ofn-bend-path error / help?

[rich2005]

You seem to have it cracked, as far as polar coordinates concerned, however, new day and for others a little video, one way for that semi-arc.

There will be other ways, just experiment. Good practice, for using Gimps arithmetic abilities

2 minutes 20 secs https://youtu.be/O31-iqLmPn0

[rich2005]

A different approach, might come in useful. 
This using only paths and Ottia Tuota's Path Transforms plugin see: https://www.gimp-forum.net/Thread-Path-transformations

Using this:

   

The plugin dialogue: Path shaped by a bezier arc

   

Gives this:

   

Remember, that arc is a 2-node path, no use making from a circular selection.

[eepjr24]

(11-26-2020, 12:43 PM)rich2005 Wrote: A different approach, might come in useful. 
This using only paths and Ottia Tuota's Path Transforms plugin see: https://www.gimp-forum.net/Thread-Path-transformations

Using this:



The plugin dialogue: Path shaped by a bezier arc



Gives this:



Remember, that arc is a 2-node path, no use making from a circular selection.

Well, even with the polar arc, I cheated and just did a 2/3 path, flipped, merged and edited. So if you use a repeating pattern it could easily get you to the right result still, correct? And it seems to be relatively simple to do.

Thanks all on this forum for being so interactive. The ofn-bend-path did not turn out to be what I needed this time but now I know what it does along with the ofn-path-edits and ofn-dial-marks. Plus now I have a lot more knowledge of strokes, paths, polar coordinates, and another new sets of plug-ins in my toolbox. Nice to see such a community, hopefully I can contribute back at some point.

- Ernie

[Ottia Tuota]

Thanks for remembering my plugins, Rich. It seems that I have difficulties remembering myself what I have done. Must be the old age...

There is also the Exponential map among my transformation plugins. I made the following test path:

   

Then I called the Exponential map with the following inputs:

   

and I got the following:

   

The exponential map means the complex exponential map when the plane is viewed as the complex number plane. In its basic form it sends horizontal lines to circles, vertical lines to rays emanating from a common point, and all other straight lines to logarithmic spirals. In the example above you see two big circles, and a lot of small circle arcs and line segments.

To get the plugin, go to

http://kmarkku.arkku.net/Path_transforma...aster.html

Scroll to the bottom and press the Download button. Unzip the .zip file you get and put the .py file it contains in your Gimp's user plug-ins folder. Restart Gimp. You find the plugin in Gimp's menu by going to the Paths tab, right-clicking the path you wish to transform, and following Tools > Transformations > Exponential map.

Then you can go experimenting. You can start with the same inputs as in the picture above. BUT: The last input in the GUI is choosing the algorithm. I recommend that you do experiments by setting the algorithm to 4 (or 5 or 6). Only after you are satisfied with the result, set the algorithm to 0 and run the plugin again. Namely, with algorithm=0 the plugin is slow but gives the best result. With all other values the plugin is fast but the result may be unsatisfactory (weird even) and the resulting path will have a very large number of anchors.

I hope this helps. If you have problems with the plugin, please ask.

[Ottia Tuota]

And, for comparison, the plugin To polar coordinates (in the same package), with inputs

   

made from the same test path:

   

where I had to use also scaling and moving. But by using as the reference box a rectangular selection that was as wide as the test path but taller, I got:

   

So, some experimenting is needed.