mesh_vertex_neighbours

 mesh_vertex_neighbours - find all immediate neighbours of a vertex

 [nI,nXYZ,nD] = mesh_vertex_neighbours(FV,index)
 
 FV is a struct with fields:

 FV.vertices   - Nx3 matrix of Cartesian vertex coordindates (X,Y,Z)
 FV.faces      - Mx3 matrix of triangulation of FV.vertices
 FV.edge       - NxN sparse matrix of edge lengths (see mesh_edges)

 [nI,nXYZ,nD]  - vertex neighbour Indices, XYZ coordinates and Distance
                 from vertex

0001 function [nI,nXYZ,nD] = mesh_vertex_neighbours(FV,index),
0002 
0003 % mesh_vertex_neighbours - find all immediate neighbours of a vertex
0004 %
0005 % [nI,nXYZ,nD] = mesh_vertex_neighbours(FV,index)
0006 %
0007 % FV is a struct with fields:
0008 %
0009 % FV.vertices   - Nx3 matrix of Cartesian vertex coordindates (X,Y,Z)
0010 % FV.faces      - Mx3 matrix of triangulation of FV.vertices
0011 % FV.edge       - NxN sparse matrix of edge lengths (see mesh_edges)
0012 %
0013 % [nI,nXYZ,nD]  - vertex neighbour Indices, XYZ coordinates and Distance
0014 %                 from vertex
0015 %
0016 
0017 % $Revision: 1.1 $ $Date: 2004/11/12 01:32:35 $
0018 
0019 % Licence:  GNU GPL, no implied or express warranties
0020 % History:  04/2004, Darren.Weber_at_radiology.ucsf.edu
0021 %
0022 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
0023 
0024 
0025 if ~exist('index','var'),
0026     fprintf('...no index specified, using vertex 1\n');
0027     index = 1;
0028 end
0029 if isempty(index),
0030     fprintf('...no index specified, using vertex 1\n');
0031     index = 1;
0032 end
0033 
0034 if ~isfield(FV,'edge'),
0035     FV.edge = mesh_edges(FV);
0036 end
0037 
0038 Nvert = size(FV.vertices,1);
0039 
0040 fprintf('...finding vertex neighbours...'); tic;
0041 
0042 % the indices of the neighbours
0043 nI = find(FV.edge(index,:))';
0044 
0045 % the coordinates of the neighbours
0046 nXYZ = FV.vertices(nI,:);
0047 
0048 % only return unique vertex coordinates
0049 %[nXYZ, i, j] = unique(FV.vertices(nI,:),'rows');
0050 
0051 % extract neighbour edge lengths
0052 nD = full(FV.edge(index,nI))';
0053 
0054 
0055 t = toc; fprintf('done (%5.2f sec).\n',t);
0056 
0057 return