Rotate Perp Frames for Closed Curve Loft

Hello all,

I have a closed curve that I have divided and placed perp frames along the division point. Next, at each division point I've placed a profile curve that I would like to loft in straight sections. The issue I've encountered is when I opt for a 'closed loft' the beginning and end profile curves do not align correctly and I no longer get a loft between those profiles that result in planar surfaces.

Is there some adjustment to the rotation of the perp frames that can be done to align the section curves so that the entire loft is made up of closed, straight and planar lofted surfaces? Thanks for any help!

Note: In the image of the Rhino viewport, the troubled section of the loft is near the bottom of the image. You can see how the loft twists from the other profile sections.

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closedcurveloft_rhino.jpg, 848 KB
closedcurveloft.png, 37 KB

Replies to This Discussion

Permalink Reply by Riccardo Majewski on February 20, 2015 at 1:37am

Perpendicular frame component says "zero-twisting", so my solution here maybe will prevent you from having a developable loft (or planar surfaces), because I will rotate the frames.

Get 2 perpendicular frames, one at the start and one at the end of the curve (same location but different orientation/angle);

Pair the x component of the 2 frames (angle between x<>x), now you have the "angle error" that was causing your problem;

subdivide your curve with n perpendicular frames;

rotate each frame by a series of angles created by the angle / n;

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