[Bf-committers] It's time to get rid of cloth

Brecht Van Lommel brechtvanlommel at gmail.com
Tue Oct 20 12:26:19 CEST 2020

The most important thing for cloth is that you can get it to give good
results in real world cases, and the cloth simulation changes were based on
work done for Agent 327.

In practice you use smaller time steps and the fast-moving cube will get
collided with anyway.

Continuous collision detection is great for handling fast-moving objects,
but arguably handling cloth that is nearly at rest and continuously
colliding with the character is a much harder problem. Most cloth
simulation demo videos stop while everything is still in motion, but what
happens after is just as important.

Anyway, there's definitely much room for improvement here, but it should be
tested on real-world cases. For example from what I've seen, Bullet cloth
is more reliable at high frame rates, but does not produce good results or
wrinkling details when turning up the quality. I've not yet seen an
open-source cloth library that we could just plug in and get much better
results, but it would be great if there was one.

Some work on cloth collision is being done here:

On Tue, Oct 20, 2020 at 11:52 AM Ton Roosendaal via Bf-committers <
bf-committers at blender.org> wrote:

> Hi Joe,
> This is a bit harsh, there have been good cloth contributions to Blender
> by Luca Rood. The current module owner for it is Sebastian Parborg though.
> I'd suggest to connect with them to see what steps forward could be.
> We are also in the process of making a good node physics system to allow
> solvers like this in a more generic setting. Design for this is ongoing.
> It's super cool to see you want to come back, just give it a bit of time
> to figure out who's doing what now.
> Als note that we (including Blender Foundation / Institute) are in the
> process of organizing ourselves much better, including onboarding, best
> practices, engineering standards amd strict requirements for a good
> design process - including the docs.
> We lack in a lot of areas, and the consensus is to especially put
> efforts in bringing the current state of the code in control (functional
> and technical specs), before recoding modules entirely.
> -Ton-
> ----------------------------------------------------------------------
> Ton Roosendaal - ton at blender.org - www.blender.org
> Chairman Blender Foundation, Director Blender Institute
> Buikslotermeerplein 161, 1025 ET Amsterdam, the Netherlands
> On 20/10/2020 00:30, Joe Eagar via Bf-committers wrote:
> > So, ten years ago I wrote several continuous collision detection systems
> > for cloth/hair, one of which I tried to push into trunk:
> >
> > https://www.youtube.com/watch?v=QBM3TBKO9w8
> >
> > And, here's how the cloth sim performs today:
> >
> > https://www.youtube.com/watch?v=5462m9yEkU8&feature=youtu.be
> >
> > If the cloth development process is this dysfunctional (this patch
> actually
> > passed review?
> > https://developer.blender.org/rB0666ece2e2f96571200d693d9d7bee1ca72d026f
> )
> > then I propose we eliminate the cloth code entirely and go with a third
> > party lib (Bullet?).
> >
> > Joe
> > _______________________________________________
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