Hi Bryn
I think generic attributes, and nonreg unite provide a good way to do both workflows. The idea is that you can label all the faces on both bodies with some tag so that you can tell where all the faces in the result cam from. The summary documentation about generic attributes is at http://doc.spatial.com/qref/ACIS/html/ga__api_8hxx.html. The workflow as follows:
1) Use a distinctive label to label each face of each BODY that you are about to operator on. Use api_get_faces to get all the faces of each body. For each face use api_add_generic_named_attribute to add that the label for that BODY to the face. In a real application, it may make sense to label the body with the material it is made of or something else physically relevant. The code for this is something like
ENTITY_LIST faces;
api_get_faces(body1, faces);
ENTITY* this_face=NULL;
for( faces.init(); this_face=faces.next(); )
{
api_add_generic_named_attribute(this_face,"fromBody1", SplitCopy, MergeKeepAll );
}
The third and forth arguments to the api are very important because they specify that if you make a new face by splitting or merging this_face any resulting faces will have the same attribute copied on to them.
2) Do a non reg boolean unite to get one body where everything is imprinted together.
3) Use api_get_faces again to get all the faces on the result of the nonreg boolean. For each two sided face, look for the named attributes you gave to each BODYs faces.
You can find the attributes with
ATTRIB_GEN_NAME* returned_attrib=NULL;
api_find_named_attribute(this_twosided_face, name, returned_attrib);
where in this case name will either be "fromBody1" or "fromBody2". If the api call finds an attribute, the returned_attrib variable will be nonnull. A face which resulted from coincident faces on body1 and body2 will have both a "fromBody1" and "fromBody2" label attached. Interior faces which come from one or the other body can also be identified this way.
4) Remove any faces you don't want by using api_unhook_faces to take them out of the body and api_del_entity to delete the faces.
5) Call the faceter. For applications where you are making a tet mesh with the results it may be a good idea to use facet_options_precise and specify an aspect ratio, to help avoid getting triangles whose normal is inverted relative to their surface. You can get the mesh output in various formats using a mesh manager, but that is another long story. See http://doc.spatial.com/index.php/Mesh_Managers for more details. I would imagine you either want to use the default mesh manager (INDEXED), or a global indexed mesh manager (which will make one big array of vertices for all the points in the mesh and reference triangles from that. This is different from INDEXED_MESH_MANAGER where you get a separate mesh for each face, and the mesh edges along acis EDGE objects are duplicated.)
hope this helps
Eric
