1## Copyright (C) 2021 David Legland
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27
28function pts2 = grFaceToPolygon(varargin)
29%GRFACETOPOLYGON Compute the polygon corresponding to a graph face.
30%
31%   PTS2 = grFaceToPolygon(NODES, EDGES, FACES, INDF)
32%   PTS2 = grFaceToPolygon(NODES, FACES, INDF)
33%   Where NODES, EDGES, and FACES are internal data of graph, and INDF is
34%   the index of the face to extract. The result is the (ordered) set of
35%   points composing the face.
36%
37%
38%   PTS2 = grFaceToPolygon(GRAPH, INDF)
39%   use structure representation for graph. The structure GRAPH must
40%   contain data for fields 'nodes' and 'faces'.
41%
42%   If several indices face indices are specified, result is a cell array
43%   of polygons.
44%
45%   The number of columns of PTS2 is the same as for NODES.
46%
47%
48% ------
49% Author: David Legland
50% e-mail: david.legland@grignon.inra.fr
51% Created: 2005-11-30
52% Copyright 2005 INRA - CEPIA Nantes - MIAJ (Jouy-en-Josas).
53
54%   HISTORY
55%   27/07/2007: cleanup code
56
57if length(varargin)==2
58    % argument is a graph structure
59    graph = varargin{1};
60    nodes = graph.nodes;
61    faces = graph.faces;
62    indf  = varargin{2};
63
64elseif length(varargin)==3
65    % arguments are nodes, faces and indices
66    nodes = varargin{1};
67    faces = varargin{2};
68    indf  = varargin{3};
69
70elseif length(varargin)==4
71    % arguments are nodes, edges, faces and indices, we forget edges
72    nodes = varargin{1};
73    faces = varargin{3};
74    indf  = varargin{4};
75end
76
77
78if iscell(faces)
79    % faces is a cell array
80    if length(indf)==1
81        face = faces{indf};
82        pts2 = nodes(face, :);
83    else
84        pts2 = cell(length(indf), 1);
85        for i=1:length(indf)
86            face = faces{indf(i)};
87            pts2{i} = nodes(face, :);
88        end
89    end
90else
91    % faces is an indices array: all faces have same number of vertices
92    if length(indf)==1
93        face = faces(indf, :);
94        pts2 = nodes(face, :);
95    else
96        pts2 = cell(length(indf), 1);
97        for i=1:length(indf)
98            face = faces(indf(i), :);
99            pts2{i} = nodes(face, :);
100        end
101    end
102end
103
104