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Point modelling
Posted: 13 February 2020 12:57 PM   [ Ignore ]  
Total Posts:  98
Joined  2018-05-13

Hello Sassi,

I have modelling question for the below scene file. You will see the shape has a selection set for groups of 5 polygons that form a pentagon shape. I want to have the center point of each selection to be “lowered” so that it forms a flat plane like the blue polygon. I have created a set selection for all center points on the object.

I made the blue polygon by deleting the 5 polygons from one of the selections, then using the “close polygon hole” to create the flat polygon. But I lose the sub-divisions which I know can be created again by inner extrude. But I am wondering if there is a quicker or more elegant technique to model all set selections to replicate the blue polygon, but retain the subdivision.

For example, can the point set selection be scaled inwards, but how would you calculate the amount?

https://www.dropbox.com/s/6hez8rs1st2k3fp/point-modelling.c4d?dl=1

Thanks,
David

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Posted: 13 February 2020 06:10 PM   [ Ignore ]   [ # 1 ]  
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Hi David,

The most practical way would be, to have the middle points selected, while the surrounding points are considered flat and not selected.

Then use the Mesh> Move> Iron Tool (set to 100%).
Screen capture
https://www.amazon.com/clouddrive/share/P7FD53gO2q0ZgjlpYMa05zJU8JHQSAqPndzpeUDi94B
and done.

====

The quick version would be to select the middle points and use the scale tool to scale them all towards the center until they are flat. Not precise, but fast.

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: 13 February 2020 10:37 PM   [ Ignore ]   [ # 2 ]  
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David,

As requested, the math option. This would be based on a formula.

The formula needs to be “($1*cos((asin(($2/2)/$1)*2)))/100”. The hundred here is the percent value to multiply the size of all points, as the request was for around the sphere selection.
I assume that the sphere is on World Coordinates 0, 0, 0. If it needs to be available to all sizes of spheres, this requires an update. If the sphere needs to be anywhere in space, other than zero, another edited is needed. But as usual, I try to keep it as simple as possible.

The formula evaluates the angle between the two points (mid and outside), and from there how one distance should be smaller. In this case of course the middle one.

Screencapture and project-file
https://www.amazon.com/clouddrive/share/7IWRP5G6QBTQoXTxI080qURmtFyf0zRxPPUwDHaYdVs

I hope that it is fast and straightforward to use. I found that it has a precision with an 0.02 percent error (2/100 of one percent, or 2/10,000) . I assume that it is based on rounding. No idea to get this down to absolute zero. wink

It is based on the file I got, to have a selection going around the spheres

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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Posted: 13 February 2020 11:45 PM   [ Ignore ]   [ # 3 ]  
Total Posts:  98
Joined  2018-05-13

Hello Sassi,

Well that last tip of the Iron tool was exactly what I was looking for - practical and quick. And thanks for sharing the other options to achieve this including an impressive display of math again.

FYI - I think your download link has “and” appended in the URL, you may wish to correct.

Have a good weekend, David

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Posted: 14 February 2020 03:11 AM   [ Ignore ]   [ # 4 ]  
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Hi David,

Thanks for the feedback and the tip with the link-word merge. Yes, that was not on purpose.

When I see a question about math/formula, I’m obviously too excited. Yes, the Iron tool is the way to go.

Have a great weekend, as well.

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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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