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## Copyright (C) 2004-2011 David Legland <david.legland@grignon.inra.fr>
## Copyright (C) 2004-2011 INRA - CEPIA Nantes - MIAJ (Jouy-en-Josas)
## Copyright (C) 2012 Adapted to Octave by Juan Pablo Carbajal <carbajal@ifi.uzh.ch>
## 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.
## -*- texinfo -*-
## @deftypefn {Function File} {@var{d} = } edgePosition (@var{point}, @var{edge})
## Return position of a point on an edge
##
## POS = edgePosition(POINT, EDGE);
## Computes position of point POINT on the edge EDGE, relative to the
## position of edge vertices.
## EDGE has the form [x1 y1 x2 y2],
## POINT has the form [x y], and is assumed to belong to edge.
## The result POS has the following meaning:
## POS < 0: POINT is located before the first vertex
## POS = 0: POINT is located on the first vertex
## 0 < POS < 1: POINT is located between the 2 vertices (on the edge)
## POS = 1: POINT is located on the second vertex
## POS < 0: POINT is located after the second vertex
##
## POS = edgePosition(POINT, EDGES);
## If EDGES is an array of NL edges, return NE positions, corresponding to
## each edge.
##
## POS = edgePosition(POINTS, EDGE);
## If POINTS is an array of NP points, return NP positions, corresponding
## to each point.
##
## POS = edgePosition(POINTS, EDGES);
## If POINTS is an array of NP points and EDGES is an array of NE edges,
## return an array of [NP NE] position, corresponding to each couple
## point-edge.
##
## @seealso{edges2d, createEdge, onEdge}
## @end deftypefn
function pos = edgePosition(point, edge)
nEdges = size (edge, 1);
nPoints = size (point, 1);
if nPoints == nEdges
dxe = (edge(:, 3) - edge(:,1))';
dye = (edge(:, 4) - edge(:,2))';
dxp = point(:, 1) - edge(:, 1);
dyp = point(:, 2) - edge(:, 2);
else
% expand one of the arrays to have the same size
dxe = (edge(:,3) - edge(:,1))';
dye = (edge(:,4) - edge(:,2))';
dxp = bsxfun (@minus, point(:,1), edge(:,1)');
dyp = bsxfun (@minus, point(:,2), edge(:,2)');
end
pos = (dxp .* dxe + dyp .* dye) ./ (dxe .* dxe + dye .* dye);
endfunction
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