Hi Sassi - thanks for the insight, have a good day.

Hello Sassi - I trust this message finds you well.

I have a scene file with an icosahedron and wish to clone tetrahedrons to each polygon face so that the tetrahedrons "fit" each face aligned, almost like the effect of stellating each face.

Can you please help me understand the steps to achieve this, so that each tetrahedron fits like the red arrow on the screenshot.

Hope that makes sense. Thanks, David
tetra-clone.c4d

Thanks once again for your help, have a good week.

Hello again Sassi,

Somewhat related to my last post, is there a way to have a selection tag on one object drive the selection tag on another object?

In the scene file, I explored the Correction deformer to create a loop selection around a simple Sweep object. I stored this selection then copied it to the Sweep object so that it could be extruded by the capsule.

Is there a way to link or drive the selection taken from the Correction deformer to the selection tag on the Sweep object?

https://www.dropbox.com/scl/fi/w4rfnwu0wbc43jetydjiy/drive-selection.c4d?rlkey=clkwx8rjjv6b9rv9jfm1290kq&dl=1

Thanks, David

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!

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...

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

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.

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

That is it! Yet again you make me see things from a different view. I was focussing so much on the Rotation settings of the Sweep, but you rotated the rectangle profile itself to achieve the result.

Thanks so much! Enjoy your weekend too.
-David

Thank you Sassi - yes, Möbius Band indeed

I see that you opened the spline and then tweaked the rotation curve graph. A couple of follow up questions:

1. Was the rotation curve graph eyeballed or did you use some other logic?
2. Now this is closed cleanly, I wish to rotate the whole band 360 degrees around its spline axis - like sliding the Sweep > Rotation > To or From Rotation values but without it breaking the join. I can send a video if this doesn't make sense.

Thanks,
David

Hello Dr Sassi,

In the attached scene you see a simple sweep along a spline. I have set the Sweep rotation to 180 degrees. As you can see the sweep does not close cleanly even though the faces are aligned. It looks as if Caps have been enabled which are being twisted and joined, but Caps are not enabled.

If you set the Sweep rotation to 360 degrees the sweep closes cleanly - I am trying to achieve the same clean joined look but with just 180 degrees rotation, if that is possible?

sweep-rotation.c4d

Thank you for any insight.
-David

@Dr-Sassi - many thanks for the forensics and highlighting the principles of splines.

My goal was create a "clean" closed spline to then sweep, in which the sweep would then be clean based on the spline, avoiding any breaks or odd rotations of the sweep.

I added the spline from the scene to the volume builder and having fun with it there to create the geometry. Although I was originally wanting a squarer look by sweeping a rectangle around the spline.

Best regards,
David

Hello Dr Sassi, I hope you have had a good week.

In the attached scene file I have created an "Edge to Spline" from the hidden geometry (included for your reference if you need to see the source edge).

On the spline, when clicking the "close spline" checkbox I see it creates additional splines indicating that the spline is not optimal. I have spent some time Optimising and Welding but I cannot seem to get a clean, closed spline with evenly spaced points.

I notice that when performing a rectangular selection around the points at the vertex, it shows 3 points but no amount of Optimising or Welding can reduce this to a single point.

Any guidance is appreciated...thanks, David

close-spline.c4d

Thanks for your time explaining once again.

Some nostalgia - I remember one of my first posts in the old forum was asking how to stellate a platonic to create a star shape. You recorded insetting each polygon until the points were just touching and then optimised to weld together all the points. But now, the simple but brilliant "poke polygons" takes care of this in a click...

Thank you Dr. Sassi, I will study the file. I noticed in the first file you prepared, you parented the platonic to a Null, and assigned the Align to Spline to the Null. But how did you arrive at the subsequent R.H/R.P/R.B values of the platonic which completed the orientation?

Hello, yes that's it, thanks for your help.

Just one further question. I want to spin (bank) the icosahedron as it travels along the spline. Would you create a guide and snap the guide to the top and bottom vertex. Then, after enabling Axis Modification, how can you align the axis to the guide so that the banking sits at 90 degress to the direction of travel? (I hope makes sense)....

Kind regards, David

Hello Dr Sassi,

I hope you are doing well, you may remember me from the old forum

Can you please help me to align an icosahedron to a helix so that when the position is animated, the icosahedron passes through its vertex along the helix.

I have played with the Align to Spline and the tangential setting, but this does not match what I want. It must involve setting the orientation first before aligning to the spline.

An eyeballed example image is attached. Any help is appreciated.

Thanks,
David