Selecting faces by normals?

[Ciacnorris]

Hi guys,

I encountered another problem on my 3D works:

I got a shell-similar 3D object (its shape is similar to an half-sphere), and I need to select all external faces. Is there a faster way than doing it manually?

I mean something like select all faces whose normals are directed outside the sphere volume.

Any suggestions?

Thanks!

[sdmitch]

@ciacnorris said:

Hi guys,

I encountered another problem on my 3D works:

I got a shell-similar 3D object (its shape is similar to an half-sphere), and I need to select all external faces. Is there a faster way than doing it manually?

I mean something like select all faces whose normals are directed outside the sphere volume.

Any suggestions?

Thanks!

mod = Sketchup.active_model
ent = mod.entities
sel = mod.selection
bb=Geom;;BoundingBox.new
faces=sel.grep(Sketchup;;Face)
faces.each {|f| bb.add f.bounds}
ctr=bb.center; sel.clear
for f in faces
 sel.add f if ctr.vector_to(f.bounds.center).angle_between(f.normal)<90.degrees;
end

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