GMSH exporter

Chris Fullmer

I'm not sure which will be more helpful, but play around with Face.outer_loop and Face.loops.

https://developers.google.com/sketchup/docs/ourdoc/face

Outer look should return just the outer loop around a face. Loops should return an array of loops that bound the face, meaning if there are holes in the face, it will return the loop around those holes. It looked like gmsh didn't want faves with holes though. So you might triangulate your model first to get rid of holes in faces. Or I suppose you could just triangulate faces with holes in them?

Chris Fullmer

Though I guess if you're using the quicker polygon mesh then the standard sketchup face loop might not help? I'm not too sure how that would all interact.

bomastudio

Ok. Now I'm working with the mesh. But the problem of the ordering, as GMSH needs, the edges of the mesh is still pending..... can you suggest how to solve?

TIG

Face.outer_loop.edges returns the edges in ccw order: edges have .start and .end vertices, .length and .line [start+vector] etc...
Face.outer_loop.vertices is similar for vertices - pt=vertex.position gives a Point3d and apt=pt.to_a returns an [x,y,z] array.
If your file format needs YZ flipping adjust the array into [x,-z,y] to solve this...
Point coordinates are in always inches [irrespective of the model's units] BUT these can be converted to other unit formats - e.g. .to_m. To make the 'number' into a string use .to_s on it...

Chris Fullmer

If he's already got his mesh put together, would it make sense to use that object to then write all the vertices? Something like this will display them to your console for testing. the mesh I use in the first line is your mesh object.

mesh.polygons.each_with_index do |e,index|
 unless e==nil
  puts ""
  puts "Face #{(index+1).to_s}"
  e.each_with_index do |pt, index2|
   puts "Vert# #{pt.to_s} - " + mesh.polygon_points_at(index+1)[index2].to_s
  end
 end

end

bomastudio

Hi guys
I'm returning on this plugin. I added the license (GLP2), so it's open source

Do you think it is a good idea to map the nodes with a Dictionary? As in IGES_EXPORT plugin http://sketchucation.com/forums/viewtopic.php?f=323&t=43307&hilit=iges?

su2gmsh.rb

Djskippy

Hi Bomastudio,

Some time ago I've written an export script from Sketchup to Gmsh.

Sketchup Groups are exported as Volumes in Gmsh
Sketchup Faces are exported as plane surfaces in Gmsh
Sketchup Edges are exported as lines in Gmsh
Sketchup Vertices are exported as points in Gmsh

The script handles nested groups and applies all transformations to the points in Gmsh
Inner faces are exported correctly.
It even exports text entered in Sketchup (not 3D text).

The only thing this script doesn't do is: Export circles and arc's as Gmsh circles, it now just exports them as lines and points (that's how Sketchup see's them).
To correct this you'll need to take a look a IGES_EXPORT and how it exports circles, cylinders and cones.

Gmsh Export script for Sketchup

Jsgodwin

Thanks for posting this! When opening the .geo file in gmsh, visually everything looks correct, but gmsh lists errors when reading the line loops.

Djskippy

@jsgodwin said:

Thanks for posting this! When opening the .geo file in gmsh, visually everything looks correct, but gmsh lists errors when reading the line loops.

You could give my exporter a try, the line loops are exported correctly.

bomastudio

@djskippy said:

Hi Bomastudio,

Some time ago I've written an export script from Sketchup to Gmsh.

Sketchup Groups are exported as Volumes in Gmsh
Sketchup Faces are exported as plane surfaces in Gmsh
Sketchup Edges are exported as lines in Gmsh
Sketchup Vertices are exported as points in Gmsh

The script handles nested groups and applies all transformations to the points in Gmsh
Inner faces are exported correctly.
It even exports text entered in Sketchup (not 3D text).

The only thing this script doesn't do is: Export circles and arc's as Gmsh circles, it now just exports them as lines and points (that's how Sketchup see's them).
To correct this you'll need to take a look a IGES_EXPORT and how it exports circles, cylinders and cones.

Thanks!!!!! I was looking for this plugin for a long long time!!!!