Hello,
I've been experimenting with an IK chain of rings arranged  in the form of a
segmented tube (see "segmented helix?"). I'm fairly satisfied with the
results so far, but I would like to limit the amount of curvature in the
chain, so there will not be any really tight bends, only graceful curves.
What adjustments should I make to achieve this? I have almost no experience
with IK, so I suppose I could be missing something very obvious. It appears
to me that to change the modify settings, I have to change them for each
individual CSG, so changing settings without knowing what I'm doing would be
prohibitively time-consuming.
Thank you,
Steve Shelby

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Hi Steve Shelby, you recently wrote in moray.win:

> What adjustments should I make to achieve this? 
On the screen where you specify that the object is part of a CSG (the
Modify button on the Modify Tab) you can limit the rotation about the
axis of the axis that are taking part in the IK chain. Limit the
rotation to, say +- 30 degrees for each joint. Also, you might want to
make the dampen value smaller (say 0.2), so that the rotation
propagates down the chain more before the top end elements are
completely rotated...

It's best to try setting up a chain of say 4 or 5, and then using
Copy/Paste to duplicate the chain.

- Lutz
  email : lut### [at] stmuccom
  Web   : http://www.stmuc.com/moray

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Oh, by the way, Lutz,
What does the 'dampen' really do? I have never well understood its
function....

Thomas


"Lutz Kretzschmar" <lut### [at] stmuccom> schreef in bericht
news:s02i5ugnmqr7ovpd54e9tsd76kiuh5n9e4@4ax.com...
> Hi Steve Shelby, you recently wrote in moray.win:
>
> > What adjustments should I make to achieve this?
> On the screen where you specify that the object is part of a CSG (the
> Modify button on the Modify Tab) you can limit the rotation about the
> axis of the axis that are taking part in the IK chain. Limit the
> rotation to, say +- 30 degrees for each joint. Also, you might want to
> make the dampen value smaller (say 0.2), so that the rotation
> propagates down the chain more before the top end elements are
> completely rotated...
>
> It's best to try setting up a chain of say 4 or 5, and then using
> Copy/Paste to duplicate the chain.
>
> - Lutz
>   email : lut### [at] stmuccom
>   Web   : http://www.stmuc.com/moray

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Hi Thomas de Groot, you recently wrote in moray.win:

> Oh, by the way, Lutz,
> What does the 'dampen' really do? I have never well understood its
> function....
IK works in such a fashion that it starts at the selected object and
looks at the parents until it's at the top. At each parent, it looks
which axis (rotation or translation) are available and sets the value
in such a way that the selected object comes as close to where it
should go as possible. This is repeated all the way to the top and
then it's repeated until the selected object is within a certain
distance to the target
(View|Configuration|Advanced|MaxTargetDeviation) or this has been
repeated the maximum number of times
(View|Configuration|Advanced|MaxIterations).

At each step, after Moray has calculated the optimal change in
rotation or translation, it limits this movement to the value in the
dampen field. So, take your arm as an example. Say that to get your
fingertip to a specific point, you could turn your wrist up by 60
degrees. This would mean that the elbow would harldy move and the
shoulder not at all. If dampen is set to, say 10 degrees in each
joint, the wrist will only be rotated 10. Then the elbow will be
rotated at most 10 and the should also. This is repeated until the
target point is reached.

The effect a lower dampen value has is to make the movement 'softer',
i.e. to rather propagate the movement up the IK chain than to make
extreme movements at the bottom of the chain.

Clear as mud, eh? Questions?

- Lutz
  email : lut### [at] stmuccom
  Web   : http://www.stmuc.com/moray

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Hi Lutz!
This is surely a less than muddy answer!!!
It might even answer some puzzling things I had with IK and that I could not
figure out. I shall have a try at it again. No further questions for the
moment...
Thanks a lot indeed!!! (also on behalf of all those IK labourers around the
world)

Thomas

"Lutz Kretzschmar" <lut### [at] stmuccom> schreef in bericht
news:4vkk5uc5tvc7sg7q4knu0qsjv0ujl574t2@4ax.com...
> Hi Thomas de Groot, you recently wrote in moray.win:
>
> > Oh, by the way, Lutz,
> > What does the 'dampen' really do? I have never well understood its
> > function....
> IK works in such a fashion that it starts at the selected object and
> looks at the parents until it's at the top. At each parent, it looks
> which axis (rotation or translation) are available and sets the value
> in such a way that the selected object comes as close to where it
> should go as possible. This is repeated all the way to the top and
> then it's repeated until the selected object is within a certain
> distance to the target
> (View|Configuration|Advanced|MaxTargetDeviation) or this has been
> repeated the maximum number of times
> (View|Configuration|Advanced|MaxIterations).
>
> At each step, after Moray has calculated the optimal change in
> rotation or translation, it limits this movement to the value in the
> dampen field. So, take your arm as an example. Say that to get your
> fingertip to a specific point, you could turn your wrist up by 60
> degrees. This would mean that the elbow would harldy move and the
> shoulder not at all. If dampen is set to, say 10 degrees in each
> joint, the wrist will only be rotated 10. Then the elbow will be
> rotated at most 10 and the should also. This is repeated until the
> target point is reached.
>
> The effect a lower dampen value has is to make the movement 'softer',
> i.e. to rather propagate the movement up the IK chain than to make
> extreme movements at the bottom of the chain.
>
> Clear as mud, eh? Questions?
>
> - Lutz
>   email : lut### [at] stmuccom
>   Web   : http://www.stmuc.com/moray

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