Hair and Hair Collieder

[Adam Trachtenberg]

You have to run the animation forward in order for the dynamics to take effect, even if you’re only rendering a single frame. Once you do that you can, if you like, freeze the hair with the Simulation>Hair Edit>Set as Dynamics command.

[Tony Barone]

Thanks again for your help Adam, but I’m still not able to get the thing to work.

I’ve attached my file, can you let me know what I’m doing wrong here?

Note: I’ve set the hairs pretty low just for testing purposes to get it to update faster.

3524_hairtest.zip

[Brian Jones]

you’ll have better success if you turn off the colliders then let the grass fall through the floor then reverse the gravity and then let the grass rise up to deflect off the colliders (turned back on).
Still that’s not going to be real successful since there is too much space between the points of the landscape and since the hairs average themselves between the guides if you have a guide to the left of the shovel and the next is to the right all the hairs in-between will go right through the shovel. So if you make the landscape mesh denser then redo the hair on the new object and do the fall/rise thing it would be a start.
A couple other things (other than playing with the collision settings) you can do is make the dynamics affect the hairs and not just the guides (slower but more accurate) and since you will still likely get some hair penetration, you can also use Proximal in the Length channel of the hair (set to the tools) to make the hair right under the tools shorter.

[Tony Barone]

Thats obviously all I want, to make the grass beneath the tools shorter, or “pushed down” by the tools.

I tried the proximal in the length, but that make the grass disappear entirely for some reason, I put the tools into the “objects” portion of the proximal settings.

[Adam Trachtenberg]

A more direct approach would be to animate the tools actually moving down the ground. Do it slowly to lessen the chance of penetration.

I agree with Brian that you’re going to have penetration issues with so few guides, but instead of using hair-level dynamics you can also increase the guide count. Worth a shot, anyway.

[Tony Barone]

I think part of my question is being missing, or I am not asking correctly…

I am having trouble with the collision settings. Whatever I seem to set them at, they don’t make a difference with the hairs.

I have the hairs set to a low number just for testing purposes as higher settings slow things down tremendously.

Can someone please explain how my collider settings should be to effect the hair? This is my first time ever using the hair features.

Thanks.

[Adam Trachtenberg]

I don’t think the collider settings are going to make much difference. You probably need to adjust the dynamics settings in the hair object. Presently you’re using very stiff settings. The “ridgid” checkbox makes a very big difference in terms of stiffness. With that checked you might need to lower the actual stiffness parameter to 10% or lower.

[Tony Barone]

ah… I’m starting to see. Didn’t realize I had rigid checked, thanks for pointing that out. Guess in my trying to figure this thing out, I figured they should be rigid.

Things are starting to get to where I want them.. I think.

I setup a short animation of the tools slowly falling onto the ground, as you suggesting and that seems to be doing the trick. Still, some hairs are poking through the shovel for some reason. Any idea how I can prevent that?

Also, when its where I want it to be. Is there a way to “freeze” the grass into the position its in and save it that way, so in the future I wouldn’t have to re-run the animation to get it there?

[Adam Trachtenberg]

The grass poking through could be a result of too few guides, if you’re applying dynamics to the guids rather than the hairs. Or it might be the result of settings in the hair material which aren’t calculated when dynamics are applied to the guides.

You can use Hair edit>Set as Dynamics to freeze the hair position. If you do that you’ll then want to turn off dynamics to prevent further motion (and to speed up the display).

Rather than go round and round adjusting parameters, I would just get the hair close and then use the brush and other tools to push penetrating hairs back under the tools.

[Tony Barone]

Where is “Hair edit>Set as Dynamics” ?

I’ve looked just about everywhere I can think of. I’m using C4D R13.