Link Constraint - move animation in time etc.

[Anonymous]

I'm making an animation with several objects that are successively handled by different devices. A simplified version of the animation is attached herewith.

The objects are animated with a Link Constraint. This requires a lot of error prone clicking. Morevover, this makes the animation totally inflexible because the link times are not keyable.

When I want to move the animation in time or timestretch it, this requires adjusting all the link times by hand.

Why is the link constraint not keyable? Is there an alternative?

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10167_HwGMFnwLxU4sKE9v2n9v.zip

[Anonymous]

Anyone?

Please have a look at the file; isn't there some keyable alternative to the Link Constraint?

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[Tim_Wilbers]

First: Why not use a Tube primitive? Same result as a Circle > Extrude > Shell.

In order to have Keys to move in time you need to create the animation with one of the Key options checked in the Motion Panel in the Link Parameters rollout. (Functions described in the Help.)
I have not worked with the Key Mode except in the past 10 minutes to see if it would do what you need. It looks promising. You will need to test if you want Key Nodes, or Key Entire Hierarchy. Your procedure may need to be adapted.

[Anonymous]

I've know about the key options in the Link constraint for quite a while; they look promising but don't seem to do anything. There's no "set key" button or something like that.

The help file is no help too...

BTW the parameters of the pipes are given in (length,) diameter and wall thickness. The way I modeled it fits that description better than two radii.

MLB

[bthompson]

Hi,

I haven't looked at your example file, but I wanted to mention that a good alternative to using animated linked constraints is to use Position and Rotation constraints instead. Basically, you postition constrain and rotation constrain your object to all objects that you'd like it to link to. Then you animate the weight of the constraint at the appropriate times. This will give you keys to work with, and also allow you to smoothly pass the constrained object.

[Anonymous]

BradleyT,

Thanks, I thought about that too. The problem is that Position and Orientation constraints are always absolute (as far as I know); the constrained object will assume the position and/or orientation of the object linked to.

If you have a look at the attached file you will see that the lowering of the assembled pipe is done by alternatingly linking a single pipe section to world respectively to the vertically moving dummy (when it is going downwards). That way each single pipe section will increasingly advance downwards.

If you have an alternative solution to this, while avoiding the link constraints, I would be glad to hear it!

MLB

[scriptchimp]

You can check the "keep initial offset" option. It takes the initial position/orientation of the object
into account when adding the influence(s) of the constraint(s).

[Anonymous]

ScriptChimp,


I tried it; the only thing keep initial offset does is that it remembers the position of the object at the moment the controller is assigned to it.

When the object has to be "transfered" between the animated helper objects it still "jumps" from pivot to pivot (albeit with an offset...).

Very unfortunate...


MLB

[scriptchimp]

I get what you're saying...If all weights are zero and you give one a value it
"pops" to a new location. You could have a reference node for the initial
position of the object. This would allow you to transfer control smoothly.
You'd have to dial the previous weight to zero to be able to drive to the
next weight fully.

Like this...

1st weight 50 - Initial position
2nd weight 50 (halfway to 2nd position)
1st weight 0 - now at second position
3rd weight 50 (halfway to 3rd position)

and so on...
Kooky, but more flexible than link control.

Or am I missing something else?

[Anonymous]

ScriptChimp,

Yes that is the way i tried it; I gave each weight a boolean controller, making sure only one of the weights is "on" at a given time.

If you look at the animation in the original file you'll see that the pipes are linked to the vertically moving helper object when it moves down, when it moves up again the pipes are linked to world. This way each pipe moves downwards every n frames, thus the distance between the helper object and the pipe increases each time.

I'm afraid this is not possible using position/orientation constraints. But maybe I'm missing something...

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[bthompson]

It could still be done with pos/rot constraints. It's a bit of setup, and it's difficult to explain via text. If you need the flexibility to edit, it's probably the best way. I downloaded your example file and added an example of the pos/rot constraint method into it. The only tricky part has to do with the pipes progressively moving down. For that, I added a point helper to the end of the pipe, then constrain the following pipe to the point helper of the previous pipe. This is the only part where you'll have to change the constraints for each pipe, rather than simply clone and offset keys. The trick to the whole thing is proper alignment of the pipe pivot and each mover. Also, the mover's motion repeats via out of range key types.

I wish I had more time to explain it. Hopefully, the example file will help.

10690_00EVDuKYEgR4p0wx4La8.zip

[scriptchimp]

If you want the control to instantly go from one source object to the next, that should
work, unless I'm missing something (which I probably am). If you want "blend" control
try using a float controller.

I tried it with a simple setup, but with a series of objects as source (including a starting
source object) you can go from the initial position to what ever number you have.

[Anonymous]

BradleyT,

I can't open your file, probably because I'm using max 9. Never bothered to "upgrade", maybe when the link constraint is keyable in 3dsmax 2020...

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[Steve_Curley]

That's why it's a good idea to put your Max version (and brief system specs) in your sig - tends to prevent that kind of problem.

[Anonymous]

Steve you're right. Done...

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[Anonymous]

Editable keys for Link Constraint in 3ds max 2010. Finally!

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