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Dynamic transition jerking
Posted: 10 August 2019 08:50 AM   [ Ignore ]  
Total Posts:  76
Joined  2013-11-16

Hi

I have a test file (35MB - please send me an upload like) where elements of a figure become dynamic and float away. At frame 50 I use a dynamic transition (dynamic on to off and transition time 50) to return the elements to their original position. It works OK except that at frame 50 the objects jerk (mainly sudden large rotation) before beginning the transition. File is cached and changing solver steps doesn’t help. Help!

Also, is there a way to do this with Xpresso where I can have more control of the transition (ease in ease out etc).
Could your also please check the character as I’ve used parenting to attache items to joints and a fracture object to allow me to use a single dynamics tag - looks a bit dodgy to me although it seems to work. BTW removing the parenting tags doesn’t affect the jerk at frame 50.

Thanks
Chris

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Posted: 10 August 2019 11:04 AM   [ Ignore ]   [ # 1 ]  
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Hi Chris,

Thanks for offering a file, the upload link is in your Cineversity Private Message. DropBox alerts me when something arrives. I will have a look at it.

Cheers

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Dr. Sassi V. Sassmannshausen Ph.D.
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Posted: 10 August 2019 11:12 AM   [ Ignore ]   [ # 2 ]  
Total Posts:  76
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Uploaded Thanks.

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Posted: 11 August 2019 04:40 AM   [ Ignore ]   [ # 3 ]  
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Good Morning Chris,

I have sent you a link with two versions. Please have a look.

Since the dynamic is only short, and its second part is mainly to ‘reset’ I have included a second option, which I think allows for a much better art direction that Dynamics does. For anyone else reading along, the Character partially explodes, and after a short time, all parts fly back to the original state.

I find to use the Target Effector, set to Repel, as well as some other Effectors (Random and Delay) to produce a similar effect. As you are the art-director, you might tweak everything, of course.

The Dynamic part, as you can see, is now without any of the jerky rotations. I just increased for a moment the Force: Follow and Damping parameters.

Xpresso has no options to Ease-Ease that Transition time.

The Constrain Parent Tags are all set to Priority Expression 0, for the members of the Fracture Group. It should be a tiny little bit higher than the Priority of any related object in the Character Set up if the Character is not run by an Animation Clip. Perhaps, select all of these in the Fracture group, select one a single object, and Main Menu> Select> Selection Object. (In the list, delete the object, as it is the work-around dummy to get a tag-based selection)

Now you can quickly reselect all fo those, and perhaps set them to Expression 50, while checking the refresh boxes Camera / Frame). You need to know the priorities of your project, that is part of the job. Write them down on a piece of paper, like a tree, so what comes first (trunk), second (branch), third (Twig), etc. This just works, I know, but it needs to be done by the artist; otherwise, you will run in a life long dependency.

Please have a look at the example file, which represents a simplified set up of your scene. I did not use any transition here. The Dampening was set to 100% where I liked to have the return of the clones later on. (Just to be clear, I do not expect a ‘return’ from the Dampening, it is just a preparation.) Then The MoGraph Cache was used. Explore the Playback tab for the exact setup. You can’t set any curve on this directly, but you can set more or fewer keyframes to shape an ease-ease behavior.
Scene file
https://www.amazon.com/clouddrive/share/HfEh6i8f6hBsQl8x3KIWGlY0W8HEcAo3QAkgVKqxrz9

All the best

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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.
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Posted: 11 August 2019 05:47 AM   [ Ignore ]   [ # 4 ]  
Total Posts:  76
Joined  2013-11-16

Thanks as always.

Using the cache offset is an interesting approach - I will fiddle with that.

I had tried key framing the follow position/rotation with similar results as your example - Unfortunately in your example, the jerk is still there at frame 50, just less noticeable and as I want to do a very gradual/slow animation this will not give an acceptable result.

I also tried mograph effectors for the animation but because there is no collision detection the objects overlap at times - again not acceptable. Because the push apart effector is based on radius not object shape this doesn’t work. I also tried using mograph effectors and dynamics tags with animated follow position/rotation to give collision detection return to position that sort of worked.

I just hoped there was a simple fix of the dynamic transition jerking as that was the simplest option.

Cheers
Chris

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Posted: 11 August 2019 05:59 AM   [ Ignore ]   [ # 5 ]  
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Hi Chris,

You’re very welcome.

In a Fracture Object, the clones will go back to their initial position and rotation, while moving through the transition. Any rotation that was done before will have the need to be “re-winded” before the end of that transition.

Since that is a process without any great option to control, I typically do not suggest or even use it. Yes, I tried to keep the little options that are given as low as possible. Anything strong looks not natural to me. Please explore how much you might find acceptable. I can’t do that for you.

Yes, the collision is not a given during a pure non-dynamic MoGraph set up. I have no idea about your final use of it, and how much motion blur you might use (which will hide some of the problems). Yes, if the collision is a must-have, I can only suggest the Cache set up. Dynamics are the least art direct-able animation form. That is the nature of it.

Enjoy your start of the week.

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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.
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Posted: 11 August 2019 06:15 AM   [ Ignore ]   [ # 6 ]  
Total Posts:  76
Joined  2013-11-16

Thanks

I’ve sent you a test using a random effector, follow position and a dynamic transition just at the end.

It gives good control, has collision and no visible jerking (as objects are nearly back to their original position by the time the transition starts). What do you think?

Cheers
Chris

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Posted: 11 August 2019 06:35 AM   [ Ignore ]   [ # 7 ]  
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Thanks, Chris, for the file.

Looks good! Thanks for sharing. I hope this will do it for you.
As mentioned above, this is a complex setup/project where the art-direction is certainly key.

My best wishes.

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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: 11 August 2019 02:04 PM   [ Ignore ]   [ # 8 ]  
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P.S.: talking about art directing, I wanted to share this with you.

The idea is simple, create the dynamic motion you are after, cache it, and offset the cache in the way you like.

Then use that motion and share it with another Cloner, and use any effector you like, e.g., the Delay Effector, to ‘blend’, ‘even’ or have it ‘spring’.

See file below:
https://www.amazon.com/clouddrive/share/YLoorfHXq8lrQCtUiqNc1eEENrdJpIyS1SORHprd9jA

Enjoy

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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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