rpy2r.m

%RPY2R Roll-pitch-yaw angles to SO(3) rotation matrix
%
% R = RPY2R(ROLL, PITCH, YAW, OPTIONS) is an SO(3) orthonornal rotation
% matrix (3x3) equivalent to the specified roll, pitch, yaw angles angles.
% These correspond to rotations about the Z, Y, X axes respectively. If
% ROLL, PITCH, YAW are column vectors (Nx1) then they are assumed to
% represent a trajectory and R is a three-dimensional matrix (3x3xN), where
% the last index corresponds to rows of ROLL, PITCH, YAW.
%
% R = RPY2R(RPY, OPTIONS) as above but the roll, pitch, yaw angles are
% taken from the vector (1x3) RPY=[ROLL,PITCH,YAW]. If RPY is a matrix
% (Nx3) then R is a three-dimensional matrix (3x3xN), where the last index
% corresponds to rows of RPY which are assumed to be [ROLL,PITCH,YAW].
%
% Options::
%  'deg'      Compute angles in degrees (radians default)
%  'xyz'      Rotations about X, Y, Z axes (for a robot gripper)
%  'zyx'      Rotations about Z, Y, X axes (for a mobile robot, default)
%  'yxz'      Rotations about Y, X, Z axes (for a camera)
%  'arm'      Rotations about X, Y, Z axes (for a robot arm)
%  'vehicle'  Rotations about Z, Y, X axes (for a mobile robot)
%  'camera'   Rotations about Y, X, Z axes (for a camera)
%
% Note::
% - Toolbox rel 8-9 has XYZ angle sequence as default.
% - ZYX order is appropriate for vehicles with direction of travel in the X
%   direction.  XYZ order is appropriate if direction of travel is in the Z
%   direction.
% - 'arm', 'vehicle', 'camera' are synonyms for 'xyz', 'zyx' and 'yxz'
%   respectively.
%
% See also TR2RPY, EUL2TR.

% Copyright (C) 1993-2019 Peter I. Corke
%
% This file is part of The Spatial Math Toolbox for MATLAB (SMTB).
% 
% Permission is hereby granted, free of charge, to any person obtaining a copy
% of this software and associated documentation files (the "Software"), to deal
% in the Software without restriction, including without limitation the rights
% to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
% of the Software, and to permit persons to whom the Software is furnished to do
% so, subject to the following conditions:
%
% The above copyright notice and this permission notice shall be included in all
% copies or substantial portions of the Software.
%
% THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
% IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
% FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
% COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
% IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
% CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
%
% https://github.com/petercorke/spatial-math

function R = rpy2r(roll, varargin)
    opt.order = {'zyx', 'xyz', 'yxz', 'arm', 'vehicle', 'camera'};
    opt.deg = false;
    [opt,args] = tb_optparse(opt, varargin);
    
    % unpack the arguments
    if numcols(roll) == 3
		pitch = roll(:,2);
		yaw = roll(:,3);
		roll = roll(:,1);
	elseif nargin >= 3
        pitch = args{1};
        yaw = args{2};
    else
        error('SMTB:rpy2r:badarg', 'bad arguments')
    end

    % optionally convert from degrees
    if opt.deg
        d2r = pi/180.0;
        roll = roll * d2r;
        pitch = pitch * d2r;
        yaw = yaw * d2r;
    end

    switch opt.order
        case {'xyz', 'arm'}
            % XYZ order
            if numrows(roll) == 1
                R = rotx(yaw) * roty(pitch) * rotz(roll);
            else
                R = zeros(3,3,numrows(roll));
                for i=1:numrows(roll)
                    R(:,:,i) = rotx(yaw(i)) * roty(pitch(i)) * rotz(roll(i));
                end
            end
        case {'zyx', 'vehicle'}
            % ZYX order
            if numrows(roll) == 1
                R = rotz(yaw) * roty(pitch) * rotx(roll);
            else
                R = zeros(3,3,numrows(roll));
                for i=1:numrows(roll)
                    R(:,:,i) = rotz(yaw(i)) * roty(pitch(i)) * rotx(roll(i));
                end
            end
            
        case {'yxz', 'camera'}
            % YXZ order
            if numrows(roll) == 1
                R = roty(yaw) * rotx(pitch) * rotz(roll);
            else
                R = zeros(3,3,numrows(roll));
                for i=1:numrows(roll)
                    R(:,:,i) = roty(yaw(i)) * rotx(pitch(i)) * rotz(roll(i));
                end
            end
    end
end