Offset tool on Voronoi sphere

Hi, I wonder if anyone can lend a hand...
...I'm relatively new to grasshopper and next to useless in it, and I'm having a bit of trouble offsetting polylines on a voronoi sphere...I want the curves to offset within the existing curves (to create a new surface to trim with the existing), however the offset seems to happen in both directions in some areas (see image below) does anyone have a magic method to stop this happening? I've attached a sketch of what I am ultimately trying to achieve... thanks! I've also attached the GH file at the bottom, if anyone could take a look I'd be forever grateful!

The offset lines are highlighted in green.

Attachments:

VORONOI OFFSET.gh, 18 KB

Replies to This Discussion

Permalink Reply by Laurent DELRIEU on May 1, 2014 at 10:36am

Hi Matthew

I have no magical answer, but it seems there is a bug in offset component of grasshopper. I include a geometry that led to show this bug with offset less than -10. There is not this bug in Rhino ! I hope that David Rutten will find a fix !

Permalink Reply by Laurent DELRIEU on May 1, 2014 at 10:38am

See the exemple of bug in file

Permalink Reply by Laurent DELRIEU on May 1, 2014 at 11:56am

I test with rhino functions, it seems to work better when you use this offset function

public Curve[] Offset(
Point3d directionPoint,
Vector3d normal,
double distance,
double tolerance,
CurveOffsetCornerStyle cornerStyle)

hope it helps. But there will be still strange things with little polygon !

Attachments:

VORONOIOFFSET_v2.gh, 14 KB

Permalink Reply by Matthew J Mouncey on May 2, 2014 at 5:54am

Hi, thanks for this, yes in the end I went down the route of scaling the faces around the centre points...worked a lot cleaner!

I have another problem now...I have extracted the midpoints of the edges of each surface (see image below) I now need to draw a line between one midpoint on one surface to the nearest midpoint on the next surface (perpendicular). However all the points are in one set and I'm unsure how to split them to do this...any pointers? Thanks!!

See screenshot below.