Rhino V7 still has this silly degree/control point behavior on polycurves

Polycurve segments degrees get all raised to the highest degree found in those segments.
This renders impractical a control point editing which would have been super easy if the segments had retained their initial degree :

From the user’s perspective, this is just plain silly and irritating.

Oddly enough, a polysurface made by extruding this polycurve would be easier to edit :


It makes sense from a programing sense. For control point editing purposes the polycurve is treated as a single multi-span curve with multi-knots. That enables the standard curve editing tools to be used. To exactly match each individual curve the degree of a single multi-span curve needs to be the same as the highest degree of the individual curves and the number of control points increased, Note that What when used on a polycurve reports the original degrees and number of control points of the individual curves. If the polycurve is exploded or ExtractSubCrv is used the individual curves have their original degree and number of control points.

I assume you are editing the extruded surface using solid points, not control points. Solid points are different than control points with less ability to control shape.

Perhaps you want the equivalent of solid points for polycurves?

An alternative is to explode the polycurve and edit the individual curves.

Hello David,

Sorry to be so down to earth, but it is already bad enough not to have sketch constraints in Rhino, not to be hindered by obscure programming issues.
Curves are not represented by their equations on screen, and that’s to be more user-friendly right ?
So then why not go all the way and let the poor souls edit the corner of two lines ?

…or how to turn a low-level modeling chore into a medieval torture.


Another topic on a similar/same subject. Wish: Command to show and edit polycurves as their simplified, exploded components

This looks like your request. https://mcneel.myjetbrains.com/youtrack/issue/RH-52064 It appears your request is almost enabled.

“TestPolycurvePoints” : Just tested it . Perfect. Some common sense at last !
I hope it will be made the default behavior, and a “RevertBackToProgrammerCentricSillyness” command be created for the nostalgia.

This should make headlines, by the way, not gradient hatches.

And now, for more bitchin’ and complainin’ : If you want to connect two straight edges of a polycurve, you still get useless extra segments.


This is nice…

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“2D sketch has been a core part of almost every 3D design system for decades”
Emphasis on “almost”…

This is what I miss most from SolidWorks, and it’s nice to see that Siemens has managed to make it even more intuitive and streamlined.
@DanielPiker had promissing stuff going on in that field for Rhino.
Wonder if this is ever going to see the light of day ?


“_SimplifyCrv” should merge straight segments together and get rid off the extra points.

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I know. That’s not the point.
Mundane operations like connect on two line segments should not require extra fidgeting.

Hi Olivier -

I’ve reported this as RH-60072.

Hey ! You’re taking all the fun out of me being a disgruntled old fart !

Well, I’m merely reporting these - not fixing them.
And I’m sure that if we fix it, we can make it into a test command and not tell you about it : )


Frantically trying to type “TestSketchConstraints” or similar in the V7 command line
…no luck

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I’ve failed to see the point of Connect for a while. Adding extra geometry for not much good reason, a bit like Extrude tapered, and you often don’t realise what a pig’s ear it’s made until you turn on the CPs . Just use Fillet with R=0 and be done with it.

Well, it does a decent job with few clicks as long as you’re not dealing with a polycurve which includes an arc.

Now, I don’t know about you guys, but I draw a great shitload of these.
Polygons with some rounded sides are kind of everywhere.
Now when you need to edit these critters, you’re out if luck because you often need to maintain the tangencies.

Ahh the wasted hours… Exloding, re-connecting, re-filetting…over and over and…

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And Rhino’s amnesia for centre snap to a polygon as soon as corners get filleted, even on something as simple as a rectangle, meaning more manual construction geometry.

I am amazed that more hasn’t been made of the announcement of the test command mentioned above. It’s a very fundamental change to the way that Rhino handles CP editing of poly curves when sub curves within it have varying degrees.


It blows my mind that when we have filleted 2D curves in Rhino we still cannot:

  • Edit radius of fillet

  • Edit radius of all selected and/or connected fillets

  • Match radius form one to another

  • Snap to implied sharp intersection (as if here was no fillet)

  • Covert fillets to flat chamfer (and back)

  • Unfillet

Also how can you explain to a new user that in this case you can go from a fillet of 2mm to a fillet of 3mm (As long as you don’t click on the fillet, but you click twice, outside of it instead, but you cannot go back to a fillet of 2mm:

This entire section of Rhino tools seems to have been abandoned in a very rudimentary state. If Rhino does not fix this, I can see being an area where a simple plugin could do wonders here. Especially with the new commands from GH approach being now in place, some of this stuff is really simple.



I know I know… this is my favorite trap phrase for developers. A very low shaming tactic on my part. I plead guilty.

Don’t be fooled by my tactics kids: Nothing is simple with computers, ever, because they are dumb AF.


Well, sketch constraints, including dimensions editing, exist in virtually every CAD program since 1995 ; so there’s that.

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…And 3D constraints, and robust fillets, and robust Booleans, and assemblies, instances…