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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 = drawSphere(varargin)
%DRAWSPHERE Draw a sphere as a mesh.
%
% drawSphere(SPHERE)
% Where SPHERE = [XC YC ZC R], draw the sphere centered on the point with
% coordinates [XC YC ZC] and with radius R, using a quad mesh.
%
% drawSphere(CENTER, R)
% Where CENTER = [XC YC ZC], specifies the center and the radius with two
% arguments.
%
% drawSphere(XC, YC, ZC, R)
% Specifiy sphere center and radius as four arguments.
%
% drawSphere(..., NAME, VALUE);
% Specifies one or several options using parameter name-value pairs.
% Available options are usual drawing options, as well as:
% 'nPhi' the number of arcs used for drawing the meridians
% 'nTheta' the number of circles used for drawing the parallels
%
% H = drawSphere(...)
% Return a handle to the graphical object created by the function.
%
% [X Y Z] = drawSphere(...)
% Return the coordinates of the vertices used by the sphere. In this
% case, the sphere is not drawn.
%
% Example
% % Draw four spheres with different centers
% figure(1); clf; hold on;
% drawSphere([10 10 30 5]);
% drawSphere([20 30 10 5]);
% drawSphere([30 30 30 5]);
% drawSphere([30 20 10 5]);
% view([-30 20]); axis equal; l = light;
%
% % Draw sphere with different settings
% figure(1); clf;
% drawSphere([10 20 30 10], 'linestyle', ':', 'facecolor', 'r');
% axis([0 50 0 50 0 50]); axis equal;
% l = light;
%
% % The same, but changes style using graphic handle
% figure(1); clf;
% h = drawSphere([10 20 30 10]);
% set(h, 'linestyle', ':');
% set(h, 'facecolor', 'r');
% axis([0 50 0 50 0 50]); axis equal;
% l = light;
%
% % Draw a sphere with high resolution
% figure(1); clf;
% h = drawSphere([10 20 30 10], 'nPhi', 360, 'nTheta', 180);
% l = light; view(3);
%
%
% See also
% spheres, circles3d, sphere, drawEllipsoid
% ------
% Author: David Legland
% E-mail: david.legland@inrae.fr
% Created: 2005-02-17
% Copyright 2005-2023 INRA - TPV URPOI - BIA IMASTE
% extract handle of axis to draw on
[hAx, varargin] = parseAxisHandle(varargin{:});
% process input options: when a string is found, assumes this is the
% beginning of options
options = {'FaceColor', 'g', 'LineStyle', 'none'};
for i = 1:length(varargin)
if ischar(varargin{i})
if length(varargin) == 1
options = {'FaceColor', varargin{1}, 'LineStyle', 'none'};
else
options = [options(1:end) varargin(i:end)];
end
varargin = varargin(1:i-1);
break;
end
end
% Parse the input (try to extract center coordinates and radius)
if isempty(varargin)
% no input: assumes unit sphere
xc = 0; yc = 0; zc = 0;
r = 1;
elseif length(varargin) == 1
% one argument: concatenates center and radius
sphere = varargin{1};
xc = sphere(:,1);
yc = sphere(:,2);
zc = sphere(:,3);
r = sphere(:,4);
elseif length(varargin) == 2
% two arguments, corresponding to center and radius
center = varargin{1};
xc = center(1);
yc = center(2);
zc = center(3);
r = varargin{2};
elseif length(varargin) == 4
% four arguments, corresponding to XC, YX, ZC and R
xc = varargin{1};
yc = varargin{2};
zc = varargin{3};
r = varargin{4};
else
error('drawSphere: please specify center and radius');
end
% number of meridians
nPhi = 32;
ind = find(strcmpi('nPhi', options(1:2:end)));
if ~isempty(ind)
ind = ind(1);
nPhi = options{2*ind};
options(2*ind-1:2*ind) = [];
end
% number of parallels
nTheta = 16;
ind = find(strcmpi('nTheta', options(1:2:end)));
if ~isempty(ind)
ind = ind(1);
nTheta = options{2*ind};
options(2*ind-1:2*ind) = [];
end
% compute spherical coordinates
theta = linspace(0, pi, nTheta+1);
phi = linspace(0, 2*pi, nPhi+1);
% convert to cartesian coordinates
sintheta = sin(theta);
x = xc + cos(phi')*sintheta*r;
y = yc + sin(phi')*sintheta*r;
z = zc + ones(length(phi),1)*cos(theta)*r;
% Process output
if nargout == 0
% no output: draw the sphere
surf(hAx, x, y, z, options{:});
elseif nargout == 1
% one output: compute
varargout{1} = surf(hAx, x, y, z, options{:});
elseif nargout == 3
varargout{1} = x;
varargout{2} = y;
varargout{3} = z;
end
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