arrowhead plugin problem

[denzjos]

With the decorate / Arrow Heads Ofnuts plugin I've tried to draw arrowheads on both ends of a circle segment. It's a segment from a circle I've cut with the Tools / Cropping and slicing / Slice path by lines. The upper arrowhead is ok but the lower arrowhead is not wel oriented. Any suggestions to solve this problem? Thanks in advance. 
PS : The drawing in attachment is a detail of a bigger drawing, so zoom in to see the problem.


  arrowhead nok.xcf (Size: 9.55 KB / Downloads: 340)

[carmen]

The problem seems to be a duplicated lower anchor. Path summary (ofn_path_edits) gives:

Code:

Path "anchor arrow" [1]:
(84.3, 58.3) <- 3 : 27.4 : OPN -> (85.5, 33.7)

and, after Ctrl+Shift+click on bottom anchor:

Code:

Path "anchor arrow" [1]:
(84.3, 58.3) <- 2 : 27.4 : OPN -> (85.5, 33.7)

Then, arrow heads as expected (not bothering to attach--I am lazy).
By the way, my first trial didn't reproduce your arrow heads, giving instead a 'float division by zero' error message?? Different operating system, different Gimp version??

[denzjos]

thank you carmen for the reply. Sorry but I can't understand what you mean with the code to solve the problem. I used the plugin before for the same arrows (arrowhead on both ends) on the same drawing and there was no problem. Now, if I launch the script I get the same error. But as you mentioned, there was probably a duplicated anchor. What I did to solve the problem,  erased the arc (path), I made a new path and launched the script again. Now there was no problem, also no error, so solved (something messed up in the drawing ?) . Thanks for the tip. By the way, I'm using gimp 2.10.22 on windows 10.

[carmen]

Sorry for being unclear. If you have ofn_path_edits installed, on right click on the path in your attachment, you can choose 'Path Summary', which shows:

Code:

Path "anchor arrow" [1]:
(84.3, 58.3) <- 3 : 27.4 : OPN -> (85.5, 33.7)

Then, looking in the documentation (or in the 'Guide to Ofnuts Paths'   ) you see that the 3 after <- means that there are 3 anchors in the path--one too many. As there appear only 2 in sight, one must be duplicated, and as the trouble was in the bottom arrowhead, that anchor is the most likely suspect. Ctrl+Shift+clik on an anchor with the path tool deletes that anchor, and as there are still 2 anchors in sight and the path shows no visible changes, the anchor was duplicated indeed. For good measure, you can run Path Summary again: 

Code:

Path "anchor arrow" [1]:
(84.3, 58.3) <- 2 : 27.4 : OPN -> (85.5, 33.7)

Now, 2 instead of 3: q.e.d. A run of Paths Arrowheads gives further proof, if needed:   
I hope to have made my previous meaning clear, now.
Misquoting Alice (or rather, the pedantic Red Queen) the moral of this is: no need to mess the previous work--just use the tools. 
I still wonder how you got those wrong arrow-heads: our settings seem identical. Maybe a small edit to the path before saving...

[rich2005]

Quote: The upper arrowhead is ok but the lower arrowhead is not wel oriented. Any suggestions to solve this problem?

I am sure Ofnuts will give a correct explanation but you do not have a suitable tangent on the lower control point.

I got one by continuing the path, then deleting the new control point. bound to be a better way.

this is what I got. https://i.imgur.com/XojxOJ0.mp4

[Ofnuts]

(12-31-2020, 03:10 PM)carmen Wrote: The problem seems to be a duplicated lower anchor. Path summary (ofn_path_edits) gives:

Code:

Path "anchor arrow" [1]:
(84.3, 58.3) <- 3 : 27.4 : OPN -> (85.5, 33.7)

and, after Ctrl+Shift+click on bottom anchor:

Code:

Path "anchor arrow" [1]:
(84.3, 58.3) <- 2 : 27.4 : OPN -> (85.5, 33.7)

Then, arrow heads as expected (not bothering to attach--I am lazy).
By the way, my first trial didn't reproduce your arrow heads, giving instead a 'float division by zero' error message?? Different operating system, different Gimp version??

Exactly. With the duplicate anchor, the plugin is possibly trying to divide something by the difference between two identical coordinates, hence the division by zero.

[denzjos]

Carmen, rich, ofnuts, thanks for the clear and complete information. When I tested with a new circle segment , I also had a problem with the slicing script (to slice a circle path), slicing the segment with a line give the wrong sliced position, slicing with a guide was no problem. I have to search it out (maybe post follows concerning this issue follows)

[Ottia Tuota]

(01-01-2021, 08:21 AM)denzjos Wrote: Carmen, rich, ofnuts, thanks for the clear and complete information. When I tested with a new circle segment , I also had a problem with the slicing script (to slice a circle path), slicing the segment with a line give the wrong sliced position, slicing with a guide was no problem. I have to search it out (maybe post follows concerning this issue follows)

Please tell if the problem persists. I just uploaded a new version 0.3 with a small bug fix. But by what you say, you may have found some different bug.

[denzjos]

@Ottia Tuota : No problem with the slice plugin. I've tried to reconstruct the problem. Because I had a few paths on my drawing I was working on, I must have pointed in the script menu to the circle instead of chosing the line (path) when I used 'slice path by lines'. Then the result is not ok and that is normal because I pointed to the wrong path in the script menu. Anyway, fine script !

[Ottia Tuota]

Good. Very easy to do that mistake. Happens frequently to me too.