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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 = circleToPolygon(circle, varargin)
%CIRCLETOPOLYGON Convert a circle into a series of points.
%
% PTS = circleToPolygon(CIRC, N);
% Converts the circle CIRC into a N-by-2 numeric array, containing the x
% and y positions of vertices.
% CIRC is given as [x0 y0 r], where x0 and y0 are coordinate of center,
% and r is the radius.
%
% If CIRC is a N-by-4 array, the fourth value is used as the angle (with
% respect to the x axis) of the first vertex, in radians. Default value
% is 0, corresponding to initial vertex with right-most position.
%
%
% P = circleToPolygon(CIRC);
% uses a default value of N=64 vertices.
%
% Example
% % simple example
% poly = circleToPolygon([30 20 15], 16);
% figure; hold on;
% axis equal;axis([0 50 0 50]);
% drawPolygon(poly, 'b');
% drawPoint(poly, 'bo');
%
% % add a rotation angle to the first vertex position
% figure; hold on; axis equal; axis([-12 12 -12 12]);
% poly = circleToPolygon([0 0 10 pi/4], 10);
% drawPolygon(poly, 'b'); drawVertices(poly);
%
% See also
% circles2d, polygons2d, circleArcToPolyline, ellipseToPolygon
%
% ------
% Author: David Legland
% E-mail: david.legland@inrae.fr
% Created: 2005-04-06
% Copyright 2005-2023 INRAE - BIA Research Unit - BIBS Platform (Nantes)
% check input size
if size(circle, 1) > 1
error('require circle to be 1-by-3 numeric array');
end
% determines number of points
N = 64;
if ~isempty(varargin)
N = varargin{1};
end
% angular shift for initial vertex
t0 = 0;
if size(circle, 2) > 3
t0 = circle(1, 4);
end
% create circle
t = linspace(0, 2*pi, N+1)' + t0;
t(end) = [];
% coordinates of circle points
x = circle(1) + circle(3) * cos(t);
y = circle(2) + circle(3) * sin(t);
% format output
if nargout == 1
varargout{1} = [x y];
elseif nargout == 2
varargout{1} = x;
varargout{2} = y;
end
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