Problems with Offsetting Curves

Hi,

I am currently working on a Grasshopper script to section a shape on the y and Z planes. I have gotten all the way to making brep curves of the sections in both planes. I am making an offset, which will allow me to make a surface. When I put the offset function into the script it creates offsets in the Z plane with no problem, but I run into issues with the Y plane. It creates offsets inside the original brep curves for 2,3,4, and 6 which is what I want. However for some reason the offsets for the 0,1 and 5 curves are outside the original brep curves. I have tried grafting the offset, which didn't help. I also tried to change the offset distance from a negative to a positive, which only reverses the problem to the other curves. I have attaches a picture for reference, the green lines are the offset curves and the red are the original breb curves.

Thanks for any help you can give me!

Attachments:

Screen Shot 2016-04-07 at 5.16.54 PM.png, 98 KB
Screen Shot 2016-04-07 at 5.17.44 PM.png, 82 KB

Replies to This Discussion

Permalink Reply by ng5 Alex on April 7, 2016 at 5:54pm

Hello Kyle,

you can offset with both +- values you are after, so that you get both inside and outside offsets for all curves. Then you pick the ones with the largest or the smallest length (outside or inside).

you can also use one these two plugins, which have nice offset components.

clipper

bowerbird

best

alex

Permalink Reply by Armin Seltz on April 8, 2016 at 2:45am

Offset has also given me a lot of troubles before, when it starts randomly failing, so I also use Clipper and Bowerbird.

Only thing to mention is that Clipper only does Polyline offsets, so is best used for curves that are not smooth. What you can do though is explode the polyline and then use the vertices in a interpolate or nurbs curve.