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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 trans = createRotation(varargin)
%CREATEROTATION Create the 3*3 matrix of a rotation.
%
% TRANS = createRotation(THETA);
% Returns the rotation corresponding to angle THETA (in radians)
% The returned matrix has the form :
% [cos(theta) -sin(theta) 0]
% [sin(theta) cos(theta) 0]
% [0 0 1]
%
% TRANS = createRotation(POINT, THETA);
% TRANS = createRotation(X0, Y0, THETA);
% Also specifies origin of rotation. The result is similar as performing
% translation(-X0, -Y0), rotation(THETA), and translation(X0, Y0).
%
% Example
% % apply a rotation on a polygon
% poly = [0 0; 30 0;30 10;10 10;10 20;0 20];
% trans = createRotation([10 20], pi/6);
% polyT = transformPoint(poly, trans);
% % display the original and the rotated polygons
% figure; hold on; axis equal; axis([-10 40 -10 40]);
% drawPolygon(poly, 'k');
% drawPolygon(polyT, 'b');
%
% See also
% transforms2d, transformPoint, createRotation90, createTranslation
%
% ------
% Author: David Legland
% E-mail: david.legland@inrae.fr
% Created: 2004-04-06
% Copyright 2004-2023 INRA - TPV URPOI - BIA IMASTE
% default values
cx = 0;
cy = 0;
theta = 0;
% get input values
if length(varargin)==1
% only angle
theta = varargin{1};
elseif length(varargin)==2
% origin point (as array) and angle
var = varargin{1};
cx = var(1);
cy = var(2);
theta = varargin{2};
elseif length(varargin)==3
% origin (x and y) and angle
cx = varargin{1};
cy = varargin{2};
theta = varargin{3};
end
% compute coefs
cot = cos(theta);
sit = sin(theta);
tx = cy*sit - cx*cot + cx;
ty = -cy*cot - cx*sit + cy;
% create transformation matrix
trans = [cot -sit tx; sit cot ty; 0 0 1];
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