Generating a "mesh-like" SweepOneRail

Rhino Developer
1

Dear all,

I am using the SweepOneRail class in order to generate the surface above. There are two section curves (the thick black lines) and a rail curve (hidden here).

Instead of generating a NURBS, I would like to generate a mesh out of the same geometrical transformation.
Please note that I am not interested in post-rationalizing this surface but in generating the mesh upfront. So in other words, I would like to get only the planes - or intermediate cross-sections - from this geometrical transformation and not the surface. I would like to be able to play with the resolution of those, increase and decrease locally the density of the planes/cross-sections.

Besides the SweepOneRail class, I couldn’t find any interpolation method that takes into account two profile curves as well as a rail curve. I tried to browse a bit openNURBS for some source code, but this was unsuccessful.

Does anyone here might know how I could perform such operation, and indicate me the maths behind the SweepOneRail class in order to retrieve only the planes?

Best,

Paul

2

Hi Paul,

You don’t find the code that generates the rail frames in openNURBS, as this is part of core Rhino.

Have you tried using Rhino.Geometry.Curve.PerpendicularFrameAt()?

– Dale

3

Hi Dale,

Thank you for your reply.

Unfortunately the two profile curves are oriented in a way that differs from the perpendicular frames of the rail curve.

I will try to tweak their orientation, but ultimately I think I would need to find a way to interpolate the two end frames along the rail curve, as SweepOneRail is actually doing…

Any other hints on this?

Paul

4

Hi Paul,

I believe the Sweep1 command creates rail frames using the same code behind Rhino.Geometry.Curve.PerpendicularFrameAt().

I’ll need to see some sample geometry - what you have and what you trying to accomplish - to be of more help.

Thanks,

– Dale

5

2016-08-18_13-40-38.jpg732×984 101 KB

Hi Dale,

Thanks for the help.
I finally managed to do what I initially wanted. The Rhino.Geometry.Curve.PerpendicularFrameAt() method actually worked.
I also had to interpolate the profiles on the XY plane and remap them onto the perpendicular frames of the input rail (see definition attached).

However - as the picture above illustrates - the final result doesn’t match perfectly what is generated with the SweepOneRail method (red surface). I would be interested to know where the difference is coming from, even if I am satisfied with the final mesh produced.

Best,

Paul

SweepQuadMesh.gh (8.2 KB)