Hi all, I haven't emailed on this email list before, but I'm happy to see discussion about the cloth simulator in Blender. It is the main reason why I started using Blender, and I know a fair amount of folks in my community (AI and robotics researchers) who would love to explore cloth capabilities.
I have used (Py)Bullet recently, and have collaborated with the folks working on cloth simulation as part of my Google internship. While they are working on it (see https://github.com/bulletphysics/bullet3/pull/2872) from my experience, for more physically realistic cloth, I honestly go with Blender. The main reason why I have used (Py)Bullet has less to do with the simulator quality and more to do with issues I ran into with vertex pinning / unpinning in Blender. For reference, I am the person who wrote this: https://devtalk.blender.org/t/pinning-and-moving-vertices-of-cloth-at-arbitrary-frame-sequences-with-updated-physics/13542 Daniel On Tue, Oct 20, 2020 at 8:24 AM darkdefende--- via Bf-committers < [email protected]> wrote: > I see that my name isn't with my email address. > So just so clarify, I'm Sebastian Parborg. > > On Tue, Oct 20, 2020 at 02:20:46PM +0200, [email protected] wrote: > > To fix the cloth tunneling though the cube, activate "Single sided" in > > the cube's collision settings and it should work much better. > > > > Anyways, during my recent work with Bullet, I tested some things that > > are currently not integrated into blender. > > > > Mainly Bullet softbodies and cloth. > > > > Both have their use cases, but as Brecht pointed out, the Bullet cloth > > physics is way more unstable and doesn't have no where near as many > > features as our current cloth sim. So outright replacing our current > > system with that would just be a downgrade on so many levels (except > > speed). > > > > I would say that all of our physics simulations currently needs a lot of > > work to be faster, more stable, and nicer to use. The majority of them > > feels half baked at the moment I my opinion. (And it shows as it seems a > > lot of people does not use them in production because they are simply not > > good enough yet) > > > > My current plan was to first make Bullet integration in Blender better. > > As I deem this to be the easier task. However I have a lot of other work > > I need to do, so progress is slow. > > This is also because I want the Bullet refactor to align nicely with our > > new node system. (So we don't have to do an other refactor for that) > > > > As Sergej pointed out, Mano Wii and I has been in talks on making the > > collision system better for cloth and also make it have move options so > > they user can make trade-offs if they want to. > > > > If you have any specific fixes or changes in mind. We would love to hear > > them. > > > > Welcome back. > > > > On Tue, Oct 20, 2020 at 01:39:01PM +0200, Sergej Reich via Bf-committers > wrote: > > > Bullet's cloth system is no replacement for what Blender currently has > and > > > I'm not aware of any available library that we could use without > having to > > > do a lot of modifications to make it work. > > > > > > Am Di., 20. Okt. 2020 um 12:26 Uhr schrieb Brecht Van Lommel via > > > Bf-committers <[email protected]>: > > > > > > > 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. > > > > https://www.youtube.com/watch?v=jU6-cI-z8HA > > > > > > > > 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: > > > > https://developer.blender.org/D8577 > > > > > > > > On Tue, Oct 20, 2020 at 11:52 AM Ton Roosendaal via Bf-committers < > > > > [email protected]> 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 - [email protected] - 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 > > > > > > _______________________________________________ > > > > > > Bf-committers mailing list > > > > > > [email protected] > > > > > > https://lists.blender.org/mailman/listinfo/bf-committers > > > > > _______________________________________________ > > > > > Bf-committers mailing list > > > > > [email protected] > > > > > https://lists.blender.org/mailman/listinfo/bf-committers > > > > > > > > > _______________________________________________ > > > > Bf-committers mailing list > > > > [email protected] > > > > https://lists.blender.org/mailman/listinfo/bf-committers > > > > > > > _______________________________________________ > > > Bf-committers mailing list > > > [email protected] > > > https://lists.blender.org/mailman/listinfo/bf-committers > _______________________________________________ > Bf-committers mailing list > [email protected] > https://lists.blender.org/mailman/listinfo/bf-committers > _______________________________________________ Bf-committers mailing list [email protected] https://lists.blender.org/mailman/listinfo/bf-committers
