Offset Curves by moving

Hey everybody,

I try to get an offset from a closed polyline. But everytime I use the offset component the lines partly overlap and intersect.

Now I try to explode the geometry, evaluate each curve and move it individually to the center point.

The next step should be to cut the overlapping rest of each curve.

In the end I should get a clear offset, no overlapping parts, but also the same number of points.

I hope I was able to make clear what I wanted to say.

Please help me...

Attachments:

Different_Offset.png, 94 KB

Replies to This Discussion

Permalink Reply by Armin Seltz on August 4, 2016 at 8:00am

Its hard to tell without a .gh file - could you attach the file that is shown in the image. But looking at that it all looks like correct behaviour to me. Because you offset by such a large distance, the shape can end up being different. Otherwise you just have to scale it down if you want to retain the shape.

What are you trying to achieve? Can you draw the end result you are looking for? Offset curve is a bit tricky sometimes - there is a offset polyline plugin that works really well - I forgot the name now.

Permalink Reply by Philipp S on August 4, 2016 at 9:27am

First of all thanks for your reply.

The result I try to achieve is attached.

I hope you remember :)

Attachments:

Offset_Rhino.3dm, 940 KB
Offset_Grasshopper.gh, 10 KB

Permalink Reply by Armin Seltz on August 4, 2016 at 11:53am

I cant check the GH file right now, but remembered the plugin. Its called Clipper and you can find it here: http://www.food4rhino.com/project/clipper?etx&ufh (you need to sign up to download). Lots of other cool plugins there. Clipper will probably do what you want.

Permalink Reply by Philipp S on August 5, 2016 at 1:29am

Thanks a lot. But I only can use the first grasshopper release of this version. Otherwise it says that my rhino installer engine might not be compatible with the clipper installation file.

But even the grasshopper version doesn't show me the expected result...

Maybe you have another idea?

Thanks for your great help.

Permalink Reply by Armin Seltz on August 5, 2016 at 5:20am

Ok, so I had a look at the file. Its a difficult one, because you are looking for the "negative offset" if I can call it that. The question is how parametric you want your solution to be, ie. should this work also with other shapes, where a "negative offset" is theoretically possible. Because that dictates, wether you want a solution that works with just your case or with all cases.

If it should just work with this specific case I would say to just get the intersection points of the 3 curves and draw a shape from that. If it should be more flexible then it will be more difficult I guess.

Permalink Reply by Philipp S on August 6, 2016 at 4:51am

I'm sorry for the late replay. But thanks again for your help.

And yes it should work unfortunately for all shapes (closed planar polylines).

Thank you very much.

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