Cleaning up after intersect_with

lovebob

I've been working with intersect_with recently, and after much trial and error got something working.

I've been trying to make a hole of one shape inside another.

The problem is if I delete the cutting group used in intersect_with, it deletes all the interior faces, which kind of defeats the purpose. But if I don't delete the group, then I have to carefully delete and clean up the cutting shape and everything by hand, which also is not good, since I'm trying to handle all this programatically.
Specifically, if I do 'cutgroup.erase!' instead of 'cutgroup.explode' then I don't have any of the star's faces left, which is bad. I want to have a star shaped tube through the cylinder, not just a star shaped hole into the cavernous interior of the cylinder.

What are other people doing to clean up after doing intersect_with ?

model = Sketchup.active_model
entities = model.entities
entities.clear!

# Draw a cylinder                                                                                                                                                                                        
basegroup = entities.add_group
basegroupentities = basegroup.entities
center_point = Geom;;Point3d.new(0,0,0)
normal_vector = Geom;;Vector3d.new(0,0,1)
radius = 10
edgearray = basegroupentities.add_circle center_point, normal_vector, radius
first_edge = edgearray[0]
first_edge.find_faces # needed to create face between edges                                                                                                                                              
main_face = first_edge.faces.first
main_face.reverse! if main_face.normal.z < 0
main_face.pushpull 10
base_trans = basegroup.transformation

# Create the star                                                                                                                                                                                        
cutgroup = entities.add_group
cutgroupentities = cutgroup.entities
star_z = 0
pt1 = [0, 1, star_z]
pt2 = [-0.351, 0.509,  star_z]
pt3 = [-0.951, 0.309,  star_z]
pt4 = [-0.488, -0.209, star_z]
pt5 = [-0.588, -0.809, star_z]
pt6 = [ 0.0, -0.409,   star_z]
pt7 = [ 0.588, -0.809, star_z]
pt8 = [0.488, -0.209,  star_z]
pt9 = [ 0.951, 0.309,  star_z]
pt10 = [0.351, 0.509,  star_z]
base = cutgroupentities.add_face(pt1, pt2, pt3, pt4, pt5, pt6, pt7, pt8, pt9, pt10)
base.reverse! if base.normal.z < 0
base.pushpull 11
cut_trans = cutgroup.transformation

puts cutgroupentities.count
puts basegroupentities.count
cg = cutgroup.entities.to_a
bg = basegroup.entities.to_a
puts cut_trans.inspect
puts base_trans.inspect
puts cutgroupentities.count
puts basegroupentities.count
puts bg.size
puts cg.size

Sketchup.active_model.entities.intersect_with true, cut_trans, basegroup.entities, base_trans , true, bg


cutgroup.explode
basegroup.explode

thomthom

Did you post a similar question over at StackOverflow?

Btw, your profile says "SketchUp version: pre-6" - are you really using a SketchUp version older than 6?

lovebob

I have not posted a similar question on StackOverflow, I thought I would be more likely to get an answer here.

I'm using Sketchup 8.0.16845 on OS X. Whatever is in my profile is what the defaults are I guess, I only signed up last week and this is my first post.

I am pretty familiar with Ruby but have only very recently discovered that Sketchup has a Ruby API and started playing around with that.

sdmitch

Maybe this can be done using intersect_with but it is certainly not necessary.

model = Sketchup.active_model
entities = model.entities
entities.clear!

center_point = Geom;;Point3d.new()
normal_vector = Geom;;Vector3d.new(0,0,1)
radius = 10
edgearray = entities.add_circle center_point, normal_vector, radius
main_face = entities.add_face(edgearray)
main_face.reverse! if main_face.normal.z < 0
main_face.pushpull 10
star_z = 0
pt1 = [0, 1, star_z]
pt2 = [-0.351, 0.509,  star_z]
pt3 = [-0.951, 0.309,  star_z]
pt4 = [-0.488, -0.209, star_z]
pt5 = [-0.588, -0.809, star_z]
pt6 = [ 0.0, -0.409,   star_z]
pt7 = [ 0.588, -0.809, star_z]
pt8 = [0.488, -0.209,  star_z]
pt9 = [ 0.951, 0.309,  star_z]
pt10 = [0.351, 0.509,  star_z]
base = entities.add_face(pt1, pt2, pt3, pt4, pt5, pt6, pt7, pt8, pt9, pt10)
base.reverse! if base.normal.z < 0
base.pushpull 10

thomthom

@lovebob said:

I am pretty familiar with Ruby but have only very recently discovered that Sketchup has a Ruby API and started playing around with that.

I've not yet had time to test your code sample, but as an aside note - check out this summary about writing SketchUp plugins: http://www.thomthom.net/thoughts/2012/01/golden-rules-of-sketchup-plugin-development/

lovebob

Thanks sdmitch, that's a much easier way to do that!

I should have asked what I really wanted to know instead of providing a simplified example.
FYI this is all in the context of me wanting to make some things to 3d print.

Two questions really,

In the following code, is there a way to automatically remove the 3d text after doing the intersect so that I'm left with a solid rectangle that has the letters "Bob" punched through it?


model = Sketchup.active_model
entities = model.entities
entities.clear!

