We noticed that DupBorder in R7 sometimes creates degree 3 curves from surfaces that are bounded by straight-line edges. in R6, the results would always be a degree 1 curve, i.e. a polyline.
In addition to the curves not being degree 1, DupBorder in R7 also adds 2 additional knots to every edge, at 1/3 and 2/3 the distance between the two corners. This happens from the Rhino command line, and also through rs.DuplicateSurfaceBorder()
When I run SimplifyCrv on such a border, the results is as expected, namely a closed polyline with the extra knots removed.
I am wondering why this is happening. Was this new behaviour deliberately introduced into R7, and why does DupBorder sometimes create tidy polylines, and sometimes it doesn’t?
Many thanks for looking into this.
dupborder_debug_R6.3dm (92.0 KB)