Deleting Unnecessary Edges

Posted by Sandra Winstead, SketchUp Team

Have you ever opened a SketchUp file that you didn’t create, or imported a model from another application, and found that it has hundreds of needless hidden or softened lines separating coplanar faces? Wish you could get rid of them with a simple ruby script? Now you can!

First, set up a few variables:

def variables
  @group_list = []
  @component_list = []
  @delete_these = []
  @model_list = Sketchup.active_model.entities
end

Then write a method that determines if an edge is 1) hidden or softened, and 2) bordered by two co-planar faces. If the edge meets each of those requirements, it is added to @delete_these list.

def delete_soft_lines(e)
  # Determine if the edge is soft or hidden, and if it is bordered by 
  # two faces.
  if ((e.soft? and e.faces.size == 2) or (e.hidden? and e.faces.size == 2))
    # Determine if the two bordering faces are coplanar.
    # Note: This will only catch cases where the front faces are pointing 
    # in the same direction.
    if (e.faces[0].normal.dot(e.faces[1].normal) > 0.999999999)
      # Add the edge to the list of entities that will be deleted.
      @delete_these.push(e)
    end
  end
end

Now create a method to find all the edges in the model, including edges that are embedded in groups and components:

def traverse_model_entities
  # @model_list will not be empty until all of the groups, components 
  # and edges have been traversed.
  while @model_list != []
    @model_list.each do |item|
      # Determine if the entity is an edge, group, or component.
      type = item.typename
      case type
        when "Edge"
          # Determine if the edge should be deleted, and add it to the 
          # @delete_these list.
          delete_soft_lines(item)
        when "Group"
          # Add each of the entities in the group into the group_list
          # array.
          item.entities.each do |entity|
            @group_list.push entity
          end
        when "ComponentInstance"
          # .entities can be called on a Component Definition, but not on
          # a Component Instance.
          # Use the .definition method to access the Component Definition
          # that the instance belongs to.
          item.definition.entities.each do |entity|
            # Add each of the entities in the component into the
            # component_list array.
            @component_list.push entity
          end
      end
    end
    # Update the @model_list so it contains only the entities that were 
    # embedded in groups or components. These entities haven't been
    # counted yet.
    @model_list = @group_list + @component_list
    # Clear out the group and component lists so they're ready for the
    # next level of sub-groups/components.
    @group_list = []
    @component_list =[]
  end
  # The edges that need to be deleted have all been added to the
  # @delete_these list, so erase those entities from the 
  # active SketchUp model.
  Sketchup.active_model.entities.erase_entities(@delete_these)
end

Finally, add a “Delete unnecessary edges” item to Tools menu, and pop a dialog letting you know the edges were deleted:

def delete_edges
  variables
  traverse_model_entities
  UI.messagebox("Edges deleted.")
end

UI.menu("Tools").add_item("Delete unnecessary edges") {delete_edges}