"Split Brep" leaves the split component open

In Rhino, if I split a solid Brep with a surface, I’m left with 2 closed pieces.

If I do the same thing with the Grasshopper “Split Brep” component, I’m left with 2 pieces each open at one end (at the split)

I think this is a bug.


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In Rhino, if I split a solid Brep with a surface, I’m left with 2 closed pieces.

Rhino always splits as open. Are you sure you are not thinking of the “booleansplit” rhino command? That one splits solids as closed parts. The grasshopper component does what Rhino’s regular “split” command does.

If you want to have solid just use a cap component after the split.

Yes you’re right I did a “boolean split” in Rhino.

I guess it just hopeful thinking on my part that the Grasshopper component was doing a boolean split.

I know I can cap the results if I’m splitting with a flat surface, but I first ran into the “problem” while splitting a Brep with another Brep composed of curved surfaces. “Cap” will only work if the openings are planar. It gets real messy (with Grasshopper) trying to split things up and join the right pieces back together.

Oh well–maybe someday McNeel will provide a “boolean split” component. (Or I could just write my own)


You might want to try this.

I found an easy method to “boolean split” 2 Brep objects with Grasshopper.

Find the solid intersection of the 2 objects and then subtract (solid boolean difference) the intersections from each of the 2 objects. Merge the intersections and the differences
to get a list of split solid objects. (Unlike the Rhino boolean split, this method won’t work for splitting with surfaces.)

Thanks everyone for your help.