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## Copyright (C) 2024 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 varargout = projPointOnPolyline(point, poly, varargin)
%PROJPOINTONPOLYLINE Compute position of a point projected on a polyline.
%
% POS = projPointOnPolyline(POINT, POLYLINE)
% Compute the position of the orthogonal projection of a point on a
% polyline.
% POINT is a 1-by-2 row vector containing point coordinates
% POLYLINE is a N-by-2 array containing coordinates of polyline vertices
% POS is the position of the point on the polyline, between 0 and the
% number of vertices of the polyline. POS can be a non-integer value, in
% this case, the integer part corresponds to the polyline edge index
% (between 0 and Nv-1), and the floating-point part corresponds to the
% relative position on i-th edge (between 0 and 1, 0: edge start, 1: edge
% end).
%
% When POINT is an array of points, returns a column vector with as many
% rows as the number of points.
%
% POS = projPointOnPolyline(POINT, POLYLINE, CLOSED)
% Specifies if the polyline is closed or not. CLOSED can be one of:
% 'closed' -> the polyline is closed
% 'open' -> the polyline is open
% a column vector of logical with the same number of elements as the
% number of points -> specify individually if each polyline is
% closed (true=closed).
%
% [POS, DIST] = projPointOnPolyline(...)
% Also returns the distance between POINT and POLYLINE.
%
% Example
% poly = [10 10; 20 10;20 20;10 20];
% projPointOnPolyline([15 0], poly)
% ans =
% 0.5000
% projPointOnPolyline([0 16], poly)
% ans =
% 3.0000
%
% See also
% points2d, polygons2d, polylinePoint, projPointOnPolygon
% distancePointPolyline
%
% ------
% Author: David Legland
% E-mail: david.legland@inrae.fr
% Created: 2009-04-30, using Matlab 7.7.0.471 (R2008b)
% Copyright 2009-2023 INRA - Cepia Software Platform
% check if input polyline is closed or not
closed = false;
if ~isempty(varargin)
var = varargin{1};
if strcmp('closed', var)
closed = true;
elseif strcmp('open', var)
closed = false;
elseif islogical(var)
closed = var;
end
end
% closes the polyline if necessary
if closed
poly = [poly ; poly(1,:)];
end
% number of points
Np = size(point, 1);
% allocate memory results
pos = zeros(Np, 1);
minDist = inf*ones(Np, 1);
% iterate on points
for p = 1:Np
% build set of edges
edges = [poly(1:end-1, :) poly(2:end, :)];
% compute distance between current point and all edges
[dist, edgePos] = distancePointEdge(point(p, :), edges);
% update distance and position if necessary
[minDist(p), edgeIndex] = min(dist);
pos(p) = edgeIndex - 1 + edgePos(edgeIndex);
end
% process output arguments
if nargout <= 1
varargout{1} = pos;
elseif nargout == 2
varargout{1} = pos;
varargout{2} = minDist;
end
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