Loft then Join or Boolean corrupts surface


I had similar issue before, but that was when using loft from two closed curves.
The surface was a bit twisted. Used simplycrv to make the close curves, but still same.

This time, the loft makes a good surface, but when I try to join two surface created by loft,
the output surface becomes a bit twisted.

So making a closed curve -> loft -> then join. or boolean.

attached is rhino file, and some screen shots of analysis tool.


using WIP build 5B148w
question_loftandjoin.3dm (135.6 KB)

What you see are display artifacts caused by Rhino’s poor meshing of surfaces with internal G1 (tangent-only) joints. In the dialog for Loft there is a checkbox for “Split at tangents” - try checking that before executing the loft and see if that helps.

To fix the existing object, try DivideAlongCreases with SplitAtTangents=Yes.

HTH, --Mitch

Couldn’t get the checkbox for “Split at tangents” on the Loft, but
the DivideAlongCreases worked like a charm!!

Left is what was, Right is after DivideAlongCreases

Thank you!!!

I’ll try the Split at tangents option in the Loft for next project.


You are correct, this option is indeed missing from the dialog version of the command in MacRhino. It is present in the -dash (command line) version of the command. Filed as a bug.


OK, got it!

Thank you again.