Adding physical group 'surface' by orientation criterion after loading .stp
Hello,
it would be great if there would be the possibility to do a selection of surfaces of a .stp geometry that depends on the orientation of a surface. On a cuboid, I would like to be able to select one of the six surfaces, and it should be, for example, the one facing to the right direction. Now, on a simple geometry, this, of course, is easily done by just clicking on it after activating the 'Add - Surface' dialogue in the 'Physical Groups' entry.
Having a complicated geometry, one that consists of thousands of surfaces enclosing a volume, it is impractical to select the collection of surfaces manually, which normals point more or less in the same direction. On the other hand, one could use this criterion (comparable orientation of normals) to select only those surfaces, that lie on the right side of the geometry. Is this, maybe, even possible with today's functionality of GMSH?
Another solution to this problem, that comes to my mind, would be to use the lasso selection while visualizing the surfaces with 'Aspect - Surface Display - Solid'. Looking from the right side onto the geometry, I could hit Ctrl and the left mouse button to select the set of surfaces I am looking at. Unfortunately, the lasso selection also selects every surface on the other side of the geometry, although all of these surfaces are, basically, invisible to the spectator (remember: the surfaces are visualized as solid).
I hope I could explain the problem I want to solve in a clear manner. Thank you for reading this and maybe there is already a nice solution to this problem implemented.