Sweep rotation / loop selections

[FiveD]

Hello Sassi, I trust this post finds you well - its been a while

In the scene file (link below) you will see a trefoil spline swept with a rectangle called "Base". I have animated the sweep's rotation 90 degrees over 100 frames @25fps to create a loop. All good so far I hope...

Now hide the "Base" object and unhide the "Modified" object. Here you will see I had to make the Base object editable so I could create the loop selections as stored. But as you will know I have now lost the rotation animation which is what I want to maintain.

1. Is there an outcome possible to maintain the Sweep's rotation while creating and extruding a loop selection as shown?
2. Can loop selections be performed parametrically on a Sweep object? I've looked at capsules but cannot get it to work.

I have also played with the Spline Wrap using a profile of the extruded geometry but get some undesirable twisting issues during rotation.

https://www.dropbox.com/scl/fi/1rgt1hpwg5to4aqsy0voc/sweep-rotation-extruded.c4d?rlkey=4wt6ifx5hheq53704abkvkv03&dl=1

Thanks for any help.
-David

[FiveD]

To add to the above, I want to apply a material to the loop selection and a different material to the rest of the object. Thanks.

[Dr. Sassi]

Hi David,
I hope this post finds you well as well. Thank you.

Here is your file back:

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CV4_2024_drs_24_ANtp_01.c4d

I created a copy from it (Current State To Object)
Then, I selected four Polygon Loops and saved them in a selection tag.

This was then placed into an Extrude Capsule from the Asset Browser.
Anything else is in the file.
If you change the spline interpolation, the Selection must be updated.

I have set the duration to 0-99, as frame 100 will be the same as frame zero. 0-99 are 100 frames. With 25 fps, that is a good match.

Here is the Trifoil as Formula Spline; I assume you want it. If you need a directional spline (Rail), use 110 instead of 100.
CV4_2024_drs_24_MOtf_01.c4d

My best wishes

[FiveD]

Well that is the outcome I wanted - thank you. But I'm trying to wrap my head around how the selection tag of the four Polygon Loops that were taken from the Current State To Object object can then be applied to a different object's polygons? How does Cinema associate the selection tag taken from one to object to the polygons of the other object?

Kind regards,
David

[Dr. Sassi]

Thank you, David, for the reply.

At the moment, you are OK with the Sweep setup; use the Object Manager> Object> "Current State To Object" function to create an object for selection harvesting.
Select the parts that you like to have extruded, and create a Selection Tag. This Tag then goes into the Extrude Capsule (the one from the Asset Browser).

This is a particular selection; any change of the Sweep is useless.
In other words, you need to produce a new one. There is no procedural or simple way otherwise. Perhaps a polygon selection that uses the Spline as a field, but that is a somewhat less versatile option.

I hope I explained it enough; please let me know if not.

Enjoy your weekend

[FiveD]

Thank you Sassi. I understand the sequence of steps fine, your explanation is clear.

I didn't know that you could "harvest" a selection from one object, and then have the Extrude capsule use that selection which is then being applied to a completely different object, which in this case is the geometry being generated by the sweep function. I thought the selection tag would be "hard" wired back the original object (the current state to object) it was taken from...?

Something new I've learnt...

[Dr. Sassi]

Thank you for the feedback, David.

Yes, selections have been a bit more versatile for a while.
In some cases, fields can be beneficial for defining what you need.

Example
CV4_2024_drs_24_MOsf_01.c4d

Cheers

[FiveD]

I do follow Maxon's content on YouTube, Ask the Trainer and Quick Tips especially. Maybe Jonas Pilz could make a Quick Tip about harvesting selections and applying them to other objects? Maybe there is one and I have missed it...

Thanks again for your insight and help. Enjoy your weekend too!

[Dr. Sassi]

Hi David,

Here is a little clip showcasing a simple procedure to use a Polygon-based copy to create a selection and then copy this selection to the generated version; here is the Sweep.
https://stcineversityprod02.blob.core.windows.net/$web/Cineversity_Forum_Support/2024_Clips_DRS/20240224_Selection_Harvest.mp4

In that way, I have created the selection of materials for your project.
CV4_2024_drs_24_ANtp_11.c4d

You can send questions to ATT via email, so anyone on the show can prepare material for the question and produce more information, given the same time frame.

askthetrainer@maxon.net
Put in the Subject line QUESTION.

As a side note, perhaps explore these capsules
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More about
https://youtu.be/3DQKbJ2xWgo?feature=shared

Have a great Sunday