#Create a group to collect all entities for base cube                                                                                                                                                    
basegroup=entities.add_group
basegroupentities=basegroup.entities
p1 = Geom;;Point3d.new(0, 0, 0)
p2 = Geom;;Point3d.new(7, 0, 0)
p3 = Geom;;Point3d.new(7, 4, 0)
p4 = Geom;;Point3d.new(0, 4, 0)
points = [p1,p2,p3,p4]
base = basegroupentities.add_face points
base.reverse! if base.normal.z < 0
base.pushpull 1
base_trans=basegroup.transformation

cutgroup = entities.add_group()
cutgroup.entities.add_3d_text('Bob', TextAlignCenter, "Arial", true, false, 3.0, 0.0, 0.0, true, 1)
transform = Geom;;Transformation.new(Geom;;Point3d.new(0.5,0.5,0))
entities.transform_entities(transform, cutgroup)

cut_trans = Geom;;Transformation.new(Geom;;Point3d.new(0,0,0))
intersections = Sketchup.active_model.entities.intersect_with true, cut_trans, basegroup.entities, base_trans , true, basegroup.entities.to_a

cutgroup.explode
basegroup.explode

model.active_view.zoom_extents

I feel like these two are related. In this example I get close to what I want but the new faces created by the intersect_with remain on the cylinder, and when I delete them by hand I'm left without any faces inside the cylinder, which I think means the cylinder is not watertight and will not print. I want to delete all the faces outside the cylinder but retain the ones created by the intersect_with command inside the cylinder.


model = Sketchup.active_model
entities = model.entities
entities.clear!

basegroup = entities.add_group
basegroupentities = basegroup.entities
center_point = Geom;;Point3d.new(0,0,0)
normal_vector = Geom;;Vector3d.new(0,0,1)
radius = 1000
edgearray = basegroupentities.add_circle center_point, normal_vector, radius
main_face = basegroupentities.add_face(edgearray)
main_face.reverse! if main_face.normal.z < 0
main_face.pushpull 1000
base_trans = basegroup.transformation


cutgroup=entities.add_group
cutgroupentities=cutgroup.entities
p1 = Geom;;Point3d.new(500, -50, 500)
p2 = Geom;;Point3d.new(1500, -50, 500)
p3 = Geom;;Point3d.new(1500, 200, 500)
p4 = Geom;;Point3d.new(500, 200, 500)
points = [p1,p2,p3,p4]
base = cutgroupentities.add_face points
base.reverse! if base.normal.z < 0
base.pushpull 1000
cut_trans=cutgroup.transformation

baz = Sketchup.active_model.entities.intersect_with true, cut_trans, basegroup.entities, base_trans , true, basegroup

basegroup.explode
#cutgroup.explode                                                                                                                                                                                        
model.active_view.zoom_extents
cutgroup.erase!

Any ideas on how to automate these processes?
Thanks!

thomthom

The Pro version of SketchUp 8+ has solid boolean operation that let you add and subtract from solid meshes. If you could use them then it'd simplify things a lot instead of using intersect and manually cleaning up.

lovebob

@thomthom said:

The Pro version of SketchUp 8+ has solid boolean operation that let you add and subtract from solid meshes. If you could use them then it'd simplify things a lot instead of using intersect and manually cleaning up.

That's true but it costs 500 bucks too, so rather than do that I think I'd just learn blender or openscad or something.

I already know Ruby pretty well, so my preference is to use Sketchup, but if it's not possible to accomplish the equivalent of the 'subtract' functionality using the Ruby API in the free version then I guess I'll have to move on.

sdmitch

This seems to work with or without using intersect_with

model = Sketchup.active_model
entities = model.entities
entities.clear!

#Create a group to collect all entities for base cube
basegroup=entities.add_group
basegroupentities=basegroup.entities
base_trans=basegroup.transformation
p1 = Geom;;Point3d.new(0, 0, 0)
p2 = Geom;;Point3d.new(9, 0, 0)
p3 = Geom;;Point3d.new(9, 4, 0)
p4 = Geom;;Point3d.new(0, 4, 0)
points = [p1,p2,p3,p4]
base = basegroupentities.add_face points
base.reverse! if base.normal.z < 0
base.pushpull 1

cutgroup = entities.add_group()
cut_trans = cutgroup.transformation
cutgroup.entities.add_3d_text('Bob', TextAlignCenter, "Arial", true, false, 3.0, 0.0, 0.0, true, 1)
transform = Geom;;Transformation.new(Geom;;Point3d.new(0.5,0.5,0))
cutgroup.transform! transform

#intersections = cutgroup.entities.intersect_with true, cut_trans, basegroup.entities, base_trans , true, basegroup

basegroup.explode

dmp=cutgroup.explode;#erase the top and bottom of the letters
dmp.each{|f| f.erase! if f.is_a?(Sketchup;;Face) && f.normal.z.abs>0.5}
#add faces to 'holes' in the letters
dmp.each{|e| e.find_faces if e.is_a?(Sketchup;;Edge) && e.faces.length==1}

model.active_view.zoom_extents