get_verts.rb

    #get vertices
    def start
       #get vertices
       verts=[] #initialize vertices array
       trans_h=[] #initialize transformation array use to store hierarchy of transformations
       verts=createVerticesArray(sel,trans_h,verts)
    end

    def createVerticesArray(sel,trans_h,verts)
       sel.each{|ent|
          if (ent.is_a? Sketchup::Group) || (ent.is_a? Sketchup::ComponentInstance)
             trans_h.push(ent.transformation) #push the Group/Component tranformation onto the array
             ents=ent.definition.entities #get the entities in this Group/Component instance
             verts=createVerticesArray(ents, trans_h, verts) #recurse
          elsif (ent.is_a? Sketchup::Edge)
             ent.vertices.each{|vert| #begin analysis of vertices in this edge
                   puts vert if @debugFFD
                #get global position of the vertex by applying the hierarchy of transformations
                v_gpos=vert.position #returns local Point3d position of vertex
                   puts v_gpos if @debugFFD
                flat_t=flatten(trans_h) #get the flattened transformation for the hierarchy
                   puts flat_t if @debugFFD
                v_gpos.transform! flat_t #transform the vertex to get the global position
                vert.set_attribute("vert","gpos",v_gpos)
                verts.push(vert)
             }      
          end
       }
       #verts now contains redundant verts. remove duplicates.
       verts.uniq!         
       return verts
    end

    #thanks to Adam for the idea!
    def flatten(trans_h) #returns a flattened transformation from an array of transformations for the instance hierarchy
       flat_t=Geom::Transformation.new #create an entity transformation object
       
       #apply the hierarchy of transformations to the entity transformation
       trans_h.each{|t|
          flat_t=flat_t* t
       }
       return flat_t
    end