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Joint Rotation Problem on Spline Dynamics
Posted: 04 June 2019 03:12 AM   [ Ignore ]  
Total Posts:  292
Joined  2017-09-24

Hi,

I have a joint chain driven by spline dynamics.
The problem is when I reset back to zero out control and at frame 0, there is a nasty twist on the joints rather than being on the default rotation.

You can see an illustration video of the problem here:
https://www.dropbox.com/s/vcmhheee3ebhsga/c4d100_rotation_error_spline_dynamics.mp4?dl=0

My solutions so far were
1) Reorganize the priorities, which I think I solved since there are no longer delays on the joints and the controller.
2) Increase substeps (for the document and the tag)
3) Add a protection tag (set to lock on rotation), but the spline dynamics overrides this.

But the problem still persists.

Is there a way around this?


You can see the illustration file here:
https://www.dropbox.com/s/xd9g60z9i99y7xz/c4d100_rotation_error_spline_dynamics.c4d?dl=0

Thank you for looking at the problem

Ben

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Posted: 04 June 2019 04:53 AM   [ Ignore ]   [ # 1 ]  
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Hi Ben,

Please have a look at the file below, press ‘play’ if needed, and see my “stress-test” of the rig.

Scene file:
https://www.amazon.com/clouddrive/share/WeLQX027pIbab1Y016rXuwGbCaQl2z325PaCRgoH4tS

Key features: Sweep

• Use Rail Direction on
• Use Rail Scale off.

All the best

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Dr. Sassi V. Sassmannshausen Ph.D.
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Posted: 04 June 2019 11:43 AM   [ Ignore ]   [ # 2 ]  
Total Posts:  292
Joined  2017-09-24

Hi @Dr Sassi.

EDIT: Not working
Please see comment below

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Posted: 04 June 2019 11:48 AM   [ Ignore ]   [ # 3 ]  
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Ben Traje,

If the Sweep object doesn’t give you what was shown in your file (Hose), what do you need the Joints for?

Cheers

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Dr. Sassi V. Sassmannshausen Ph.D.
Cinema 4D Mentor since 2004
Maxon Master Trainer, VES, DCS

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Posted: 04 June 2019 11:52 AM   [ Ignore ]   [ # 4 ]  
Total Posts:  292
Joined  2017-09-24

The joints are bound to the actual model. The hose with a sweep is only a simple representation.
The actual model is much more complicated hence I need joints.

Will get back to you about the progress.

Thanks for the reply!

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Posted: 04 June 2019 12:33 PM   [ Ignore ]   [ # 5 ]  
Total Posts:  292
Joined  2017-09-24

Unfortunately, the joint still rotates incorrectly.
You can see the illustration file here:
https://www.dropbox.com/s/8ri3i092ihs161j/c4d100_rotation_error_spline_dynamics_v1.2.c4d?dl=0

Press Play and go back to the first frame

See also attached on the resulting mesh.

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Posted: 04 June 2019 12:34 PM   [ Ignore ]   [ # 6 ]  
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Thanks, Ben, for the additional information. ( Edit: This is a reply to post #4, but it should answer #5 /edit)

I was looking for the simplest solution, hence the Sweep Object solution. Since I know now that the Joints are the key element in this question,

Have a look into these files:
https://www.amazon.com/clouddrive/share/P5IACRYyb8Ih72MbroYNd5owWlMl0b20MgJIsSxzhl0

The first one introduces two handles, which prevent the twist for the B axis.
The second used your spheres as handles. I made a screenshot to show the details.

The point numbers of the Spline is crucial information (Activate the Spline, then check the Structure manager)

As before, I have recorded a stress test, and over 1000 frames, there is no problem. For the final version, perhaps use the Point Cache.

My best wishes

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Dr. Sassi V. Sassmannshausen Ph.D.
Cinema 4D Mentor since 2004
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Posted: 04 June 2019 05:31 PM   [ Ignore ]   [ # 7 ]  
Total Posts:  292
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Thanks for the response Dr. Sassi!
Your technical skills always amaze me.
This should work

Have a great day ahead!

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Posted: 05 June 2019 01:06 AM   [ Ignore ]   [ # 8 ]  
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You’re very welcome, Ben, thanks for the kind feedback.

This thread shows clearly that I answer in Fora for a long time. You have asked a direct question, and I tried to find the smallest and most straightforward setup, going by previous questions of yours: But it was about joints after all.

So, I thank you for your patience, as I certainly know that I’m a little bit too much trained to try to find what is really needed, and sometimes that is just exactly what it is, going by the question.

My target is also educational. I love to share anything that is needed, given that tutorials are used here first, to create over time an excellent base to work from. I have no reservations to pay forward or limit my flow of information. Yet, I learn every day as well. In a nutshell: I love to learn and to share.

The wish to provide simple solutions, so the project work is more efficient, can create a little bit more elaborated path towards it. Thanks for playing along.

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Dr. Sassi V. Sassmannshausen Ph.D.
Cinema 4D Mentor since 2004
Maxon Master Trainer, VES, DCS

Photography For C4D Artists: 200 Free Tutorials.
https://www.youtube.com/user/DrSassiLA/playlists

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