Ah nice! Thanks bernd for your support regarding the implementation. First part of communication with Fenics done
I just deleted my local feature branch. The next feature would be the implementation of cell and facet functions which are created by FreeCAD.
I saw that we have already NodeSet, Mesh Group and Mesh Region. They are all for marking some specific part of the mesh by hand, aren't they? But do they support an assignment from e.g. element to real/bool/int valued function? Mesh Group and Mesh Region furthermore are only available for gmsh meshs? And NodeSet only marks nodes, but you cannot mark them with some certain value.
I for myself thought about a fourth alternative: What about marking meshs by some "tool" parts? For this I would use the inside check of the Shape of a part. The mesh itself is given and these tool parts are only for marking the nodes/elements, but I think it is a good way to do it in a easy-to-use manner. (One of the main advantages is, that you still could do something with an external given mesh, without having the base geometry. Or the other way around you could generate some more or less good overlap with the mesh to generate an appropriate base geometry.)
Edit1: I would like to hear your comments on this
Edit2: Is there any possibility to draw only certain elements (i.e. to switch "off" the others in the ViewObject)?