How to get alignment when dividing countoured curves?

Here’s a weird one. After using contour to produce a series of curves for a cylinder, dividing those curves produces different results depending on whether the cylinder was created using a primitive or a loft.

Specifically, the last divided curve starts and ends at an offset relative to the other ones if the contour was done on a loft.

This is impacting me on a more complex design, but the bad behavior scales all the way down to this simple example.

Any ideas?

dividetrouble.gh (8.6 KB)

Simple, avoid contours.

Or use Flip Curve:

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The actual issue is on a very complex surface where I don’t have section curves. I suppose I can section it myself with a series of planes and brep/plane intersections, but that seems to be reinventing contour.

…and thank you for the insight on using flip curve to normalize the contour results! I hadn’t seen that it was an issue of the first (and sometimes last) being flipped.

If the first instead of last curve were the wrong direction, they would all be wrong so choosing the correct guide curve is critical. I took the easy way and got lucky this time. Contours get weird.


dividetrouble_2020Dec15a.gh (11.1 KB)