It would be very handy to have grouped points (just like what the “Divide” command does) in the exact places where the “Add slash” function of “Sweep 2 rails” was used to add more control over the shape of the surface. Sometimes, the operation must be repeated to use a few extra curves to create more extrusions along the same rails, or if a replacement profile curve is being used instead of the original curve.
Attached here is a sample file where the intent is to create a car door rubber sealing with the “Sweep 2 rails” toll using two separate profile curves. Since for the moment Rhino still can’t handle more than one curve as a single profile (not to be confused with the consecutive profiles placed in different locations along the two rails), the operation must be repeated to create the outer and inner surfaces.
P.S.: Also, the addition of the “Straighten” option in “Blend surface” was a welcome improvement, and I can see it being useful for “Sweel 2 rais”, as well. When I extruded my two curves from the sample file here and then applied “Blend surface” to their edge with G1 on both ends, a “Straighten = 90” resulted in a pretty even distribution of the control points of the output surface.
As I mentioned in my original post, adding grouped points will let the modeler have a clear indication where is the location of the slashes used for a “Sweep 2 rails” operation. Then, these points could be used to repeat the command either with different settings or with different profile(s). Or, as seen in my sample 3dm file above, different profiles could be used as an input for two or more individual “Sweep 2 rails” operations, and the grouped points created during the first operation with added slashes could be used for the 2nd one to make sure the next “Sweep 2 rails” surface will follow the same rules for the distribution of the isoparms.
Without those grouped points used as a guide, the 2nd “Sweep 2 rails” operation with added slashes will differ from the 1st one, because the slashes would be added at some random locations that can’t repeat the exact position of the original slashes. Hopefully I explain it good enough this time. Sorry if my English is a bit confusing. It’s not my native language.
As for the “Straighten” option, “Sweep 2 rails” could really benefit from using it (just like how “Blend surface” benefits now), because it lets the user set sorf of slashes automatically with a single mouse click and this parameter could be easily edited with a numerical input.
could you not simply make an alias for sweep 2 that runs divide first?
I see a use case for having slashes be places automatically using divide as a back end… you divide the curve by a number, then add slashes in those locations. If you ran the tool again with the same settings on the same curves, you’d get the same locations on the b side of your sweep.
am I understanding this correctly?
(Your English is great…it’s my native language, and clearly I still don’t get it all the time… )
There are two “problems” with using the “Divide” command for cases where I want to build “Sweep 2 rails” surfaces:
When I run the “Sweep 2 rails” command and then notice that it’s heavily distorted and/or needs a few slashes added at key areas to add more control over the distribution of the isoparms, I’m forced to cancel the command, then run “Divide”, then run “Sweep 2 rails” again. Even if I don’t forget to use “Divide” preliminary, it still adds extra mouse clicks.
On longer curves (like me example above from the 3dm file) I would need to set “Divide” with a huge amount of points and then have to count which of them exactly would work properly. Also, most of the time one of the curves is shorter than the other one, so the distribution of the points added by “Divide” is quite different. That would force me to manually place a point between two existing points added by “Divide”, which again adds more mouse clicks and basically required two other commands (“Divide” and “Point”) to be used prior “Sweep 2 rails”. Also, even if I create 100 points with “Divide” along a curve, I would need to either select and delete the rest ones that I don’t need, or select and change colour of the new ones I want to use to mark the locations clearly. This only adds even more mouse clicks.
On the other hand, by having a dedicated option “Straighten” inside the “Sweep 2 rails” pop-up window, it would be a matter of a single mouse click to add more control over the isoparms. And no need to preliminary commands like “Divide” and “Point”.
Or, if adding slashes with the “Add slash” button automatically creates points in the same locations, these could be used to repeat the operation with exactly the same slashes.