nHair collisions

[mikael persson]

while I'm at it. What gods should one be sacrificing to to get collisions at all times while using nHair? I haven't discerned a pattern yet, but it's really hard to get my nHairs to collide with meshes that I've told to be passive colliders. At first I thought it was a 2017 issue when 2018 seemed to be behaving. But that didn't take long for 2018 to start acting up too.

I've checked all the obvious places. But might be missing something.. Is this a know issue?

Mikael

[desig...@gmail.com]

Did you try running in a different evaluation mode? 

R

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[mikael persson]

you mean the DG stuff in prefs?

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[Ryan O'Phelan]

Yeah. I haven't looked into the collisions thing, but it seems that would be the first thing I would check. 

Frankly, I find it frustrating to rig, simulate, animate, with tools that error out depending on what evaluation mode you're running in. As I've said hundreds of times before, they need to rewrite Maya to be consistent and multithreaded. 

[mikael persson]

Thanks for the tip regarding evaluation mode, switching it to DG seems to sort it for now. Though I imagine that's no guarantee.

How do the rest of you handle these things in Maya? Once I tread outside of pure character animation and try I do something slightly outside of what I do normally, the house of cards that is maya these days comes tumbling down. Is it as bad as it seems or is it just that I haven't learnt to tread exactly in the correct path?

Mikael

[mikael persson]

That didn't take long. DG no longer does the trick.. Does anyone of you have any experience with getting nHair to work?

Mikael

[cal...@glassworksamsterdam.nl]

You're not the only one. We rely on other software for that and only use maya for the basics. 

On Friday, April 13, 2018 at 10:15:44 AM UTC+2, mikael persson wrote:

Thanks for the tip regarding evaluation mode, switching it to DG seems to sort it for now. Though I imagine that's no guarantee.

How do the rest of you handle these things in Maya? Once I tread outside of pure character animation and try I do something slightly outside of what I do normally, the house of cards that is maya these days comes tumbling down. Is it as bad as it seems or is it just that I haven't learnt to tread exactly in the correct path?

Mikael

On 12 April 2018 at 19:18, Ryan O'Phelan <desig...@gmail.com> wrote:

Yeah. I haven't looked into the collisions thing, but it seems that would be the first thing I would check. 

Frankly, I find it frustrating to rig, simulate, animate, with tools that error out depending on what evaluation mode you're running in. As I've said hundreds of times before, they need to rewrite Maya to be consistent and multithreaded. 

On Thu, Apr 12, 2018 at 10:59 AM, mikael persson <he...@mikaelpersson.se> wrote:

you mean the DG stuff in prefs?

On 12 April 2018 at 16:50, <desig...@gmail.com> wrote:

Did you try running in a different evaluation mode? 

R

On Thu, Apr 12, 2018, 9:54 AM mikael persson <he...@mikaelpersson.se> wrote:

while I'm at it. What gods should one be sacrificing to to get collisions at all times while using nHair? I haven't discerned a pattern yet, but it's really hard to get my nHairs to collide with meshes that I've told to be passive colliders. At first I thought it was a 2017 issue when 2018 seemed to be behaving. But that didn't take long for 2018 to start acting up too.

I've checked all the obvious places. But might be missing something.. Is this a know issue?

Mikael

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[David Johnson]

Hi Mikael,

Here are a few semi-random thoughts that may give you some more things to try.

nHair and nCloth are things I do all the time (maya 2016 on linux) and I don't recall having problems with collisions. But I do think that getting mayas nSimulations can be a bit of a black art sometimes, so I feel your pain.

SubSteps and max collision iterations on the nucleus. For nHair subSteps can often be quite low (eg 4), but you may want to try increasing the collision iterations a lot (eg 32) if your stuff is moving fast.

Collision geo. Evenly tessellated closed surfaces tend to work better than planes. Good normals? Are they facing out? Did you check the collision thickness on both the passive and the hairSystem? Make sure they dont intersect on the start frame.

nucleus space scale? Have you set it to something appropriate for your scene units/scale. eg modeling in real world scale with maya units cm, then set space scale to 0.01

I dont see too many problems working in parallel mode (but the fx guys tell me they prefer to work in DG mode).
Often we notice that when the nucleus is first enabled (eg open a new scene and import the hair rig) and you hit "play" the nHair will wig out completely. But stopping, rewinding and playing again will reset everything correctly.

How dense are your hair curves? I try to use curves with the least number of cvs that will look ok for my needs. Sometimes I then increase the "extra bend links" attr in the hair system to 2 or 3, depending on how it is behaving.

Are you using start curve attraction? At high values this will probably override collisions.

Do you have more than one nucleus in your scene? And if so, have you used the same objects as passive colliders for more than one nucleus? I have never got that to work properly. I mean, maya lets you set it up that way, but then it just ignores collisions for all except one nucleus. So I simply use duplicates and assign one to each nucleus.

Let me know if you want more details on these or other issues. Happy to help if I can.

David

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[mikael persson]

Thanks a lot David! I'll be checking out all of this during animation today. 

This is exactly the stuff I was hoping for. So much of this comes just from experience.

My scene is two strands of hair that go over two cylinders two meters above the ground and through a torus at ground level behind. The strands at the front are connected to two objects. So it's a fairly simple setup.

So far the best method to get this working is simply to restart maya and hope that it works.

Mikael

[ryan harrington]

In case it helps, I've had very terribly BROKEN LOOKING nhair solves that perform just fine in the legacy viewport.

Good luck