IK and Path Constraint

FogRyu

Hi everyone. I've got a small question.

Can we use path with Ik constraint in some way ?

Imagine a character with a snake like neck made with a path. If we want him to move his neck and body randomly but we want his head to be in a fixed position, can we use a path with a IK constraint on his head ?

Or, in another hand, if we want the head moving on a path and the snake like neck following the head by agjusting his lengh automaticly, it could be great to have two path working together (Neck + head) with a IK constraint to the base of the neck on the body.

Can we do that ?

Thanks !

Søren

You can use IK Constraints together with Path Constraints. In some cases you will need to manually change the order of which the constraints are calculated.

Please see Constraints for some more information on constraints.

FogRyu

Ok thanks !

But i think i wasn't clear enough.

What i try to do is to have a bone "in" a path having a constraint.

And also, i search a way to animate a path with bones. For example, it'll be cool to have one path with multiple bones in it (Let's say 30 for example) and two bones at the extremity. And i try to find a way that if i move those two bones, the path will follow the movement. Can we do that ?

Thanks !

Nate

Multiple constraints can be applied to the same bone. You can set the order of the constraints by dragging them in the tree. If you control a bone with a path and an IK constraint, you probably want to have the path only control translation by setting the rotate mix to 0, then the IK can control rotation. Otherwise if you apply the IK constraint, it sets the rotation, then you apply the path constraint with a rotate mix of 1, it will also set the rotation and it will appear that the IK constraint did nothing.

FogRyu

Ok thanks.

So it can work for example with differents bones following a path and a transform constraint between this bones to control the rotation. Like a tank tread for example.

But let's say for example the character i talk before, with a long snake-like neck (arround 20 bones long). Can we do his neck in a path, while having IK constraint on the two bones at the extremity of the path for the head and the body ? What i want is to move the head while not moving the body for example (Or the opposite), and the neck follow the movement.

And i'm not sure Nate explanation can be apply to what i want to do.

Thanks.

Nate

It's hard to envision, but yes that sounds possible. It's easy for you to try out by first rigging the bones without any images.

FogRyu

Hmm ok thanks.

I'll try in different ways.

Thank you

Søren

Try taking a look at the stretchyman example.
The legs use paths and IK.
First a path is weighted to two IK bones.
Then a path constraint is used to constrain eight bones to the path.
Lastly a mesh is weighted to follow the eight bones constrained to the path.

Try moving one of the IK targets for the legs to see the result. Note the setup for the actual Path Constraint. Setting it up this way will also allow you to stretch the leg.