Hey everyone, im back again at 3D modelling !
It's been a long time since I didn't touched MoI (since last v2 beta)

I just purchased my V2 upgrade, ready to do some MoI again.
Thanks again Michael for that awesome piece of software !

Just a little tought, Im sure you already heard of Inkscape (the free vector drawing app)
Inkscape got Spiro Curves (Cornu spirals) since V0.47 and it's an awesome tool !

There's more info on the original Spiro page -> http://levien.com/spiro/
And a little video showing the Spiro effect inside Inkscape -> http://www.youtube.com/watch?v=3OaLZuFZxdk

What I love about them is they allow you to draw perfect curves, with fewer control points !
It's more a 2D kind of tool, but since I also use MoI for 2D drawing and I know a lot of people do the same, it would be nice to hear from you if this kind of tool is potentialy code-able :)

I think it's good for logo design, landscape architecture and regular architecture, object design (freeform stuff) and of course jewelry and watch design...

Have a good day'

Oh and another fun fact about Spiro Curves for designers, it's G4 continuity all the way, but you can work in G3 and G2 also :) Try to do a G2 design using regular bezier curves aha :D

HI DesuDeus, yup I've looked into Spiro before, it's pretty cool!

One of the difficulties with it though is that it's not just "mostly for" 2D work, the whole mechanism actually only works for 2D planar curves, it's not something that can work on a curve that needs to bend around in 3D space. So that means it could not work just as a fully general replacement for curve interpolation, it would probably need to be a special mode or something like that.

Then the other problem is that the library itself seems to be abandoned by the author, I've contacted him about licensing it but he seems to be too busy with his new work at Google to be able to focus any attention on anything to do with the Spiro library.

And unfortunately the library that he has released is under a license that prohibits its use in commercial applications like MoI, the library is allowed to be used in Open Source applications only (like Inkscape for example).

So currently it does not look like it is possible to use it inside of MoI.

In the future I want to experiment with some kinds of energy-minimization for curvature distribution which may give a similar effect. The most interesting thing about Spiro curves to me is not just continuity but more about the nice and even distribution of curvature along the curve.

- Michael

Damn, it's sad he abandoned the project. One of my current boss is also going to Google in Switzerland at the end of this year :(
I think it's great, like you said, for the nice curves that this library can make. Too bad it's not licens-able for commercial.

But well, Spiro is not the only thing that can do nice curves...
Thanks for the reply :)

I don't know if it is the same source code but these curves look like Bezier curves in Blender. I'm pretty sure they are limited to 2d planar drawing then extruded or swept into the third dimension.


http://wiki.blender.org/index.php/Doc:Manual/Modeling/Curves

ch

Hi unclecharlie,

> I don't know if it is the same source code but these
> curves look like Bezier curves in Blender.

No, they're not really the same - if you look closely you should notice some differences between how Spiro curves work and how Bezier curves in Blender work. Specifically Spiro curves are controlled by a set of points on the curve and don't have those tangent handle things that the old-style Bezier curve editing has.

- Michael

The funny of SPiro shown on the escape video
is how is managed the control!
On an external rectangle curve :)

Hi Pilou,

> The funny of SPiro shown on the escape video
> is how is managed the control!
> On an external rectangle curve :)

You mean for controlling the width of the shape? I think that's a feature of Inkscape for applying a pattern to follow a curve, that part does not have any specific relation to Spiro, Spiro is used there for the centerline curve.

I hope to be able to have something similar to that pattern-applying stuff with some of the deformation tools that I want to work on for v3.

- Michael

< with some of the deformation tools that I want to work on for v3.
cool :)

Hi DesuDeus

thanks for the hint to Spiro Curves. Nice tutorial.
Could be a really nice improvement for upcomming releases.

A simple D with "spiro" and a star for "pattern along path"

Spiro curves are quite cool!

Mr.T

FYI:
You can do a "copy and paste" from Inkscape to Corel or Illustrator.

"Spiro Curves for MoI!!!!!"

Thanks for the tip BurrMan, I wouldn't have tough of trying this.

It also works in xara.

Marc

Great tip BurrMan, much appreciated! Works for me under OSX with an old copy of Canvas 9 too :-)

Regards
Stefan