Expand curve with pen shape for calligraphy

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Alatius
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Joined: Fri May 31, 2019 12:19 am

Expand curve with pen shape for calligraphy

Postby Alatius » Fri May 31, 2019 12:29 am

I am in search of a feature that would make it easy to draw nice calligraphic curves. Basically, I would like to be able to edit Bezier curves and then generate or, ideally, see in real time an expanded outline around the curve, based on a pre-defined "pen shape", for example an oval. Consider this illustration:
Image
I want to draw the inner skeleton curves (dark red), and expand them with the grey oval shape to generate the black outline.

Is there any way to do this? I expected to find a "path effect" to do this, but couldn't find any. Am I overlooking something?

Is there some other open source vector editor with this capability, that you can recommend?

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brynn
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Re: Expand curve with pen shape for calligraphy

Postby brynn » Fri May 31, 2019 6:01 am

Inkscape has a Calligraphy tool. It doesn't work exactly how you describe. Unless you use a graphics pen and tablet, you have to use the mouse to draw the letters/characters with.

Some years ago, Lazur was working on something like this. Let's see if I can find the topic.... I can't seem to find it. Lazur changed user names at some point, and I don't remember the title. But I'm sure he'll reply when he sees this.

Lazur
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Re: Expand curve with pen shape for calligraphy

Postby Lazur » Fri May 31, 2019 8:36 am

Certainly.

It was a long and sort of unfinished project from a few years ago.

The result took a different turn, although there are traces of that journey.

This topic is the most related to the calligraphy problem.
"How to implement a custom pen shape along a stroke's core."

Gerrit Noordzij's "The stroke" was mentioned by the typophile community for starting.
Here is a short part of it.


To sum it up, there is no way to do so from the box.
The "computing solution" would be by sampling key positions of the trace and draw a taper by some interpolation method.

However if the pen's trace was only translated along the core at a given angle, it has a shape easier to be described.
(With some exceptions.)

___
tl;dr:
The only way to achieve such a result automatically I know of is by using transformations. (Admittedly not as a general soluton as using a custom pen shape though.)


If setting transformations to be preserved you can basically scale/rotate/skew the stroke style and end up with a diagonal and elliptical cap if the stroke style is set to be rounded.

Then just draw with the Bézier tool with stroke only and no fills.

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druban
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Re: Expand curve with pen shape for calligraphy

Postby druban » Sat Jun 01, 2019 4:12 pm

usually this functionality is a feature of painting programs, not vector drawing; the GIMP for example can do this in a flash, but it won't be vector, although you can start with vector paths.
Your mind is what you think it is.


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