Automatic Add Slash(es)

Rhino
1

In this example I want to make a _Sweep2.
The rails are the black curves, the upper one is ugly.
The shape is the blue curve.

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As expected the result is ugly.

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Add Slash will help, and it does:
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I added the slashes one by one, using Near and Perp osnaps.
The same process for every slash.

As a test, I made a few points on the upper curve, then made red lines from the points perpendicular to the other curve.
This is how I think the slashes should be.
Also the same process for every line.

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In _Sweep2, I now selected the ends of the red lines.
And as expected, I have the wanted surface:

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The slashes could be done automatically.
_Sweep2, _BlendSrf etc. were much more efficient.

2

thanks for writing this up. I’ve logged something similar for BlendSrf a while back RH-85593 BlendSrf auto planar sections.

The automatic add slashes seems a bit more complicated though for the general case. Imagine this case:

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What would you imagine there to happen?

3

i think it is not the best approach of starting on one rail and looking at the shortest / closest point on the 2nd rail.
this will introduce a hierarchy that is not wanted.

i totally agree sweep2 should support some more advanced features to orient the shapes / slashes.
planar and straighten of _blendsrf is somehow a startingpoint.

auto or smart slashes should consider and balance much more infos then just closest point:

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  • balance the speed / spacing distribution on both rails (“constant speed … vivid”) but do not allow self intersections / overtaking
  • minimize (quadratic) deviation from angle between slash and tangent to 90 degree / rectangular
  • look at the inner speed distribution
  • as it is a 3d-issue, spacial orientation should also be considered.

tough their is no “best solution” but a balance of some factors.

the screenshot shows a starting point might look, evaluating from some kind of inner / average curve…

rigid orientation

i always miss somethink like _extrudeCrvAlongCrv with 2 rails.
“constant shape orientation / rigid shape” or _extrudeCrvAlongTwoCurves…
or … a better a nice option for sweep2

would be nice to have some more options / influence on the surface

4

I’d love to see something like this crude mock up that allows you to place one or more slashes and it then auto applies other slashes via some sort of tween operation.

imagine that it auto populates the intermediate slashes with the ability to spec a number of slashes between each intentional slash you place.

3 Likes
5

Of course not.
In many cases this approach is good enough.
At least for a proposal that one can change afterwards.