transformPoint

TRANSFORMPOINT Apply an affine transform to a point or a point set.

   PT2 = transformPoint(PT1, TRANSFO);
   Returns the result of the transformation TRANSFO applied to the point
   PT1. PT1 has the form [xp yp], and TRANSFO is either a 2-by-2, a
   2-by-3, or a 3-by-3 matrix, 

   Format of TRANSFO can be one of :
   [a b]   ,   [a b c] , or [a b c]
   [d e]       [d e f]      [d e f]
                            [0 0 1]

   PT2 = transformPoint(PT1, TRANSFO);
   Also works when PTA is a N-by-2 array representing point coordinates.
   In this case, the result PT2 has the same size as PT1.

   [X2, Y2] = transformPoint(X1, Y1, TRANS);
   Also works when PX1 and PY1 are two arrays the same size. The function
   transforms each pair (PX1, PY1), and returns the result in (X2, Y2),
   which has the same size as (PX1 PY1). 


   See also
     points2d, transforms2d, translation, rotation

0001 function varargout = transformPoint(varargin)
0002 %TRANSFORMPOINT Apply an affine transform to a point or a point set.
0003 %
0004 %   PT2 = transformPoint(PT1, TRANSFO);
0005 %   Returns the result of the transformation TRANSFO applied to the point
0006 %   PT1. PT1 has the form [xp yp], and TRANSFO is either a 2-by-2, a
0007 %   2-by-3, or a 3-by-3 matrix,
0008 %
0009 %   Format of TRANSFO can be one of :
0010 %   [a b]   ,   [a b c] , or [a b c]
0011 %   [d e]       [d e f]      [d e f]
0012 %                            [0 0 1]
0013 %
0014 %   PT2 = transformPoint(PT1, TRANSFO);
0015 %   Also works when PTA is a N-by-2 array representing point coordinates.
0016 %   In this case, the result PT2 has the same size as PT1.
0017 %
0018 %   [X2, Y2] = transformPoint(X1, Y1, TRANS);
0019 %   Also works when PX1 and PY1 are two arrays the same size. The function
0020 %   transforms each pair (PX1, PY1), and returns the result in (X2, Y2),
0021 %   which has the same size as (PX1 PY1).
0022 %
0023 %
0024 %   See also
0025 %     points2d, transforms2d, translation, rotation
0026 %
0027 
0028 % ------
0029 % Author: David Legland
0030 % E-mail: david.legland@inrae.fr
0031 % Created: 2004-04-06
0032 % Copyright 2004-2024 INRA - TPV URPOI - BIA IMASTE
0033 
0034 % parse input arguments
0035 if length(varargin) == 2
0036     var = varargin{1};
0037     px = var(:,1);
0038     py = var(:,2);
0039     trans = varargin{2};
0040 elseif length(varargin) == 3
0041     px = varargin{1};
0042     py = varargin{2};
0043     trans = varargin{3};
0044 else
0045     error('wrong number of arguments in "transformPoint"');
0046 end
0047 
0048 
0049 % apply linear part of the transform
0050 px2 = px * trans(1,1) + py * trans(1,2);
0051 py2 = px * trans(2,1) + py * trans(2,2);
0052 
0053 % add translation vector, if exist
0054 if size(trans, 2) > 2
0055     px2 = px2 + trans(1,3);
0056     py2 = py2 + trans(2,3);
0057 end
0058 
0059 % format output arguments
0060 if nargout < 2
0061     varargout{1} = [px2 py2];
0062 elseif nargout
0063     varargout{1} = px2;
0064     varargout{2} = py2;
0065 end