/usr/share/octave/packages/geometry-1.7.0/polygons2d/polygon2shape.m is in octave-geometry 1.7.0-1build1.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 | ## 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.
##
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## -*- texinfo -*-
## @deftypefn {Function File} {@var{shape} = } polygon2shape (@var{polygon})
## Converts a polygon to a shape with edges defined by smooth polynomials.
##
## @var{polygon} is a N-by-2 matrix, each row representing a vertex.
## @var{shape} is a N-by-1 cell, where each element is a pair of polynomials
## compatible with polyval.
##
## In its current state, the shape is formed by polynomials of degree 1. Therefore
## the shape representation costs more memory except for colinear points in the
## polygon.
##
## @seealso{shape2polygon, simplifypolygon, polyval}
## @end deftypefn
function shape = polygon2shape (polygon)
# Filter colinear points
polygon = simplifypolygon (polygon);
np = size(polygon,1);
# polygonal shapes are memory inefficient!!
# TODO filter the regions where edge angles are canging slowly and fit
# polynomial of degree 3;
pp = nan (2*np,2);
# Transform edges into polynomials of degree 1;
# pp = [(p1-p0) p0];
pp(:,1) = diff(polygon([1:end 1],:)).'(:);
pp(:,2) = polygon.'(:);
shape = mat2cell(pp, 2*ones (1,np), 2);
endfunction
%!test
%! pp = [0 0; 1 0; 1 1; 0 1];
%! s = polygon2shape (pp);
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