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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 point = polygonPoint(poly, pos)
%POLYGONPOINT Extract a point from a polygon.
%
% POINT = polygonPoint(POLYGON, POS)
%
%
% Example
% polygonPoint
%
% See also
% polygons2d, polylinePoint
%
% ------
% 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
% eventually copy first point at the end to ensure closed polygon
if sum(poly(end, :) == poly(1,:))~=2
poly = [poly; poly(1,:)];
end
% number of points to compute
nPoints = length(pos(:));
% number of vertices in polygon
Nv = size(poly, 1)-1;
% allocate memory results
point = zeros(nPoints, 2);
% iterate on points
for i = 1:nPoints
% compute index of edge (between 0 and Nv)
ind = floor(pos(i));
% special case of last point of polyline
if ind==Nv
point(i,:) = poly(end,:);
continue;
end
% format index to ensure being on polygon
ind = min(max(ind, 0), Nv-1);
% position on current edge
t = min(max(pos(i)-ind, 0), 1);
% parameters of current edge
x0 = poly(ind+1, 1);
y0 = poly(ind+1, 2);
dx = poly(ind+2,1)-x0;
dy = poly(ind+2,2)-y0;
% compute position of current point
point(i, :) = [x0+t*dx, y0+t*dy];
end
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