Slow Cloth Simulation in 2.74

Hello.
I created this typical flag with wind as example:
http://www.pasteall.org/blend/35054

I have subdivide much the flag because the problem is more evident with many vertices.
When I press play animation the first time the simulation is built very well at 24 fps in Blender 2.72 and 2.73a. But runs slow at 12 fps in 2.74 RC1. “Bake” is also slower in 2.74.
Do you also notice this drop in performance in 2.74?

Edit:
sorry, I had uploaded the wrong file. Now it is the correct

I haven’t run a cloth simulation, but my tests using 2.74 (including those found in graphicall.org) and the BMW benchmark, are slower than 2.73a.

Around 20 seconds, which is fairly significant. This was mirrored in GPU and GPU modes. Since 2.74 is a test build, there maybe a lot of further optimisation.

Even self collision looks different on 2.72/2.73a compared to 2.74 RC1 using the same .blend file to compare. The simulation looks worse in 2.74

http://www.pasteall.org/blend/35062

Hello rvectors, you’re new in the forum and I had not seen your message that was published with delay.

Yes, it is test build, but RC. This should be “almost” cooked :slight_smile:
The low speed is worrisome. But even more worrying is that the results are different between different versions with the same projetc/file. For example, cloth and self collision in 2.74 seem not to be working properly.

I just tested your .blend file is just running fine apart from the cloth is going through the mesh. fps 24 after the cache.

Thank for the testing erickBlender.

Yes, after the cache the animation runs at 24fps. I meant the first time you play the animation and the cache is built. Or the time it takes to Bake the cloth animation.

In the second blend file I uploaded, ¿Self collision looks similar in 2.72/2.73a compared to 2.74?

I’m using Kubuntu Linux 64bits.

Edit:
You note that you must compare 2.74 with version 2.72 or 2.73a. In version 2.73 does not work cloth collision because a bug.

Hi YAFU, post bug report about slow fps in RC2.

https://developer.blender.org/T44031

Cheers, mib

Thanks mib2berlin! But, Have you been able to reproduce the problem?
I don’t want any developer get upset, like this:
http://www.blenderartists.org/forum/showthread.php?364234-Copy-paste-Nodes-from-one-project-to-another-with-Ctrl-C-and-Ctrl-V

Edit:
I guess I made a silly question, since the report shows your hardware and your own tests

EDIT:

Woops. I wasn’t running 2.73a like I thought. I ran a more comprehensive test with self-collision quality 5, plus did a visual check for quality.

2.72b - 1:07.73
2.73a - 1:06
2.74 RC2 - 1:32.59

I do see significant differences between versions. It appears the sim in 2.74 RC2 is much stiffer, although I did not change any settings except for self-collision quality. 2.72b and 2.73a are similar enough to not be worried about it, but 2.74 is certainly the big change.

Here are some playblasts from each version:



You’ll notice in 2.72b and 2.73a that the farthest the cloth falls is at frame 61 or 62. 2.74RC2’s furthest is roughly frame 35 and not nearly as extreme as the others.

rvectors I’m taking exactly the same hit you are and I’m in 2.74 rc2. Twenty seconds on a 7 minute frame which hasn’t been baked yet. And, yeah when animating 20 seconds is significant. I’m still excited about the image as plane - movie feature but will wait for hopefully a faster version for rendering.

What about the quality of the simulation?

Here I share two videos made with 2.73a and 2.74RC1. In 2.74 cloth self collision and collision seem not working well, small rebound in self collison and the mesh ends up falling down. Tested with the second blend file I uploaded in message #3

@Italic_, seems that you have noticed these differences in your tests, right?

Edit:
I’ve been thinking. Perhaps the problem regarding the quality of simulation in the second blend file is all related to Cloth and collision, not cloth self collision.
So, it could be related to the same 2.73 cloth and collision bug, or it is a different bug?

Quick update

Using 2.74 RC2 in comparison to RC1 - BMW benchmak is almost the same as 2.73a, couple of seconds more.

I ran your blend file and on first cache still confirm between 5-7fps worse in 2.74 RC2 vs 2.73a,

Probelm is, this might not be a factor of less optimised code, but maybe the cloth simulation is doing more, i.e has been improved in some way for a better overall simulation which requires changes to setup.

Although… the collision behaviour is also much different between the two blenders.

This problem is still present in 2.75 test build. 2.73a simulation is twice faster than 2.75. The problem that the simulation result is different in these versions on the same project also persists.
https://developer.blender.org/T44031
https://developer.blender.org/T44157
https://developer.blender.org/T43911

Ah, I thought I was going crazy. I was trying to run a cloth sim just today and wondered why it was taking much longer than I remembered. 2.75 for me. Anyone know why this is happening in simple terms?

I’m sorry, I don’t know. Only what it is explained in these reports.

Here´s hoping this patch also solves the slowness issue, as it seems to close three other bugs in one go :slight_smile:

Hi BrilliantApe.
I tried the patch. “untitledD.blend” from this report:
https://developer.blender.org/T43911
and the simulation seems to perform similarly in 2.73a and the patched version.

But the patch does not solve the two problems I have mentioned here (.blend shared in message #1 and #3)

  • flag3.blend
    2.73a --> 25 fps (27 fps if I change fps settings from render tab)
    Patched 2.75 --> 13 fps

  • flag3_collision.blend
    The simulation result is still different between 2.73a and patched 2.75 from master

see this settings with Blender 2.75a
[ATTACH=CONFIG]397085[/ATTACH]
It’s ok for you ?

mythcat
You can download Blender 2.73a from here (2.73a, not 2.73):
https://download.blender.org/release/Blender2.73/
And you compare with 2.75 but the development version downloaded from BuildBot:
https://builder.blender.org/download/

If you are using Windows, the .zip version is portable (you don’t need install it)
Please, you share the .blend file to be sure that we are using exactly the same settings.

Another thing that is not related to cloth in blender. I saw that in your model exported from Makehuman the transformations were blocked, so I guess you were using “mhx” extension. Some people recommend “mhx2”. I don’t remember why this plugin is not an official Makehuman plugin (I think it was because some license, but I don’t remember well). So look at google for “mhx2”, download and install.

@YAFU thank’s ! I will search mhx2 plugin.