Thank you very much, this is exactly what I'm looking for !

Thank you very much for this explanation and for the special case. It helps a lot.

Thank you very much for these complementary solutions. Renaud.

Thanks TIG!

And this diagram is a bit out of date. (There are some missing classes, and perhaps changes since it was drawn back in the v7 and v8 days.) http://www.sketchup.com/intl/en/developer/docs/diagram.php Also,... @iltis said: For example : ArcCurve (arcs and circles) is a subclass of the Curve class, and an edge is a part of a random curve ... Implies an incorrect assumption. The SKP document object hierarchy (ie, the model database tree) is a wholly separate construct than the Ruby class hierarchy and relationships. For example, the Sketchup::Edge class is not a sub-class of the Sketchup::Curve class. Both, are descendants of the Sketchup::Entity class. Sketchup::Curve and Sketchup::ArcCurve objects are special collection classes that connect edges together, but are not themselves an actual "model element". Sketchup::Edge objects are an actual model element, and so are a sub-class of Sketchup::Drawingelement.

I just saw that the .xaxis propery of the arcs are rotated => start_angle=0 is right, because the reference is wrong. OK, knowing that, I can see how to do this.

OK, this works well : begin # Open a file for writing File.open(filepath, "w"){ |file| selection = Sketchup.active_model.selection # Get an array of faces that are in the selection. faces = selection.grep(Sketchup;;Face) faces.each_with_index{ |face, index| # Write a label for the face. file.puts("Face#{index+1}") # Get a transformation object that translates from model space to 2d space of the face. t = Geom;;Transformation.axes(face.vertices.first.position, *face.normal.axes).inverse # Write all vertices to the file. blnFirstPoint = true first_point_u=0 first_point_v=0 face.outer_loop.vertices.each{ |vertex| # Get the point of the vertex and apply the transformation. point = vertex.position.transform(t) # Convert the coordinates u, v = point.to_a.map{ |c| c.to_f } if blnFirstPoint==true first_point_u = u first_point_v = v blnFirstPoint = false end #if # Write the coordinates to the file. file.puts("#{(u*10000*25.4).to_i.to_f/10000};#{(v*10000*25.4).to_i.to_f/10000}") } file.puts("#{(first_point_u*10000*25.4).to_i.to_f/10000};#{(first_point_v*10000*25.4).to_i.to_f/10000}") } } Thanks a lot! Renaud

@tt_su said: @dan rathbun said: fail() #re-raise the last exception Never seen that method used before. Is that different from just calling raise? raise() is an alias for fail() See the doc on the Kernel module: http://www.ruby-doc.org/core-1.8.6/Kernel.html#method-i-fail The best practices guides I have read, suggest that fail be used instead of raise, for readability, I suppose. But I really did not understand the logic in the guide. (I think it was something like "raise" has more meanings as a verb than "fail" ?)

Perfect! Thank you very much!