Enhancement: Smart Track "inner" Control Points

Using the Control Polygon mode the current way (RED Arrow) as shown below, would break a match. It is correct that way it is as the CV travels along the Control Polygon.

However movement in extended tangent direction is necessary for surface refinement and clean CV distribution. Edge CVs seem to already have that behavior, but the “inner” CVs do not.

I would like to propose adding the Smart Track behavior (BLUE Arrow) to this mode. This way high Quality Surface refinements would be possible without changing the current behavior.

Another way might be an additional “Tangent Extention” mode.

Best regards.


Hello - the way to do this now is to go ‘backwards’ in the tangent direction and hit Tab to lock the direction. I get that it is not as clean - I’ve become used enough to it to make it just work. We used to have (v5?) dragging along the extensions as well as on the polygon but that gets very unwieldy and misleading when the angle is very shallow… so we took that out and imposed the Tab version. It is much better, but I agree that a separate dedicated control handle for each would be nicer.


Hello Pascal, thank you for the quick reply.

In direct modelling moving CVs strictly along the Polygon is rather uncommon. The way I know it depends on the direction you aproach the CV from. Meaning if you come from the left, it uses the left Polygon and its tangent extension, coming from the right it uses the right one etc, there are only 4 ways afterall.

Is there a way to bring back the V5 way you describe and only use the “Tangent Extension” mode?

I do understand the misleading aspect, however coming from Automotive Surfacing, I would prefer the “Extention way”, as I know it works reliably and has been used for High Quality Surfacing for over 30 years.The current way actually impairs surface quality. I think the same is true for SubD modeling.

Having the new Edge Continuity Tool available in V7, this will also raise only more questions and confusion with users the way it works now, as the surface/match impairment will be obvious.

So, you can go on the extensions - drag your tangent point back towards the edge point - that is, the opposite direction from the one you want, a short distance. Hit the Tab key. Now, drag out along the extension.



Would the way you decribe work in increments too? With the Nudge options maybe? Say you have a CV, grab it, hit the TAB key, then move it back and position it 0,01mm along the tangent from the initial position?

What about rows of CVs? Will each Cv travel along its own tangent or along the one you pick closest to?

Yes. But for moving in increments , MoveUVN is more convenient. Nudge does have the ability to nudge along the CP but not the extensions.

Your initial subject implies using SmartTrack… I need to think about that, it might be a way to get things working in a convenient way. What I dislike, myself, about direct dragging (no dedicated handle) is that this is subject to the point drag threshold - that is not clean when moving small amounts. I’ve made my point dragging threshold smaller than default and often end up using DragStrength to allow smooth movement over a short (screen pixels) distance.,


Yes Move UVN has all the options I would like see, even the delta and the drag strength.

But the concept of moving the CVs with a slider is the crazied most unintuitive way I have ever seen.

I love that Rhino has a little tool for every problem, but the whole CV-modeling aspect in Rhino got a little out of hand.

Rhino has the Gumball (also very useful for other things too yes), Soft Move, Move UVN, UVN Mode(?), End Buldge, Control Polygon mode, Nudge UVN, additionally you have all the curve tools, now in V7 we will see several CV-Tools for SubD modeling etc.

And each of these of offers a totaly unrelated workflow to each other. I dont want this to sound mean, I understand that every CV-problem was solved step by step over time. But after all these years these tools should form a union. One mighty CV-Tool that solves all the CV-Situations, and combines all the tools mentioned above. This could also be used for SubD modeling, calling it Vertex, face etc.:

It works exactly like that in ICEM, moving the CVs along their tangents with a delta value, you just smudge along their Polygon you dont even touch the CV. The tangents dont even light up or anything. It it that intuitive, it just works.

EDIT: I found a little video that shows how the CVs are moved in ICEM, you dont need to select CVs, you push and pull near them: LINK


How about a CV-Gumball?

Behavior and feel would be exactly like the current Gumball. You select the CV and the Gumball pops up. Each direction has its own handle and the CV is moved by grabbing the handle, just like the current Gumball.

Delta values would also work. Negative values travel along the tangent, positive values extend the tangent.

Also the “Pulling Back” on the polygon to define the tangent would be avoided:

An additional workflow might be activating the CV-Gumball by Control-Polygon regions.

The orange line is the middle of the Control Polygon. Grabbing in one of the areas 1,2,3,4 would fully define a CV and activate the handle right away without letting go of the LMB, making it unnecessary to the select the CV and saving one click per CV-Movement. The other half across the orange boarder (purple) selects the next CV (red circle).

The colors shown are just for explanation. The initial look would be just turning on the CVs without any colors, then clicking in one of the areas (1,2,3,4), the CV-Gumball would get visible.


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This is a very good idea. And should be simple to implement. Wish I had the time… but some day I will.

Should be part of next weeks WIP though. :wink:

// Rolf

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Yes probably haha :rofl:

Rolf you are great!

Hello Pascal,

I tried CV modeling the way you described. It does work for single random adjustment, but not for precision modelling. Honestly if you do CV modelling for 8+ hours a day, this is not feasible. I’ve never come across a workflow that is this cumbersome.

  1. First I enter CV mode
  2. Then I pick a surface
  3. Then I turn on CVs

Why cant CV-modelling just be a command that turns on CVs, like Adjust End Bulge?

  1. Then I pick a CV, if need to adjust a row I pick 3-5 more CVs or probably have use some weird hot key

Why does CV-Modeling not offer a Slide Edge tool like in SubD modelling (again totally unrelated workflows and different tools for Surfaces, Curves and SubD)

  1. I then click the CV again (LMB) and move it back
  2. Then I hit the TAB key
  3. I then move the CV again to the desired position.

With a little improvement this could half the amount of clicks.

Unfortunately I dont see Rhino being capable of precision CV-Modeling at the moment.
And as long as not even a “Tangent Extention”-Mode is available, direct modeling in Rhino is no option.

However I would like to participate in improving the workflow if anybody is interested.