Split surfaces at the intersection with other surfaces

Hey guys,

I think that I need your help.

What I am trying to do is to cut surfaces at the intersections with other other surfaces.

All surfaces are collected as one list of data (Open Breps).

I have tried with VBcomponent and extruding surfaces to solid and then applying boolean operations, but each way does not solve the problem.

I reckon your experience might be very useful and maybe you will be able to help me.

I attatch prinstcreen I rhino and grasshopper file (I use rhino 4 SR9 and grasshopper 0.9.0014)

Best,

Lukas

Attachments:

rhino file for grasshopper.3dm, 567 KB
split surfaces at intersect.gh, 121 KB

Replies to This Discussion

Permalink Reply by Lukasz on December 16, 2012 at 7:30am

maybe this is the begining of the journey. Instead of open breps (after rebuilding arcs and applying loft operation) I ended up with untrimmed surfaces. (I attatch updated files)

Does anyone know how to handle this ?

Attachments:

rhino file for grasshopper.3dm, 567 KB
split surfaces at intersect2.gh, 121 KB

Permalink Reply by Chris Tietjen on December 16, 2012 at 9:58am

I took a look at your definition and it appears to me that you're going to have a lot of trouble generating surface splits as very few surfaces completely intersect each other. Hence the curves generated by intersections for splitting are insufficient. What is the final effect that you are trying to create? My guess is that you want to open the space under the canopies.

Permalink Reply by Chris Tietjen on December 16, 2012 at 10:13am

Permalink Reply by Lukasz on December 16, 2012 at 11:22am

Chris, thank you for your reply,

We can say that I am trying to open space under the canopies, but only to some extent. Some parts of the structure I planning to keep, but some -remove (at this point I think that I will do it manually). But the greatest problem for me is to divide the surfaces.

Can it be done without scripting?

Permalink Reply by Chris Tietjen on December 16, 2012 at 11:46am

You can divide the surfaces but not with curves that don't go from edge to edge.

Permalink Reply by Chris Tietjen on December 16, 2012 at 12:33pm

You can try the extend curve component with the smooth option set.

Permalink Reply by Lukasz on December 16, 2012 at 11:48am

I have found this trace:

1. I extruded surfaces to breps

2. union solid

3.extract all surfaces from brep

But now I have a problem: how to cull surfaces that are resulting from extrude operation. Can I do it by calculating mean normal vector and culliing unnecessary ones?

Attachments:

split surfaces at intersect2.gh, 123 KB

Permalink Reply by Chris Tietjen on December 16, 2012 at 12:56pm

Culling by the mean normal vector seems like it should work. Nice solution by the way.

Permalink Reply by Lukasz on December 16, 2012 at 1:17pm

Thanks once again Chris, I really appreciate your help.

I've solved it with solids, but that problem is that I end up with some trimmed surfaces that look like those on the image below.

Hence, I think I will go in your direction.

Another thing is that I am not experienced with list and looping in grasshopper, thus can you suggest some solution how to: perform brep|brep operation on a data collected in one list, that item x (from List A) is analysed with all items from List A apart from item x. And again for others items in the list. (So I end up with inputs A and B for Brep|Brep component).

Below solution for theprevious idea if sb needs this