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## Copyright (C) 2003-2017 David Legland
## All rights reserved.
##
## Redistribution and use in source and binary forms, with or without
## modification, are permitted provided that the following conditions are met:
##
## 1 Redistributions of source code must retain the above copyright notice,
## this list of conditions and the following disclaimer.
## 2 Redistributions in binary form must reproduce the above copyright
## notice, this list of conditions and the following disclaimer in the
## documentation and/or other materials provided with the distribution.
##
## THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ''AS IS''
## AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
## IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
## ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
## ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
## DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
## SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
## CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
## OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
## OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
##
## The views and conclusions contained in the software and documentation are
## those of the authors and should not be interpreted as representing official
## policies, either expressed or implied, of the copyright holders.
function edgeFaces = meshEdgeFaces(vertices, edges, faces) %#ok<INUSL>
%MESHEDGEFACES Compute index of faces adjacent to each edge of a mesh
%
% EF = meshEdgeFaces(V, E, F)
% Compute index array of faces adjacent to each edge of a mesh.
% V, E and F define the mesh: V is vertex array, E contains vertex
% indices of edge extremities, and F contains vertex indices of each
% face, either as a numerical array or as a cell array.
% The result EF has as many rows as the number of edges, and two column.
% The first column contains index of faces located on the left of the
% corresponding edge, whereas the second column contains index of the
% face located on the right. Some indices may be 0 if the mesh is not
% 'closed'.
%
% Note: a faster version is available for triangular meshes.
%
% Example
% meshEdgeFaces
%
% See also
% meshes3d, trimeshEdgeFaces, meshDihedralAngles, polyhedronMeanBreadth
% ------
% Author: David Legland
% e-mail: david.legland@grignon.inra.fr
% Created: 2010-10-04, using Matlab 7.9.0.529 (R2009b)
% Copyright 2010 INRA - Cepia Software Platform.
Ne = size(edges, 1);
% indices of faces adjacent to each edge
edgeFaces = zeros(Ne, 2);
% different method for extracting current face depending if faces are
% stored as index 2D array or as cell array of 1D arrays.
if isnumeric(faces)
Nf = size(faces, 1);
for i = 1:Nf
face = faces(i, :);
processFace(face, i)
end
elseif iscell(faces)
Nf = length(faces);
for i = 1:Nf
face = faces{i};
processFace(face, i)
end
end
function processFace(face, indFace)
% iterate on face edges
for j = 1:length(face)
% build edge: array of vertices
j2 = mod(j, length(face)) + 1;
% do not process edges with same vertices
if face(j) == face(j2)
continue;
end
% vertex indices of current edge
currentEdge = [face(j) face(j2)];
% find index of current edge, assuming face is left-located
b1 = ismember(edges, currentEdge, 'rows');
indEdge = find(b1);
if ~isempty(indEdge)
if edgeFaces(indEdge, 1) ~= 0
error('meshes3d:IllegalTopology', ...
'Two faces were found on left side of edge %d ', indEdge);
end
edgeFaces(indEdge, 1) = indFace;
continue;
end
% otherwise, assume the face is right-located
b2 = ismember(edges, currentEdge([2 1]), 'rows');
indEdge = find(b2);
if ~isempty(indEdge)
if edgeFaces(indEdge, 2) ~= 0
error('meshes3d:IllegalTopology', ...
'Two faces were found on left side of edge %d ', indEdge);
end
edgeFaces(indEdge, 2) = indFace;
continue;
end
% If face was neither left nor right, error
warning('meshes3d:IllegalTopology', ...
'Edge %d of face %d was not found in edge array', ...
j, indFace);
continue;
end
end
end
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