How to use a Component to provide a generic face?

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1

I’ve been using a component definition to generate various solids that I move with a transform and instantiate. I wanted to do this for extruding a face, but am having problems.

For solids, I define a component that creates a face and pushpull’s it into a solid. I then add_instance the definition with a transform to put it where I want it.

What I tried to do to extrude a face was to make a component that just makes a face (add_face). I then add_instance it with a transform. I then try a followme on it to extrude, but the instance doesn’t seem to be a vanilla face anymore. I now see it as a “ComponentInstance”, not real surprising. I tried various ways of extracting the raw face but can’t. Any guidance on how to extrude it? Code below. Thanks.

  def self.create_component_definition_molding()
    @componentDefinitionMolding=@definitions.add "molding"
    moldingFace = @componentDefinitionMolding.entities.add_face [0, 0, 0], [1, 0, 0], [3, 0, 2],[8,0,4],[8,0,5],[7,0,5],[0,0,2],[0,0,0]
  end

  # Draw top/trim molding
  # Create a molding face
  self.create_component_definition_molding()
  @transform=Geom::Transformation.new([128,18,94])
  moldingFace=@entities.add_instance(@componentDefinitionMolding,@transform)
  UI.messagebox("moldingFace type: " + moldingFace.typename)
  # Create the extrusion path
  path = @entities.add_edges [128,18,94],[128,6.75,94],[0,6.75,94]
  # Extrude the molding along the rectangular path
  moldingFace.explode.entities[0].face[0].followme path     (line 426)

This results in:

Error:NoMethodError: undefined method entities' for #<Array:0x0000000cc55c90>> C:/users/gkd/sketchuprubyscripts/shelfUnitAnthony.1.rb:426:in module:Shelving’
C:/users/gkd/sketchuprubyscripts/shelfUnitAnthony.1.rb:12:in `<top (required)>’

:in `load' :in `' SketchUp:1:in `eval'

Update: Looks like you can’t “explode” in place, since changing the last line to the 2 below seems to work as expected:

  array=moldingFace.explode
  array[0].followme path
2

Explode returns an Array of Entity objects. You can’t run entities on that array since there is no entities method on Arrays.

This should work:

moldingFace.explode.find { |e| e.is_a?(Sketchup::Face) }.followme path

It also iterates the Entity objects returned by the explosion to find the one that is a face regardless of its index. However I would not use the variable name “moldingFace” for something that isn’t a face but a ComponentInstance.

1 Like
3

Works great. I see what’s going on now. Thanks.

4

Also, a question on extruding. The lower left corner of my face was at 128,18,94 after the transform. I then extruded with a path that had a Z coordinate of the lower left corner of the transformed face. I thought I had to match the lower left corner, but it seems it doesn’t matter. I changed the path’s Z coordinates to 0, and it still worked as expected. Is that because Sketchup knew I was extruding normal to the face (in the XY plane, since all Z values were equal)? What if I wanted to extrude with a path that had different Z values? What happens if I extrude with a path that doesn’t start with a point on the face? Any pointers to more detailed documentation on extruding? Thanks.

5

You can play around with the Follow Me tool in Sketchup to better understand how it works. If you’re only extruding along a single line you can also use pushpull.

6

Some further scripting experiments cleared things up. Here are my new “rules to extrude by”:

  • As expected, drawn faces have their normal based on the right hand rule: ccw vertex’d face → normal out.
  • Looks like extruding starts from the initial face, and then travels parallel to the path.
  • So, probably clearer to actually start the extrusion path from any point on the face.
  • And probably clearer to use a face point that is more interesting in the final solid.
  • If not using a path coincident with a face vertex, or later transform’ing the extruded solid, should delete the path by looping through edge.erase!'s so no longer visible.