function vring = compute_vertex_ring(face)
% compute_vertex_ring - compute the 1 ring of each vertex in a triangulation.
%
% vring = compute_vertex_ring(face);
%
% vring{i} is the set of vertices that are adjacent
% to vertex i.
%
% Copyright (c) 2004 Gabriel Peyr
[tmp,face] = check_face_vertex([],face);
nverts = max(max(face));
A = triangulation2adjacency(face);
[i,j,s] = find(sparse(A));
% create empty cell array
vring{nverts} = [];
for m = 1:length(i)
vring{i(m)}(end+1) = j(m);
end