Grasshopper

algorithmic modeling for Rhino

Hi,

I have a large number of surfaces I want to trim or split with a solid. I'm currently using BBX to get the intersections, which seems to work fine, but then if I try to split the surfaces with  SrfSplit all the surfaces are split with all the curves, even if the curves don't lie on the surface.  Is there a better way to do this?

Thanks,

Eric

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Replies to This Discussion

As long as the curve somehow projects onto the surface, it will split. You can prevent that by separating the surfaces and curves into matching tree structures.

...really depends how you want the curves to project and trim. If you want to control projection direction, you need to extrude the curves and do a solid trim.

Thanks, I guess it's time to learn about tree structures.

Eric

This is what I currently have.  How do I change the output of the intersect Breps and the Offset components to trees? How is a tree data structure defined?

Eric

Is there a reason for intesecting with a shifted list but trimming the full set of offsets? This will definitely mess up the matching.

Otherwise: if yo ucan drop the shift, just graft the offset output. This will create a branch for each slice and keep offset surfaces and intersection curves neatly organized and matched.

The shift is because the original input to Offset is included in the output and I am only interested in the results from the offset surfaces.

Then you should also use the shifted list as an input to the trim surface component. Or you should generate the offsets with a Series starting from Ply t. That way you will not get the original surface in the first place.

That works well, thanks.

Now to sort out the split surfaces that are inside the solid from the ones outside.

Area on the trimmed surfaces and BRep inclusion (Inside Component) for the returned centroids...

I wish it were that simple.  The centroid of the keepers is not necessarily inside the BRep. Think of curved slices of a 'J'-shaped pipe that are offset from the CL of the pipe.

I can set it up so the outside trimmed surface is always larger, and sort by area.

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