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I am back with a new challenge. I am hoping to draw a helical ribbon and arros with 3d bends and twists. I am in inkscape, and I do not beleive there is a ready made tool for this sort of thing. I am tempted to try and do this in blender but I will wait for the gurus on this site to help. An example image is attached. What I hope to avoid is having to use shading and gradients to get that effect as I lack the artistic talent to execute something that technical.

Thanks in advance.

example protein structure

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I think a certain amount of manual drawing, and messing with nodes is unavoidable, and gradients would need to be used. If you don't want to do all that, then Blender might be more feasible.

The following method results in a kind of pseudo 3d helix, however it doesn't address the thickness of the ribbon, and that would require additional manual work. Here in particular I think Blender might be more appropriate.

  1. Use the Calligraphy tool to make the ribbon shape, with a 90 degree angle, with fixation set to 100, mass set to about half way to smooth it, with a stroke and no fill

  2. Use Break Apart at Selected Nodes on some of the line segments, then Break Apart, and delete the lines you don't need

  3. Apply a bucket fill to the shapes, send the fills to the bottom under the strokes, and then change the fills to a gradient.

enter image description here

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  • That looks really nice, I may explore using blender I have a really hard time working with nodes in inkscape. – TheCodeNovice Apr 4 '18 at 15:30
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    @TheCodeNovice Blender has nodes too so be prepared for that. – LateralTerminal Apr 6 '18 at 14:08
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Unfortunately the one click solution hasn't still been found, but here's one quite usual. Node editing is kept minimal:

enter image description here

  1. draw a rectangle - stroke only, no fill, arbitary color

  2. fit a cosine curve, angle from 0 to 180 degrees into the rectangle. It's a plausible approximate of the seen serpentine spiral curve. Select the rectangle, apply Extensions > Render > Parametric curve, see the details in the dialog. It's only three node approximation, but surely accurate enough for illustrations.

  3. Draw with the pen a horizontal line (here red), duplicate it and the cosine curve. Set in the info panel "horizontal and vertical only"=ON for easy drawing.

  4. Have snap to the nodes ON, place the pieces to make the shape of a half ring of the serpentine

  5. Select all. Using the node tool select all nodes and in the info panel click "join selected nodes". You get one closed shape.

You can make multiple copies, flip half of them vertically, remove strokes, insert fill colors and place the shapes to make a horizontal serpentine. It can be bended along a curve.

enter image description here

  1. A flipped copy is made. Strokes are removed and fill colors are inserted.

  2. Several duplicates are made. All blue shapes are raised to top. The shapes are placed manually. They snap exactly with snap to nodes =ON.

  3. The same as 7, but opposite vertical gradient fills are applied. This is the right place to learn exactly how to insert and edit gradients.

  4. The shape (=8) is bended along a path. Unfortunately the gradients are lost.

    • group the shapes
    • draw a curve
    • lower the curve to bottom
    • select the group and the curve
    • apply Extensions > Generate from Path > Pattern along Path, see the dialog for details

The curved serpentine is a group of shapes. Ungroup them. Recolor every shape with the gradient edit tool. Actually only one click+one drag is needed per one shape:

enter image description here

This resembles what you can get out of a 3D program with simplest possible light and material settings. There's no glossy reflections nor sharp shadows.

Simple low cost 3D software can easily make more complex lights and shadows. The shape itself is a short line which is sweeped along a helix. The result is bended along a curve:

enter image description here

That was not properly rendered because the used program hasn't such capablity, only simple shading with a selection of highlight and shadow rules. Some gloss is allowed.

Precision rendering lifts the plausibility up. This is the same model rendered in an introductory version of Keyshot. If you can use Blender, there's no need to accept anything less:

enter image description here

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  • Nice I upvoted. Is #8 some kind of gradient? – LateralTerminal Apr 6 '18 at 14:07

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