tail animation

[leach]

whats the best method you people have found for animating a tail on a monkey, for example.

at first i thought maybe IK, but it does that funny flipping thing when it goes past its own origin, if you get what i mean, also only bends in one direction.

i'd also like it to be able to follow behind properly, eg, follows the arc of a jump. there are quite a few differnet ways i guess, id just like to know what you lot recommend.

thanks

leach

[fredc]

Q: IK flipping when going past origin.
A: This is called "gimble lock". Basically it means that two solutions are possible and software is giving you the one you don't want. You can use Skeleton/UpVector Costraint to contol the plane that the skeleton moves in. Just place a null on the side you want it to favor, then select the first bone of the skeleton (not the base), then select the command. When you move the Null you will effect the plane that the skeleon moves in. This is helpful for controlling the "roll" of an arm. If you hold the wrist your wrist stationary and then move your elbow you will see the need for this, since moving the effector of a character's wrist won't do it.

Q: IK only bends in one direction.
A: Yes, IK solvers in 3D animation products lock at 180 degrees. Believe me, if they didn't you would find them very hard to control.

Anyway, here is a couple of options, and there are probably more, but these should work.

1. Use single bone skeletons and constrain each base to it's adjacent effector. This way you can move the effector in any direction you want. Of course this motion is localized, but the bones will deform your envelope.

2. Use a curve deformation to deform the geometry of the tail to a curve. Then use shape animations on the deform curve to make the tail move.

Note: If you haven't used curve deformation here is a hint: The geometry to deform assumes the "length" of the object to be Y. Thus if you had a cylinder positoin it around the 0,0,0 axis so that it is standing up in the front view. Then use Effect/Freeze to lock it's transformations. Use Deformation/Curve/Create and place it on the curve. When translating use local instead of drag to move it in Y along the curve. You can scale and rotate relative to the curve as needed. If you want to reposition it before you start again, use Deformatoin/Curve/Deactivate to temporarily take if off the curve. Use Create again to automatically place it back again. If this feature is giving problems, practice it for a while. It is very simple with practice. Use the documetation too. Always use Deformation/Curve to make Extrusions follow curves if the curve is going to animate.

Hope this helps,
Urp

[leach]

cheers for that urp.

about the up vector, i know how to use them, but i thought they were only applicable for skeletons with only two bones i.e. a leg or arm. the tail would require quite a few more than this. was i wrong to assume this?

i was wondering, using your method of single bones constrianed to another bones effector, would it be possible to then have the effectors follow a curve and get a whip like motion, ie, a sine curve, moving along the tail?

i'll try some methods out and see which works best for me.

cheers urp

leach

[fredc]

Leach,
The upvector controls the plane that a skeleton moves in, so it will work for any number of bones. In all cases you identify the first bone to apply the constraint. You can also have an upvector automatically created with Skeleton/AutomaticUpvectorConstraint. Although, you wouldn't need UpVectors constrained on every skeleton on a charcter.

Q: would it be possible to then have the effectors follow a curve and get a whip like motion?
A: Yes. Let me know if you need some assistance in this.

Good luck with your project,
Urp

[leach]

urp, cheers for clearing that up for me, and yes, i would like some assistance very much on the matter of the whip like animation.

normally i would try this my self first, but i really dont have the time at the moment. it's currently 5 in the morning and im still plugin away at soft for my uni project!! but ya gotta luv it

thanks for the offer urp. i just had a thought, surprising seeing how late it is!!, would you mind if i put your responses into my report for research purposes? just thought i should ask.

leach

[fredc]

Leach,
Here is is the method I use to constrain skeletons to curves. If you need more information just ask.

1. Turn on your grid lock. (Shift S).

2. In the Front View Create a skeleton with the number of bones you need. Make them verticle and use the grid lock to keep them similar, but this is up to you. You might try this on only two bone skeleton first.

3. Create a Linear Curve next to the skeleton with a point corresponding to all the base, joints and effector of the skeleton.

4. Constrain the skeleton to the Linear curve by:

5. On the Linear Curve tag the point for the effector.

6. Make a cluster with Model-Tag/SetCluster (you an use default name).

7. Select effector and use Constraint/Object to Cluster and select the Linear Curve. This will constraint the effector to the curve. If you mess up use Constraint/Relax to remove the constraint.

*Select the next point on the Linear Curve (be sure other point is unselected), and use Model-Tag/SetCluster to make another cluster.

*Now select the bone next to the effector. Note: When you constrain bones, the large end is what is constrained. Then use Cosntrain/Object to Cluster again and select the Linear curve. The large end of the bone will constrain to the current cluster (point).

*Repeat for other bones.
On the last bone, don

[leach]

that sounds great urp.

thank you very much for your time, its greatly appreciated.

leach

[fredc]

Leach,
Glad to help. A couple of items I forgot to mention.

1. The hotkey to turn off Grid Lock is .

2. Ghost View: This might be a good time to check out the Ghost Display for you Viewport. Where you select Wireframe and Shading for you viewport, you will see Ghost in the list. When you select this you will see an onion skin of frames before and after you current frame. This helps to refine you motion, since you can see it progress through time. Use Setup on the Ghost view to change how many views before and after etc. You'll love this command when trying to keyframe the feet on a walking character.

Urp

[fredc]

Sorry for this addtional post, but apparently the brackets I used around the buttons for turning off the grid lock are used for formatting html. Therefore it didn't print the text in-between. Anyway I will repeat it again without the brackets.

The hotkey to turn off Grid Lock is Shift + D.

Urp

[leach]

thanks alot for the additional info urp.

it's just in time too as im about to start animating a character and it will come in handy. i can see it being usefull for finding where an animation jumps unwantedly on single frames.

cheers budy

leach