More fancy curve testing WIP v8

Have been playing more with Steve’s testfancycurves in v8- they seem to have a nice application to 2d artwork as well…

I dusted off this old drawing and was playing with the look a bit with fancy curves. (expand image to see more clearly the detail of the lines)

to my eye it’s more interesting than just a drawing with a thicker silhouette applied which is what I had before-

ideally I’d love a combo of the two- with a thicker fancy silhouette…


This efforts is visually similar to the weight intent we do in hand sketching, except for one aspect, and probably the most important aspect: line weight in hand sketching is never random. It is also never related to a proportional length of the stroke. For example: these fancy lines seem to render variable thickness based on a 20% thin start + 60% thick middle + 20 % thin end of the stroke.

When I sketch I clench down and push the pen when I want to indicate a part’s outline or contour line (behind this line there’s some depth, or 3D airspace).

Until these lines are truly 3D, so such logic could be inherited from 3D information, the best, most immediate approach would be capturing pressure sensitivity, or some other key modifier to allow the user to input ‘clenching down’, where they mean it.

Right now it’s just gimmicky IMO.

I hope this helps,


Of course it’s gimmicky; that’s why it is a test command. I know Kyle is excited about this, but this is also why we typically don’t discuss test commands a whole lot. You’ll also notice there are a lot of other options in this test command that don’t have anything to do with tapering as I use this to test a bunch of different potential display features.

There isn’t any randomness here; the test command is a big global hammer that affects every curve in the scene with the same settings which is why you’ll never be able to get what you want just with the features that this command offers. There is a setting for a maximum taper thickness and a position along the curve to apply the maximum taper thickness that gets applied to all curves.

The next areas of work here would be to:

  • allow application of these settings to individual curves
  • figure out what would be needed to support vector output for print/svg/pdf
  • improve on the taper algorithm

yep, and as this is super early, this type of feedback is good. (although I’m way ahead of you already, and have tons of ideas for ways to control this stuff to get the “look” right :wink: I plan on lobbing ideas at Steve for uses and features on this until he blocks me on all forms of media.

Hi, I have been trying to use testfancycurves in the 8 WIP on my mac but it does not alter my lines to tapers. Is it meant to work on a mac yet?

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Hi Giusseppe -

In a quick test here on my Mac, that seems to be working as it should. Make sure to enable the Metal display pipeline with the TestMetal command.

thanks Wim…testmetal made it work…very nice tool, especially with double curve…if we could ever control individual lines with different tapers it would be brilliant
ps.what does testmetal do ?

Hi Giusseppe -

The current test command is just a rough prove-of-concept prototype and a finished version would have more controls.

The TestMetal command makes Rhino use a display pipeline that uses the Metal framework on macOS instead of the OpenGL framework. In the past, bugs in Apple’s OpenGL support have been hard to work around, and with Apple Silicon, Rosetta 2 converts OpenGL calls to Metal. By using Metal directly, we hope to have a more stable display pipeline for Rhino on Mac. The Metal implementation should benefit both hardware running on Intel and on Apple Silicon.

thanks for the explanation Wim.
In the 3d sketching video there is the use of Showzbuffer. he then inverts it to get the change of focus on lines. On my mac I cannot seem to get invert to work with this command because that option does not show so if I type invert it just inverts selections.I see (invert) on his windows command line…can I get the same command line to show on a mac ?

Hi Giusseppe -

Yes, you can. You have to run the -ShowZBuffer command. That is, not just ShowZBuffer.

thanks Wim….I had been trying _ in my macro……so I guess - before a command pauses for extra input.
Is there a list of test commands somewhere ?

Hi -

Generally, not, no. A dash will force the use of the command line by suppressing any dialog boxes. For commands that do not have a dialog box, the dashed version, in some few cases, will provide more options.

No, there isn’t. Most often, test commands are not useful for anything other than testing and the developers will not have made sure to capture all crashing and other issues to the same degree as they would have done with a regular command. They can be nice to play with once in a while but they are not supported because it’s known that there are (very many) unresolved issues with those commands.


It´s a beatutifill Tool. great for make illustrations and diagrams, It looks great combined with the _TweenCurves.
It wil be great if each curve can have it own settings.

Great Work!


Hi what’s new cammand for Test fancy curve
This cammand now doesn’t work in wip!

this has been added to linetypes now.

set your linetype to be custom, then check tapers. set your width to zero, your taper width to something like 4 and end width to zero.

you can set up different tapers and then assign them by layer and organize your line weights using layers, want a different line weight? simply move your curve to that layer.

in practice, I’ve created several different taper styles, then assigned them to a few layers, that way I can get thicker outer lines, thinner detail lines or other styles like fat to thin tapers, etc…