rayt Posted November 16, 2017 Share Posted November 16, 2017 Hi Odforcers, Im working on a project where I have to tear up a lawn using bullet rbd's and hair to generate grass. Ive come into a problem, or maybe a bug where the grass in the deforming rbd patches becomes very long either when moving through space, or even at rest. I cant seem to find any other topic where this has happened before. Has anybody encountered this kind of problem with H16's hair and deform groom? Any incite would be appreciated. Id love to attach a screen shot however the content is under NDA. All I can say is imagine a bunch of curves spidering out from underneath a few selected skin patches. Cheers! Quote Link to comment Share on other sites More sharing options...
Guest tar Posted November 17, 2017 Share Posted November 17, 2017 yeah - like the attached? Check your mass and physical settings, also add a substep, Quote Link to comment Share on other sites More sharing options...
rayt Posted November 17, 2017 Author Share Posted November 17, 2017 (edited) Thats pretty much what is happening. I am unsure where mass and substeps are. Ive been having to build the setup from scratch aat times and I dont seem to see a mass or substep attribute. EDIT: A colleague also noted that we are using a deform not a simulate hair so mass and substeps are not available. Edited November 17, 2017 by rayt Quote Link to comment Share on other sites More sharing options...
Guest tar Posted November 17, 2017 Share Posted November 17, 2017 (edited) haven't seen that happen and it shouldn't happen as GuideDeform is simply using an attribute interpolate I think. Check the attached. GroomedOnly.hiplc Edited November 17, 2017 by tar Quote Link to comment Share on other sites More sharing options...
rayt Posted November 17, 2017 Author Share Posted November 17, 2017 Turns out that the issue is the collision object used to press the hair system down. Removing it fixes the odd stringy grass shapes but doesnt negate the fact that the collider is needed. Im just not sure what needs to be done. It seems that the collider in question only affects one point on each of the guides and usually sets the single point to a 90 degree angle which then messes up the groom. Quote Link to comment Share on other sites More sharing options...
Guest tar Posted November 17, 2017 Share Posted November 17, 2017 Trying to understand the setup, are you using 'guide collide with vdbSOP'? Quote Link to comment Share on other sites More sharing options...
rayt Posted November 17, 2017 Author Share Posted November 17, 2017 Yes, im using a guild collision sop with a vdb of a walk cycle. Quote Link to comment Share on other sites More sharing options...
Guest tar Posted November 17, 2017 Share Posted November 17, 2017 hmm - that's not happening here. so not sure. WalkingGrass.hiplc Quote Link to comment Share on other sites More sharing options...
rayt Posted November 23, 2017 Author Share Posted November 23, 2017 Been a week with no real success. Ive had to go over everything with a fine comb and im at a point of rebuilding a sim from scratch. Using just an rbd cube and the shelf tools I have build a simming object that works well and is fairly quick. My real question at this point is, when using a custom groom guide with multiple rbd objects, do you need a deform in your network to prevent jitters or breaking sims? Quote Link to comment Share on other sites More sharing options...
Guest tar Posted November 23, 2017 Share Posted November 23, 2017 I'm not following how you've set this up. A deform would be needed to lock the curves onto a RBD simulation, then the wire sim adds the dynamics to the hairs. Quote Link to comment Share on other sites More sharing options...
Deviner Posted November 23, 2017 Share Posted November 23, 2017 Hey Ray, I had the same problem actually. I had wire simulation and collision with vdb. Didn't solve it really, but if you'll try to use 'ray intersect' as a collision method increase substeps check scene scale and all parameters. it could work Quote Link to comment Share on other sites More sharing options...
rayt Posted November 23, 2017 Author Share Posted November 23, 2017 (edited) It looks like Marty's setup was the key to the problem. The GroomOnly.hiplc clued me into that to have the sim behave properly is to set up an animated mesh normally with a groom deform. Then apply the sim. Asside from the occasional jump in hair length on certain areas, which im pretty sure is a substep thing, the jitter is gone. From my understanding the sim drives the deform which then drives the groom. EDIT: if you know of a way to prevent random long groom curves I would love to hear it. Everything works well save a patch that all of a sudden becomes very long for one frame then reverts back to normal. Edited November 23, 2017 by rayt Quote Link to comment Share on other sites More sharing options...
Tomasz Dabert Posted January 30, 2018 Share Posted January 30, 2018 I had the same problem, increase or decrease spatial scale, it helped me a ton! Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.