mesh_edges - Calculate edge lengths of triangulation
edge = mesh_edges(FV)
FV.vertices - vertices of mesh, Nx3 Cartesian XYZ
FV.faces - triangulation of vertices
edge - edge lengths, indexed by vertex
number (sparse NxN matrix)0001 function edge = mesh_edges(FV) 0002 0003 % mesh_edges - Calculate edge lengths of triangulation 0004 % 0005 % edge = mesh_edges(FV) 0006 % 0007 % FV.vertices - vertices of mesh, Nx3 Cartesian XYZ 0008 % FV.faces - triangulation of vertices 0009 % 0010 % edge - edge lengths, indexed by vertex 0011 % number (sparse NxN matrix) 0012 % 0013 0014 % $Revision: 1.1 $ $Date: 2004/11/12 01:32:35 $ 0015 0016 % 0017 % Licence: GNU GPL, no implied or express warranties 0018 % History: 07/2002, Darren.Weber_at_radiology.ucsf.edu 0019 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 0020 0021 tic; 0022 fprintf('...searching for mesh edges...'); 0023 0024 nvertex = size(FV.vertices,1); 0025 nface = size(FV.faces,1); 0026 0027 % the 'edge' matrix is the connectivity of all vertices 0028 edge = sparse(nvertex,nvertex); 0029 0030 for f = 1:nface, 0031 0032 % compute the length of all triangle edges (Diff is [3x3]) 0033 Diff = [FV.vertices(FV.faces(f,[1 2 3]),:) - FV.vertices(FV.faces(f,[2 3 1]),:)]; 0034 Norm = sqrt( sum(Diff.^2, 2) ); 0035 0036 edge(FV.faces(f,1),FV.faces(f,2)) = Norm(1); 0037 edge(FV.faces(f,2),FV.faces(f,3)) = Norm(2); 0038 edge(FV.faces(f,3),FV.faces(f,1)) = Norm(3); 0039 0040 % make sure that all edges are symmetric 0041 edge(FV.faces(f,2),FV.faces(f,1)) = Norm(1); 0042 edge(FV.faces(f,3),FV.faces(f,2)) = Norm(2); 0043 edge(FV.faces(f,1),FV.faces(f,3)) = Norm(3); 0044 end 0045 0046 t=toc; 0047 fprintf('done (%5.2f sec).\n',t); 0048 0049 return