Cineversity

I’ve assembled the attached wind toy and need some guidance as to what the options of animating it…

I’ve assembled an ik rig and am getting close to the results I want, but as you can see “StapleJoint” moves on the Z axis, I’m unsure how to stop it. Also, the constraint tag on the ScrewJoint_Goal is consistently 1 frame behind when animating. I know it’s a priority issue, but can’t recall the proper remedy.

I’ve tried multiple Xpresso setups, but my math skills aren’t sharp enough. I’m unsure how to limit the woodpecker from 0 degrees to 20 degrees when referencing from an object that spins at a constant growth of degrees, then have it retreat back to 0, and repeat. Hopefully once you see the scene more sense will be made.

So I’m sure this can be done both ways and maybe it’s a matter of preference, but I can’t get either to work so thank you for any assistance.

Thank you,

Hi Andy.Man.

Certainly a “Priority” problem. My advice, reduce the amount of redirecting. Each constrain needs to be evaluated: Kai Pederson has created a clear an complete overview about constrains here on Cineversity.

The Constrains have as well an option to limit the information flow: Attribute Manager> PSR> Constrains. With switching of information,e.g., P.Z—you get the bird stable on Z, but of course it might not resemble then a rotation path anymore.

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My suggestion, as the core element is the axis: This is the only element that needs to be animated. Which eliminates the “Whirligig” and one XPresso set up. One less. From there you can retrieve all information directly, one “link” only. Leaves the Rig itself (joints and IK) this needs a higher priority, as the information that is received later will overwrite anything earlier. In the tutorials you might see also the position in the Object Manager is crucial most of the time.

There is not just a one click remedy, sorry. Priority is part of the skills set one needs to have. Or, and I continue with my personal idea, I would try to set up a formula to get the “piston” like movement.
To introduce many elements increases the complexity naturally. The same is true for XPresso nodes. If you would have one only, the priority organization is much simpler for that. In the XPresso Editor> X-Manager> X-Pool it should move top to bottom. Mostly it doesn’t need to be sorted, but any information that is not produced so far, is mostly then replaced by the one a frame produced before, etc. I have seen questions here with over three frames delay, based on just using one XPresso Tag after the next.

Let me know if I should look into math based solution.

All the best

I have attached a Axis-Rod-Piston set up in XPresso. Have a look into the file.

On one end you can attach the windmill, it is rotating based on the Cylinder R.B.

The Piston is where the beak would be placed. This allows then for a direct movement of the bird.

The idea was to follow closely the concept of the core information and the shortest way for this information, as the piston is here the “goal” of the IK.

(All orange parts are only for illustration purposes.)

Click on the XP_Piston object to get to the User Data. The rod should be always longer than the radius of course.

The second file is just a “slap-comb” to show the simplicity. No Joints, no constraints, only one XPresso and on Target Tag. Between beak and piston a lose “wire” with a target should do, as in reality, it is something that is not tight.

(A simpler version would be possible, just with a rotating axis 90º to the main with a Null in the right distance to the axis as target for the bird. No perfect, but fast and easy)

OR mainly based on a formula which I have created for the piston move “((sqrt(sqr($4)-sqr(sin($1*180/PI)*$3)))+(cos($1*180/PI)*$3))+$2”
https://www.amazon.com/clouddrive/share/VI7SibTLPlvwYqVIz2F9YfoxddJ0nMWisvlz-u_EkUQ?ref_=cd_share_link_copy

P.S.:

Here is you file with all parts needed to have it function. I animated only the “Turn” object and avoided as much information detours as possible. If you like to stick with all the Tags and priorities, please check out the above mentioned tutorials.

The User Data works as above, the Radius needs to be adjusted to the “wire” object in your scene, which I did already ( the orange circle aids that process). The Rod parameter adjusts then the distance to the bird. I saw that my previous example assumed the bird would turn the wheel, but that is hopefully only a small change. It picks on the main element based on the wind now.
Based on the rotational movement of the bird, the formula would be more complex. But the little link between “wire” and bird has some tolerance, and so I left it on this level.

I hope you like it, and if you have any questions—let me know.

All the best

Very good, Doctor. I’ll have a good look at this. Thank you as always!

Great, thanks for being open to explore it, Andy.Man

You have certainly no problem to apply all kind of techniques. That is good by itself.
My main target is of course that all of the problems you mentioned will be no obstacle for you in the future.

I hope my philosophy of keeping it simple will show some value. As usual, I think the information flow in C4D is a key core concept to follow, to solve problems.

Keep it simple—and then use a formula like this? Well, I hope the little sketch puts it a little bit apart already. This is how I solve such things, by breaking it down in simpler parts.
Once you see the single parts, the piston formula looks pretty simple; Perhaps now it is looks just cryptic.

Let me know if there is a question.

All the best