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## Copyright (C) 2003-2011 David Legland <david.legland@grignon.inra.fr>
## 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.
##
## 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.
## -*- texinfo -*-
## @deftypefn {Function File} {@var{point} =} polygonPoint (@var{poly}, @var{pos})
## Extract a point from a polygon
## @seealso{polygons2d, polylinePoint}
## @end deftypefn
function point = polygonPoint(poly, pos)
# 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
Np = length(pos(:));
# number of vertices in polygon
Nv = size(poly, 1)-1;
# allocate memory results
point = zeros(Np, 2);
# iterate on points
for i=1:Np
# 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
endfunction
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