Project to Brep trimming off part of Curve

Hi there,

I'm having a small issue with the Project (to Brep) command in grasshopper. Hopefully the snapshot below makes the intent and issue clear:

I have a set of lines that have been drawn in plan, and simply want to project this (z-axis) onto the Surface. All the lines project as intended except the guy down the center, which for some reason is cut short.

Interestingly, shifting the Brep slightly so the centre line is offset from centre of surface successfully projects the curve, but obviously, this is not a solution.

Also, previously extending the curve over the boundary of the surface seemed to work. This is no longer the case with this current surface.

Wondering if anybody could definitively confirm if this is a bug? In which case I'll have to look at rewriting the script. This is the start of a relatively extensive script so preferably would like to avoid.

Files attached below.

Thanks!

Attachments:

GHX ROOF.3dm, 313 KB
GHX trouble.gh, 17 KB

Replies to This Discussion

Permalink Reply by randers on March 22, 2017 at 10:07pm

Further testing shows that even modifying the script to instead use Brep/Brep or Brep/Plane Intersections to try and get the surface lines results in the same issue.

Ironically everything works fine when the surface being projected onto is less clean.

Permalink Reply by Hyungsoo Kim on March 23, 2017 at 3:29am

Hi.

It seems that your base untrimmed surface(probably a sphere?) is an invalid one. I don't know the exact reason.

I've modified your base surface and trimmed again and after that, missing projected curve no longer exist.

Your trirmming curves were internalised.

Attachments:

GHXtrouble_re.gh, 23 KB

Permalink Reply by randers on March 23, 2017 at 4:46am

Many thanks for your solution Hyungsoo. You're correct in your assumption that it was cut out from a sphere.

May I ask how you modified the base surface to become valid? I was under the impression that using a spherical surface, would, if anything create a cleaner surface to work with. This assumption was obviously wrong however my understanding of what constitutes an invalid surface is limited and I'd like to learn further to avoid in future.

Best,

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