Circumscribed tangent circles.

[Krikor]

Is there a way to get that kind of circle arrangement with Gimp?
   
For example, knowing the radius, or the diameter and the number of desired circles, how to proceed to create this formation without the circles overlapping (only touching each other tangentially) forming a circle of circles.

I got something very close to this using (Ottia Tuota) Markku Koppinen's replicate path along circle plugin, but the adjustment between the source path and base path was on a trial and error basis.

In the image above, Inkscape was used.

I tried with the ofn-path-to-shape plugin, but I wasn't able to get anything close.

Any suggestion?

Thx!

PS.: Sorry about the title, but that's what I could come up with.

[PixLab]

EDIT: I did edit with a better solution, see from "Edit" below near the end, I left the Symmetry option as it can be preferred by some one people

Still trial and error (I did just 1 error, though) but it's extremely fast as just 1 Ctrl+Z, then just move the selection once and that was good

Symmetry Painting ➤ Mode Mandala ➤ Number of point = 5 (will draw 5 circles at once around the center crossing guides automatically made by the Symmetry Painting
Now use the ellipse select tool, or your path (just one path in circle),
Then put one side against that vertical guide. (important to simplify trial/error)
Then now the usual thing Edit > Stroke Path/Selection WITH a brush (that's very important as Symmetry Painting works only with everything brushes/eraser things)

   

after adjusting the selection by moving it down along the vertical guide with the move tool ➤ because the circles were a bit too far from each others on my first try

   

Very important after you're happy do not forget to put the Symmetry Painting mode None or all your brushes will continue to symmetry paint  



EDIT: even better Recursive transform tool ➤ No trial and error because adjustment are live on the canvas  

Have your 1 circle made then go to Layer ➤ Crop to content (that's important)
Once it's done go to Filters ➤ Map ➤ Recursive transform, a window opens put  Iterations 4 (it will add 4 more circles on top of the one you already have),
Controls are on the canvas, move that cross center on a corner first (slightly outside)
Then rotate the recursive transform tool by moving your mouse outside the control square like the normal Rotate tool, adjust that cross center you've moved outside then rotate slightly to update what you see.
You can even "cheat" a bit by increasing/decreasing the circles sizes (live on screen) by using the big square control the same way as the "Unified transform" tool, using same key modifier (Shift) to keep the ratio (no deformation)

   

[rich2005]

You can calculate this but a pita, so using Gimp and 'eyeballing'

I use an old script, duplicate and rotate a path. It has been posted before but I will post again. Really you do need a symmetrical image for this, makes life that much easier.

First some spokes from the center to the large circle. Twice the number of required small circles. Make a path, apply the script.

   

The only thing certain from this, is the small circle(s) touch in two places. Make your elliptical selection fit, make it into a path.

Same script, but for 9 repetitions of the small circle.

   

Quote:PS.: Sorry about the title, but that's what I could come up with.

Since I am feeling not so wonderful today, how about Contiguous circles on PCD (PCD = periodic centers diameter)

[Ofnuts]

(08-27-2022, 10:25 PM)Krikor Wrote: I tried with the ofn-path-to-shape plugin, but I wasn't able to get anything close.

Principle: your circles are centered on the vertices of a pentagon, and their radius is one half of the side of such a pentagon. So:

• Create a pentagon (several ways in OPTS)
  
• Edit > Disjoin strokes (ofn-path-edits)
  
• Transform Segments > Resize strokes : 0-50 (o divide by two)
  
• On Segments > Circles,   use "Radius"
  

   

More later, nap time 

[PixLab]

Oh yeah, I forgot, so easy with a pentagon as reference (thanks Ofnuts) and symmetry painting

1 minute video https://imgur.com/a/REYNB2o

[Krikor]

Fantastic!

PixLab, it's been a long time since I've played with these filters (Symmetry Painting and Recursive transform), although in the trial and error category, both are easy to perform.

"You can even "cheat" a bit by increasing/decreasing the circles sizes (live on screen) by using the big square control the same way as the "Unified transform" tool, using the same key modifier (Shift) to keep the ratio ( in deformation)"

Here, trying this "cheat" didn't work, as the circles behave individually as I drag the square to scale the circles, each with a different radius.
But it is still possible to complete this resizing later using the scale tool.

rich2005, this technique is amazing!! It is possible to define the radius of the small circles even before generating the copies, and in the end everything fits perfectly!

I can't edit the title of this thread anymore (I even tried), but I agree that "Contiguous circles on PCD (PCD = periodic centers diameter)" is besides better, a more elegant title.

Ofnuts, based on my previous experience following the tip from rich2005, where I placed a pentagon inscribed in the circle (it just happened as I was digging into how to use the plugin), I couldn't understand the 'Principle': "your circles are centered on the vertices of a pentagon, and their radius is one half of the side of such a pentagon."

But then I decided to just follow the instructions and voilà!

I've been struggling with this task for a few days now...
   

Thank you all!!!

---

(08-28-2022, 04:21 PM)PixLab Wrote: Oh yeah, I forgot, so easy with a pentagon as reference (thanks Ofnuts) and symmetry painting

1 minute video https://imgur.com/a/REYNB2o

Oh yeah, so easy after you guys showed how it's done. 

The interesting thing is that with a compass and a ruler I knew how to achieve this result after a few strokes and the creation of a pentagram.
And just like Ofnuts had said, "your circles are centered on the vertices of a pentagon"
   

PixLab, this technique you posted on the link is even easier than the first via Symmety Painting you suggested.
   
Thx!

[denzjos]

@Ofnuts, nice approach.
   

[PixLab]

Claude Lion (cli345) made a G'MIC filter about it (Rendering > Tangential Circles) > http://gimpchat.com/viewtopic.php?f=28&t...20#p276726
You can put many more circle inside if you wish  

   

[Krikor]

PixLab,

This filter seems to make it possible to create the inner circles as a function of the larger circle, something like the solution given by rich2005, and that was exactly what I was looking forward to.

Unfortunately my G'MIC is version 2.9.9 (572 filters available), that's what came with my version of Samj's portable.

I only update G'MIC when I update my version of Samj's portable.

I still have Samj's portable version 2.10.32 (which turned out to be problematic and unusable) on a usb flash drive left in the office.

In this flash drive the G'MIC version is precisely 3.1.5.

Possibly, next Monday or Tuesday, I'll have access to that flash drive and maybe I'll be able to take a good look at this filter.

I haven't accessed Gimp Chat for quite a few days now, but now it's 4:36 4:43 am and I still haven't slept, but I'll check back later on that link you posted.

Thank you so much for the great news!

[rich2005]

Quote:..snip...Unfortunately my G'MIC is version 2.9.9 (572 filters available), that's what came with my version of Samj's portable...snip..

Assuming maybe a samj portable Gimp 2.10.28 (gmic 2.9.9 ) It is possible update the gmic plugin.

Get the Windows plugin gmic 3.1.6 zip and unzip next to your portable Gimp

Too many screen shots - all-in-one here: https://i.imgur.com/F116L6j.jpg

1. In the Preferences plug-ins folder -> gmic_gimp_qt folder disable gmic_gimp_qt.exe by renaming

2. Start up portable Gimp and add the path to the 3.1.6 gmic_gimp_qt folder.

3. The user.gmic file goes in the portable Gimp GMIC_Filters folder

4. A portable Gimp restart and you should have an updated gmic and if you do a search for circle, the Tangential Circles (pre-release) menu entry.

attached user.gmic (remember to unzip it)