Splines are ..confusing

So I don’t get splines. I’ve used them for years but in shapr they just don’t work as I expect.

How can I add points that keep the curve flow?. As soon as I stop drawing I’m screwed the next point will be hard and no matter what won’t continue the flow.

Also I get always these weird spline arcs that are just bizarre they don’t make sense and don’t follow the logic. Look at image - tried to paste video but too big. At some point the curve is messed up and I can’t straighten it… it just won’t work. So shapr seems to do splines different than all other apps, I can under stand those apps but shapr has got to be different. I can never get them working ever lol . Usually I have to do hard angles and round them in geo, because they fail every single time… any clue how these are different then all other apps.

The spline gets all messed up and there are kinks in the spline… I have to delete and try again and generally it takes me many attempts to get it working. Usually it just won’t work as the kinks in the spline prevent it. So I have to do the splines in illustrator then import them in.

Shapr’s spline tool is pretty lackluster. I used vector editing extensively. Shapr’s implementation of it is pretty rudimentary.

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What would you like to see improved?

Adding points, cusping, point reduction would be fantastic. Symmetrical control/ smoothing at each point. Convert a line to spline, add points to it.


Been a while since I have really played with it. Had to go back to working. Will revisit it. Auto point reduction would be very useful when importing some drawings.

as you know we have two types of spline commands, one as “Fit Spline” and the other as “Control Spline”.
in my windows version, it’s possible to add a point at any arbitrary point on my spline just when I have drawn a “Fit spline”. To do that after drawing a fit spline, you need to activate the Spline command (either control or fit spline) and move the mouse cursor to your arbitrary point on your spline then left-click and hold that for a second to add a point there.

I hope that will be useful

  • There should be better control over the creation of splines - and on the editing of already created splines

  • Bezier splines should be default

  • Analysing tools for splines - and all other geometry as well (degree, point count, point weight)

  • Change degree

  • Delete knot

  • Convert to bezier

These are just random points - in no particular order - that came to mind. Bezier splines and surfaces (when/if we get surface tools) really are essential for product design - as are G2 and G3 blends. Without these tools it’s very difficult make smooth surface patches (and eventually solids) or to be really serious about product design (apart from ‘simple’ mechanical design).

Shapr is a great tool, that could be so much more… In my humble opinion Shapr right now is to heavily geared towards mechanical design (which is probably to be expected as you are using the Parasolid kernel).

Personally I’d like the Shapr team to also start focusing on free form surfacing (you have the manpower already) in addition to tools that are obviously made for mechanical design - otherwise you’re concentrating your efforts on only half of the product design field. That might of course be a conscious decision… Only Istvan knows.

That was a bit of topic also. Sorry about that. However… I still have high hopes for the future of Shapr.



Very nice G2 blends are coming soon.


Yes, I know - and that’s great! Care to comment on my other points…? :wink: I’d be especially interested in the direction Shapr will take in the future regarding the different areas of product design.


We are putting a lot of effort into making Shapr3D great for product design. The guided loft feature was one of the first steps. Have you tried it?


Yes, I’ve tried it. It’s a good first step. Waiting patiently for the rest of the free form surfacing tools in my list :wink:


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Here is an example of what I get every time.

The way the points + tangent bars are set up. It shouldn’t create a kink in the spline, nothing in the center should create that effect.

-also say people posting about adding/deleting points, how do you do that?
-How do I connect a straight line + a curve together and smooth the edge line to smooth line?. I generally have to delete and do it all via curve tool. The two don’t combine.

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I flattened it out like I would in illustrator - the center again is completely twisted. No what what I try I can’t fix this issue. I must do my splines in illustrator and import them in. They just get all distorted in Shapr3D :frowning:

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Here I tried to create a simple s-curve with sharper corners. Control I can achieve this with a lot of points. Fit it’s impossible, it just appears to be broken. Unless the spline logic is different than all other vector software- usually they shouldn’t perform this way.

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Did a quick illustrator test, easy to make flat - the shapr 3d one always has a weird distortion in the center.


In Illustrator these curves are piecewise Bezier curves, while in Shapr3D they are interpolated splines, that’s why they are different. You can achieve something similar by creating the curves with control points instead of fit points, and you can create multiple sections of the splines like this.

If you create each segment with 4 control points, and add a tangent constraint between the curves, you’ll achieve something very similar:


Thankyou @Istvan :). That makes more sense. I’ll give that a shot👍

I find this very confusing as well. Piecewise bezier feels like a standard, but I might be wrong. Control points like attached image should generate a straight line IMO, otherwise it feels more like luck when drawing something.

Perhaps more patience may be useful you understand well the “ language “ of 3D tool imaging and vector design As does Islov I imagine islov, however is Learning fluently now another language in developing apps and all that is involved. I can’t imagine how many messages a day he gets from the same people over and over him what he needs to do and how to do it. However he’s done so far quite well I’m certain will get around to doing much much more with these two perhaps one day your intern office will be in the palm of your hand around all will be well however we all must be patient this is a new frontier

This right here is why I use a 3rd party program for complex Bezier drawings then export/import DFX.

To achieve the illustrator version you might try lines + arcs and. The tangent constraint might help.

Shapr lacks 2 things in Bezier: Cusp and convert (from arc) to line. 2 very important necessary things used in vector art.

I’ll be complaining about this until they fix it!

I did a lot of technical vector drawing using Corel Draw for over16+ years. Vector tools done right.

Illustrator not as good for technical drawing. Illustrator more artist centric.