Hatching Inconsistency

[Roger]

Hello I’ve been using the super nice hatching algorithm in Inkscape (thank you!). And I came upon an odd phenomenon where the spacing between lines will not be consistent depending on the angle. I ran into it several times and only recently tried to isolate it.

Please see the attached images and notice how only the angle changed:
https://ben.akrin.com/eggbot_hatching_bug_01.png
https://ben.akrin.com/eggbot_hatching_bug_02.png

I ran the same test on a new SVG with only a simple square shape, and it does not happen there. There is something to this file that produces this bug, I did run into it with several other files so please let me know if you need more examples.

Here in the file in question:
https://ben.akrin.com/grisou_head_only_3.svg

I hope it’s a quick fix, please let me know if I can do anything to help resolve it.

[Windell Oskay]

I can reproduce the issue. It appears to be something with the document setup, that Hatch Fill is not handling correctly.

It’s easiest to reproduce by using the “crosshatch” option, as the perpendicular hatches are at different spacing.

If I copy the graphics to a new Inkscape document, Hatch Fill works correctly. If I copy a working object into that document, Hatch Fill has the same issue here.

I’d suggest trying our recommended AI SVG export/import path and see if that resolves it; I’m frankly surprised that Hatch Fill works at all on this documument.

[Roger]

Windell, thank you for your idea to copy it into a new document. I isolated it down to 1 shape on 2 documents, the original (which exhibits the bug) and the new document (which does not), I went through every attributes until I found the culprit.

It turns out that the svg element needs to have a height and width defined.

How it interacts with the hatching working bizarrely at different angles is beyond me :).

Thank you again for the super nice hatching algorithm and your help here. I hope this finding ends up helping someone else.

Take care.

[Windell Oskay]

We do have a “Process Illustrator SVG” extension, as part of the AxiDraw Utilities, that does specify a recommended export process for the document that includes using the Artboard — which I think may be the part that sets the SVG size.

In any case, the Hatch Fill extension isn’t handling some special case of SVG dimensions or viewbox.

[Author]

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