bool
Skin::correct_face(Bface* f, bool& changed)
{
//
// BBBBBBBBBBBBBBB
// B /|
// B / |
// B f / | Change this, where quad face f
// B / | is adjacent to 2 boundary edgees...
// B / |
// B / |
// B/- - - - - - o
//
// BBBBBBBBBBBBBBB
// B\ |
// B \ |
// B \ | ... to this, where neither face of
// B \ | the quad is adjacent to more than 1
// B \ | boundary edge.
// B \ |
// B - - - - - - o
//
assert(f);
// boundary edges have flag == 1, others have flag == 0
uint n = num_edge_flags_set(f);
if (n < 2) return true; // not a problem
if (n > 2) {
// unfixable problem
err_adv(debug, " can't fix face with %d boundary edges", n);
return false;
}
// 2 boundary edges; get the non-boundary one:
Bedge* e = boundary_connector(f);
assert(e);
// we want to swap it; only possible if it has 2 faces:
if (e->nfaces() != 2) {
err_adv(debug, " can't fix edge with %d faces", e->nfaces());
return false;
}
// swapping won't do any good if its other face has boundary edges too:
if (!(num_edge_flags_set(e->f1()) == 0 || num_edge_flags_set(e->f2()) == 0)) {
err_adv(debug, " unfixable edge found, giving up");
return false;
}
// try to swap it:
if (e->do_swap()) {
err_adv(debug, " swapped edge");
return changed = true;
}
err_adv(debug, " edge swap failed");
return false;
}
