Sweep1 not working in closed curves?

Why doesn’t Sweep1 work on a closed curve like this example? When I this using the Rhino Sweep1 command it works. Also doesn’t work in Grasshopper1.


171230 Sweep1.gh (6.2 KB)

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171230 Sweep1_2017Dec30a.gh (10.2 KB)

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Right, so the reason is that you need to align your section with the seam of the rail (or the other way around)?

The section needs to be located at the start of the curve for ‘Sweep1’ to work. I could have moved the section curve but didn’t want to lose its orientation at that point so I moved the seam (start/end of the curve) instead.

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Thanks for explaining, Joseph.
I wonder why Sweep1 is working like that in Grasshopper. In Rhino I don’t need to care about that.

You will find many rhino commands are more robust than gh. Most likely because Rhino has had many more years of development. Grasshopper uses rhinocommon which is not always the same level of advancement as rhino itself. Here is whats currently available for sweep in rhino common. http://developer.rhino3d.com/api/RhinoCommonWin/html/Methods_T_Rhino_Geometry_SweepOneRail.htm

My guess is rhino moves the curve seam to the first profile for the sweep behind the scenes.

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