated for cloth and hair. It uses a nearest-point search on BVH trees. This method is usually quite fast, but it's nowhere close to actual physical contact point generation (to get an impression of the complexity of the problem, see https:bullet.googlecode.com/files/GDC10_Coumans_Erwin_Contact.pdf). What's making the process so terribly slow here is the "epsilon" distance used to give collision objects some offset. If this epsilon becomes larger than the smallest scale of BVH grid cells the algorithm generates ahuge// amount of potential contact pairs. Only way to avoid this is to reduce the Outer and Inner margins of the collider object - they are set 1.0 in the file, meaning almost all mesh faces will be considered for collision for all the hair points.

There is no way to fix it with the current system, we will need a proper contact point generation method.

This is a known issue: #42577 The problem is in the way contact points are generated for cloth and hair. It uses a nearest-point search on BVH trees. This method is usually quite fast, but it's nowhere close to actual physical contact point generation (to get an impression of the complexity of the problem, see https:*bullet.googlecode.com/files/GDC10_Coumans_Erwin_Contact.pdf). What's making the process so terribly slow here is the "epsilon" distance used to give collision objects some offset. If this epsilon becomes larger than the smallest scale of BVH grid cells the algorithm generates a*huge// amount of potential contact pairs. Only way to avoid this is to reduce the `Outer` and `Inner` margins of the collider object - they are set 1.0 in the file, meaning almost all mesh faces will be considered for collision for all the hair points. There is no way to fix it with the current system, we will need a proper contact point generation method.

Mylo Pinto Rizvi commented

2020-04-17 15:15:44 +02:00

Added subscriber: @Low_Polygon42

Mylo Pinto Rizvi commented

2020-04-17 15:15:44 +02:00

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Mylo Pinto Rizvi commented

2020-04-17 15:17:42 +02:00

This comment was removed by @Low_Polygon42

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Mylo Pinto Rizvi commented

2020-04-17 15:19:15 +02:00

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Hair Particle Simulation Crashes Blender #44736