For manual surface matching, and tidying up a surface’s messy CP structure, one can use the MoveUVN panel and the somewhat rather tedious woodpecker method (many mouse clicks) to transform CPs in Along tangent mode (just like with the Gumball (Object) mode), or in Along control polygon mode.
Direct manipulation like in other software has important features, where, for example, the three mouse buttons take over particular transformation tasks like XYZ, NUV. Is there a “Rhino way” to slide CPs along the U and V control polygon? DragMode with the UVN option is only just like using the Gumball, at least with V8 macOS?
I tried that mode, but the CP, when dragged, does not follow the little red (U) and green (V) indicators, so not along the control polygons. How exactly is that to be done?
When select Control Polygon, close the window, and then drag in that mode, the CP moves along the blue N vector. Does one need to press another key to “snap” it to the U or V control polygon?
They drag along the control polygon. It is a little tedious to extend in the direction of the control polygon, you’ll need to use the tab constraint for that.
(For future reference: in Rhino 9 the Gumball will align to the control polygon in object mode)
there are several layers of archaeological evolution and dust.
MoveUVN is the a old Gumball-proceeder-manipulation interface since early Rhino Versions…, and it is quite powerfull, but clunky.
MoveUVN and Gumball are independent - they do not interact / influence each other - as least as far as I understand.
…
(long time ago there was) TSplines and VSR/Direct Shape Modelling plug-ins - both acquired by Autodesk and died .. offered some gumball like Control Point / Polygon / Vertex (CP, CV ?) manipulation and great surface-matching.
McNeel came up with it s one gumball implementation… And maybe more love was spent to the new Gumball then to the overall topic of CV manipulation and integrating / updating the functionality of MoveUVN.
Still there are some powerful tools / plug-ins like Cyberstrak plug-in.
…
and hopefully v9 will shine in this aspect - still missing a lot like _matchSrf improvement …
workaround
to “slide” single CV I mostly use _scale with the center set to the target direction neighbor.
This is an old, but painful issue with control point modeling in Rhino.
As @Tom_P mentioned above, the best workaround to slide a control point along the control polygon precisely is to use the scale (I prefer “Scale1D”). It’s super tedious and inconvenient, at least in older Rhino versions like Rhino 7 (which I use currently).
An alternative is to activate the drag strength, set it to something like 10 or lower, then change the drag mode to “Control polygon”, then select the control point you want to move along the polygon, then drag it. That greatly reduces the real risk to move the control point in a random direction, which is a huge bug in Rhino, because its “Control polygon” mode is not capable of maintaining the sliding of the control points strictly along their control polygon. Often times the direction changes for no obvious reason, especially if the Osnap is active (which literally kills the ability to snap to a reference point while sliding the control point along its control polygon).
A reminder to the developers that secondary drag strength handles are super necessary for precise control point modeling. They allow the user have an instant access to two different drag strength settings (100% plus a custom %) at any time.
Not to mention that being able to switch between the different drag modes via a single mouse click on the “Mode” handle (if using the proposed Super Gumball) makes everything much faster and more convenient than the current implementation.
All right then, thanks @Tom_P and @Rhino_Bulgaria ; bit o’ ancient Rhino history in this topic… so, in a nutshell, to get close to direct CP manipulation in other software, it comes down to:
Transform CP… in the N, U, or V directions
DragMode off, not needed
Gumball (Object) on,
use the blue, red, and green arrows to move the CP.
DragStrength can be used, keep its window open.
Transform CP… along the U or V control polygons
DragMode on, set to Control Polygon,
Gumball off,
Shift to snap along the red and green lines to move the CP.
DragStrength can be used, keep its window open.
or
DragMode off, not needed
Gumball (Object) on,
Scale1D, with the Base point set to a target direction’s neighbour CP, and the reference point to the CP to be transformed.
So, together with Pascal Golay’s excellent script, this appears to be the “Rhino way” to work with unruly CP structures, and to perform manual matching with CPs.
