Drawing curved lines

Does anyone know how to draw a smooth curved line, using only native Sketchup tools?

The Freehand tool in 2022 does smooth lines. Would that do?

Just checking — SketchUp is a surface modeler. All entities are comprised of straight lines. You can make a curve appear smoother by increasing the number of facets or straight edges in the curve, but it will always be a collection of straight lines. You may already know this but just in case.

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You can also change the number of segments in an Arc. See the difference between my default of 12 segments:

And after changing to 50:

No you cannot. Your element is an arc. With an arc, you can.

I’m obviously using the two terms interchangeably but have updated the post to show ‘Arc’.

The Freehand tool produces a “curve”. It might be a good feature request to be able to change its segment count.


I am familiar with these approaches. I have discovered an interesting method of drawing curved lines that appear remarkably smooth. The line is composed of segments, but you can’t see them as you can with circles and arcs. The interesting thing is that there is no need to increase the number of segments. Here is an example. When I have some more time, I will try to record a video of what I’m doing.

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After drawing a Freehand curve you can alter its number of segments with the Ctrl and Alt keys. But, you can only go up to the number there were, the feature is mainly so you can optimize the curve into less segments. We have talked about making it increase the number of segments, but didn’t yet get around to that idea.

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One can also draw some guides:

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Please, share your method??

This video clip shows how I do it. The reality is that it is an arc, and consists of straight line segments. But it’s the best way I can create the illusion of an actual curved line that doesn’t appear to consist of segments. In fact, it is the segment of a circle. That leads to the question of why SU does not have a Bezier curve tool as one of it’s nat

ive tools?

Yes, of course an arc drawn with such a large radius and narrow swept angle will look rather smooth because there’s little angular change from one segment to the next. If you wanted a larger swept angle you would need to increase the number of segments to get the same result.

So where do you stand on the absence of Bezier curve tools in native SU?

“Bezier curves are not only rampant in the Adobe suite (in creative apps like Premiere, Photoshop, and After Effects), but you’ll find them in just about any type of creative app.”, but not in SU!

CAD applications , or any digital tool used for design, also uses Bezier curves for many things.” Doesn’t Trimble consider SU a CAD program?

Who, me? It really hasn’t been a problem for me. I have used Fredo6’s BZ_Spline and FredoSpline and they work fine. So does the SU Bezier tool which has been around since 2004 and freely available to anyone who needs it. I’ve been a fan of the SketchUp Team’s idea of providing a basic but powerful set of tools and let users add the tools they need for the kind modeling they are needing. I know long-time SketchUp users who do amazing modeling and have never needed to use Bezier curves.

Of course I’ve only been using SketchUp since 2003 so maybe when I have had more time with it…

No. It’s a 3D modeling application.

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What is the difference? My understanding is that SU is surface modeling/vector graphics application. That spells CAD in my book. Do I need to correct my spelling?

Frankly, who cares what something is called, but I would say that SketchUp is not Computer Aided Drafting…


I think we can agree that computer software terminology is nothing more than technical semantics, and as such. somewhat arbitrary. But, the work done in SU is 3D design. In regards to drafting, I recently demonstrated to a relative who brought me his drawings of a gate proposal. I showed him how dramatically faster it was to do his drawings in SU. Then I took the 2D drafting I had done, and made it 3D. I proceeded to construct his gate in full 3D in a matter of minutes. That’s flat out CAD to me. I use to do the same thing in AutoCAD, but nowhere near as quickly, From the standpoint of software definition, I see SU and AutoCAD both as CAD software. SU is a surface modeler, and AutoCAD is a sold modeler.

This looks to me like you are just drawing an arc. I don’t see how that’s any different than any other arc, or circle or curve. Bigger the radius, the softer the departure angle, or just increase the number of sides.

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Exactly, but it’s a different method of creating the curve than I had been used to doing. From a drawing standpoint, it makes things much easier in certain situations.