View Full Version : Head w/ maya 6 Hair rotation

09-15-2004, 02:13 PM
Hello all,

My setup is as follows:

Hair grown from Scalp, Scalp Parented to Head Bone

When I rotate the head bone the hair does not follow through during the rotation. For example, when the head rotates from right to left, the head will rotate and end up looking out from the side of it's hair. The hair will flop around but not crisply rotate as it should. I have been trying different dynamics settings but I am not sure how to fix this issue. Should I be using constraints? How should I setup my dynamics field?

Thank you!

09-15-2004, 02:39 PM
Here is an image showing what is happening.


09-15-2004, 04:19 PM
Create a collide sphere constraint on all the hairs and parent this to the head, scaling it to
match the size of the head. It can protrude in front of the face a bit, but make sure it doesn't overlap the hair roots. You may also wish to create addition collide constraints for neck, shoulders and possibly the nose(the collide constraints are generally preferrable to geometry collision).

To keep the hair somewhat attached to the head near the root you can create a transform constraint on all the hairs. Parent the constraint to the head and make the pointMethod = Uparameter setting the Uparameter to 0.2 or some value near the hair root. This is like pinning a point partway down the hairs to the head. You can lower the stiffness on the constraint so that this looks more natural. Also you may wish to create additional transform constraints with different Uparameter values.

Also make sure that gravity is high enough for your scene scale.. if your head is large then gravity needs to be increased. The default gravity value is too low for most scenes.
You may also need to increase the stiffness a little, and possibly use rest curves.


09-16-2004, 02:24 PM
What do you mean by a "collide constraint"? Are you talking about a seperate object other than the characters head? Or an actual constraint option you can choose in maya, like aim, orient etc.? - Thank you!

09-16-2004, 05:22 PM
Under the hair menu:
create constraint->collide sphere (or cube)


09-17-2004, 05:12 AM
This is great. I can now animate the hair as it should move.

I am having caching problems now : "cache is not open"

Any ideas on this? When I go to save the scene I get that message... no batch render.

I know this has been talked about before, I am just not finding the right answer...

09-17-2004, 08:17 PM
I've not had this warning message, but is sounds like there is a problem copying the temporary playback cache to the permanent cache. If you had permission problems on the cache directory it could cause problems.. or perhaps it is overwriting a previous cache that
is not writable. Another problem could be if you have problems with the pathnames for
the cache directories.. certain characters don't work well.


09-18-2004, 02:06 AM
Thank you for your help Duncan.

I am also getting the error message: "Need a unique name among all disk caches."

Any ideas here?

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