transformVector

TRANSFORMVECTOR Transform a vector with an affine transform.

   VECT2 = transformVector(VECT1, TRANS);
   where VECT1 has the form [xv yv], and TRANS is a [2*2], [2*3] or [3*3]
   matrix, returns the vector transformed with affine transform TRANS.

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

   VECT2 = transformVector(VECT1, TRANS);
   Also works when PTA is a [N*2] array of double. In this case, VECT2 has
   the same size as VECT1.

   [vx2 vy2] = transformVector(vx1, vy1, TRANS);
   Also works when vx1 and vy1 are arrays the same size. The function
   transform each couple of (vx1, vy1), and return the result in 
   (vx2, vy2), which is the same size as (vx1 vy1).


   See also:
   vectors2d, transforms2d, rotateVector, transformPoint

   ---------

   author : David Legland
   INRA - TPV URPOI - BIA IMASTE
   created the 12/03/2007.

0001 function varargout = transformVector(varargin)
0002 %TRANSFORMVECTOR Transform a vector with an affine transform.
0003 %
0004 %   VECT2 = transformVector(VECT1, TRANS);
0005 %   where VECT1 has the form [xv yv], and TRANS is a [2*2], [2*3] or [3*3]
0006 %   matrix, returns the vector transformed with affine transform TRANS.
0007 %
0008 %   Format of TRANS can be one of :
0009 %   [a b]   ,   [a b c] , or [a b c]
0010 %   [d e]       [d e f]      [d e f]
0011 %                            [0 0 1]
0012 %
0013 %   VECT2 = transformVector(VECT1, TRANS);
0014 %   Also works when PTA is a [N*2] array of double. In this case, VECT2 has
0015 %   the same size as VECT1.
0016 %
0017 %   [vx2 vy2] = transformVector(vx1, vy1, TRANS);
0018 %   Also works when vx1 and vy1 are arrays the same size. The function
0019 %   transform each couple of (vx1, vy1), and return the result in
0020 %   (vx2, vy2), which is the same size as (vx1 vy1).
0021 %
0022 %
0023 %   See also:
0024 %   vectors2d, transforms2d, rotateVector, transformPoint
0025 %
0026 %   ---------
0027 %
0028 %   author : David Legland
0029 %   INRA - TPV URPOI - BIA IMASTE
0030 %   created the 12/03/2007.
0031 %
0032 
0033 %   HISTORY
0034 
0035 
0036 if length(varargin)==2
0037     var = varargin{1};
0038     vx = var(:,1);
0039     vy = var(:,2);
0040     trans = varargin{2};
0041 elseif length(varargin)==3
0042     vx = varargin{1};
0043     vy = varargin{2};
0044     trans = varargin{3};
0045 else
0046     error('wrong number of arguments in "transformVector"');
0047 end
0048 
0049 
0050 % compute new position of vector
0051 vx2 = vx*trans(1,1) + vy*trans(1,2);
0052 vy2 = vx*trans(2,1) + vy*trans(2,2);
0053 
0054 % format output
0055 if nargout==0 || nargout==1
0056     varargout{1} = [vx2 vy2];
0057 elseif nargout==2
0058     varargout{1} = vx2;
0059     varargout{2} = vy2;
0060 end