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Stopping the Spline Wrap Deformer from Banking on a Tracer (Chris Schmidt Tentacles)
Posted: 03 November 2016 01:54 PM   [ Ignore ]  
Total Posts:  10
Joined  2016-10-27

Hey,

I have a dynamic chain of cubes that are connected by ball/socket connectors and springs - this chain dynamically follows a target object, like a tentacle.

I used the tracer to draw a spline through these cubes as a path for the Spline Wrap deformer to stretch a model of a tentacle across it, but when I use this deformer, the model banks and spins unnaturally upon sudden movement…

I tried fixing this problem by constraining cubes to the PSR of the original chain segments, locking their Up Vectors, then applying a protection tag to disregard all of the chain segment rotations and only allow XYZ movement - essentially I end up with the same chain, except the segments are locked facing upwards so when traced again the points aren’t full of rotation values… Still getting weird banking - even after using this as a rail spline too!

All I want, is to be able to use the Spline Wrap deformer and have the tentacle’s suckers facing upwards (towards the target object) the whole time without random twisting… I was thinking that maybe I should rig it with joints instead of the Spline Wrap Deformer… Would that keep the segments facing the right way up? I even set the Up Vector on the deformer settings - no luck!

Looked online and not found a solution. I’m sure it’s easy to do. Would love some advice on Spline Wrapping tracers without twisty artefacts!

The scene file is here for you to have a look at - https://drive.google.com/open?id=0Bw4AQ_iwgwBpZ0VkdlJjNDVweE0

Many thanks

Hayden

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Posted: 03 November 2016 02:23 PM   [ Ignore ]   [ # 1 ]  
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Hi Hayden,

Here is your file back.

A Rail is needed to give the tentacle an orientation. The Rail works like a target object.

Since the file was nicely set up, and the idea of Chris works so great, it was easy to produce a Rail based on the given elements.

I took all “Bone Cubes” in a “Link List”, and took the position of these. I added values to the position and provided this to a copy of the Tracer (made editable, intermediate points - none). The Iteration does all the work for each point. (Perhaps chose a different vector value if you encounter weird foldings, e.g., 0;0;100)

I hope it works for you.

Scene file
https://www.amazon.com/clouddrive/share/Vi0MhZfyUDlyjoIadt5iN6NKfTRJn3BaUKnJKac0rs?ref_=cd_ph_share_link_copy

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Dr. Sassi V. Sassmannshausen Ph.D.
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Posted: 03 November 2016 04:12 PM   [ Ignore ]   [ # 2 ]  
Total Posts:  10
Joined  2016-10-27

Hey

This is fantastic! Thanks so much.

I’ve encountered a small issue that I failed to mention though…

I intend to have 8 or more of these tentacle’s all clambering over the object. I’ve tried duplicating the rigs and arranging them in a radial arrangement but it seems that the Xpresso is not being applied to them all as well as the first tentacle that you fixed. Is there a way to make sure I can have 8 of these tentacles each individually climbing without the banking issues? I’ve noticed more banking now that I’ve duplicated the tentacles (I adjusted the duplicated Xpresso accordingly too).

I’m wondering if I can just wack these into some kind of cloner to speed up the arrangement process too…

I linked an updated file for you to take a look a what I mean - https://drive.google.com/open?id=0Bw4AQ_iwgwBpcE1qUWNvSWlWWWM

Thanks for the insight so far!

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Posted: 03 November 2016 05:39 PM   [ Ignore ]   [ # 3 ]  
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You’re welcome, Hayden.

Your question about file [_01]:

The key is to use for each of the Tentacles the related cubes (“BONE_”) inside the “Link List” of the XPresso for that specific tentacle. As well to a new Spline for each new Rail. While creating a copy, the app doens’t know if that the cubes have to be the cubes copied from the “Bone” group. This needs to be done manually.  I personally prefer Link Lists, as I can mage those. Alternative one could use other iteration methods to define the rail spline

The Rail that is produced must be the one for the specific Tentacle, otherwise it gets really weird.

I couldn’t see any change in the second file—compared with the first file. Even the name was the same. So, I can give you only a discussion here.

Alternative file [_02]:
https://www.amazon.com/clouddrive/share/pWnfujrQ2jpQYQfKUIFW5Odqd1ZOZFF0Ch09tUYLyv7?ref_=cd_ph_share_link_copy

The simplest way to create a rail via Tracer and be able to copy things without extra work is possible. One needs to add a “child” to each “bone-cube”. All of these child objects need to go in the right sequence (0- final) in a Tracer, as the first Tracer in the scene is set up.
Place all these child objects into a Selection Object to change them quickly, as you have used Selection Objects already. While all “Railnull” objects (child object) are active set the distance to the bone cube to produce a Rail with the Tracer.
This goes into the Spline wrap. Place all under a fresh Null (don’t use the Group Short cut!) including the Tracer and Tracer.r.
I tested it and it works here.

The twists in the tentacle are sometimes introduced by the “Connector” as they can twist. I made these cubes visible to have a clear view to that in the file.

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: 04 November 2016 08:21 AM   [ Ignore ]   [ # 4 ]  
Total Posts:  10
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Thanks so much for the latest version. Great to see it running without Xpresso! So interesting how such naturalistic motion is often driven by hidden chaotic variables.

Thanks again for helping

Hayden

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Posted: 04 November 2016 02:36 PM   [ Ignore ]   [ # 5 ]  
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You’re very welcome, Hayden.

My best wishes for your project.

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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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