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%TRANSL Create translational transform
%
% T = TRANSL(X, Y, Z) is a homogeneous transform representing a
% pure translation.
%
% T = TRANSL(P) is a homogeneous transform representing a translation or
% point P=[X,Y,Z]. If P (Mx3) it represents a sequence and T (4x4xM)
% is a sequence of homogenous transforms such that T(:,:,i) corresponds to
% the i'th row of P.
%
% P = TRANSL(T) is the translational part of a homogenous transform as a
% 3-element column vector. If T (4x4xM) is a homgoeneous transform sequence
% the rows of P (Mx3) are the translational component of the corresponding
% transform in the sequence.
%
% Notes::
% - Somewhat unusually this function performs a function and its inverse. An
% historical anomaly.
%
% See also CTRAJ.
% Copyright (C) 1993-2011, by Peter I. Corke
%
% This file is part of The Robotics Toolbox for Matlab (RTB).
%
% RTB is free software: you can redistribute it and/or modify
% it under the terms of the GNU Lesser General Public License as published by
% the Free Software Foundation, either version 3 of the License, or
% (at your option) any later version.
%
% RTB is distributed in the hope that it will be useful,
% but WITHOUT ANY WARRANTY; without even the implied warranty of
% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
% GNU Lesser General Public License for more details.
%
% You should have received a copy of the GNU Leser General Public License
% along with RTB. If not, see <http://www.gnu.org/licenses/>.
function T = transl(x, y, z)
if nargin == 1
if ishomog(x)
if ndims(x) == 3
% transl(T) -> P, trajectory case
T = squeeze(x(1:3,4,:))';
else
% transl(T) -> P
T = x(1:3,4);
end
elseif all(size(x) == [3 3])
T = x(1:2,3);
elseif length(x) == 2
% transl(P) -> T
t = x(:);
T = [eye(2) t(:);
0 0 1];
elseif length(x) == 3
% transl(P) -> T
t = x(:);
T = [eye(3) t(:);
0 0 0 1];
else
% transl(P) -> T, trajectory case
n = numrows(x);
T = repmat(eye(4,4), [1 1 n]);
T(1:3,4,:) = x';
end
elseif nargin == 2
% transl(x,y) -> T
t = [x; y];
T = rt2tr( eye(2), t);
elseif nargin == 3
% transl(x,y,z) -> T
t = [x; y; z];
T = rt2tr( eye(3), t);
end