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Want to draw fake shapes from multiple stroke lines like the image below. As far as I know, it can be done by manually dragging the lines, but it's a hard job on complex shapes, and it's slow and not accurate. Wonder if there is a plugin, extension or path effect can do this in a faster way?

Illustrator or Inkscape can be.

enter image description here

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  • So, in essence manual shape generation happens in many cases not by pulling control points, but by cutting existing shapes. In this case you just have a buch of circles that you cut with another circle.
    – joojaa
    Commented Aug 22, 2022 at 8:02
  • Or ovals and cirlce in tihis case
    – joojaa
    Commented Aug 22, 2022 at 8:23
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    This is discussed several times earlier. Illustrator has very limited and Inkscape has none tools to define wanted 3D forms and put patterns on them. See this . It contains a link to a tool made by a programmer graphicdesign.stackexchange.com/questions/142669/… This is quite the same graphicdesign.stackexchange.com/questions/122443/… This wants a wireframe graphicdesign.stackexchange.com/questions/152274/…. Your example is tricky - it looks 3D from the top.
    – user82991
    Commented Aug 22, 2022 at 8:51
  • @joojaa got it, in this case it's more accurate to cut shape with multiple circles than to pull control points. Still wondering if there is an automatic way to do this?
    – jdleung
    Commented Aug 22, 2022 at 9:04
  • @user287001 I had tried the script tool in the referred link before asking question, it's an easy way to achieve the effect, but as you said the example is tricky, the script tool didn't give me a 3D round top, but a flat top, and its angle looks like 45 degrees looking up, but not overlooking from top vertically.
    – jdleung
    Commented Aug 22, 2022 at 9:30

1 Answer 1

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Some simple 3D forms can be made by extruding or revolving 2D curves in Illustrator. Then one can map patterns on the generated surfaces, but there's very little control on how Illustrator wants to place them. Inkscape has not even this.

You can create 3D-looking patterns by blending in Illustrator. Inkscape has "Interpolate" which is quite the same. Then there's the envelope distortion in Illustrator and a drastically limited version of it in Inkscape. With them you can bend clouds of lines or curves. The result may resemble something 3D surface if you are lucky and in addition you have a goal which happens to be possible to be made in that way.

But if you have an already decided "I want it" 3D form which is not an extrusion or revolved surface you generally have no other possibility to present it as a cloud of curves other than drawing every curve manually. Artists have done it hundreds of years, but developing the needed skills takes years (assuming the person has got in birth what the job takes).

3D programs are useful if the program allows and the user knows how to generate the wanted 3D surface. Your half-sphere is simple. Only to generate such line pattern which shows the 3D form also in the straight top view needs some thinking. One possibility is to split a solid with non-parallel planes and then to use the splitting borders as the image.

enter image description here

The image is just before the splitting. The solid is a half sphere on a plate.

After using the split body function and hiding the splitting planes the top view in wire frame rendering mode looks right - except there's no straight lines in the left and right and there's a circle which should be removed.

enter image description here

I took the curves into Illustrator, deleted the unwanted parts with the shape builder, inserted a couple of straight vertical lines and changed the stroke width:

enter image description here

The curved parts are pieces of ellipses. One who knows some elementary geometry could calculate the right ellipses and draw them in 2D from the numeric measures. A talented and well trained draughtsman may see the right ones without any math. But a 3D program gives them with very low effort, as shown above.

If you want to go to 3D software to make something substantially more complex than what's got by applying a 3D geometry creation primitive like extrude, revolve, sweep, loft, cut etc... you take a new challenge: It's far from trivial to learn to model something complex, say cartoon figures, realistic curved surface vehicles, animals, etc... Creating them from scratch needs same abilities as sculpting.

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  • I happened to try Fusion 360 weeks before, according to your suggestion and my understanding of Fusion 360 so far, I think this is a low effort way, even for other shapes. Thanks a lot.
    – jdleung
    Commented Aug 22, 2022 at 13:48
  • @jdleung You find easily Fusion 360 videos where one puts together say a free form lookalike model of a Ferrari or Mustang P-51. The shown movements (there are plenty of them) are not complex, knowing the needed movements is complex. Making something which resembles say a human face is what I call really complex. For ex this youtube.com/watch?v=P3DTCgGFBuo And there's no software usage problems, only the knowledge problem "what is the right form" and, of course, training to move one's hands accurately enough after one knows the right form.
    – user82991
    Commented Aug 22, 2022 at 15:10
  • Could you tell me which 3D software you're using? I created the object in Fusion 360, but under a free version, it doesn't allow to export it to vector format.
    – jdleung
    Commented Aug 23, 2022 at 8:21
  • It's DesignSpark Mechanical, a free version of CAD program SpaceClaim Engineer. There's also severe limitations (like usually, buy the real thing if you want more), but printing a wireframe view (+no hidden lines ) with Adobe PDF printer generates often a version which is usable in Illustrator. This was one such case. Try the "print wireframe as PDF" trick in Fusion 360. It's possible that there's also a forgotten hole.
    – user82991
    Commented Aug 23, 2022 at 8:34
  • It seems that the hole is fixed on Mac, I'll try it on Windows later. Thanks.
    – jdleung
    Commented Aug 24, 2022 at 6:12

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