Code covered by the BSD License

# geom3d

### David Legland (view profile)

19 Jun 2009 (Updated )

Library to handle 3D geometric primitives: create, intersect, display, and make basic computations

### Editor's Notes:

This file was selected as MATLAB Central Pick of the Week

createRotationOx(varargin)
```function trans = createRotationOx(varargin)
%CREATEROTATIONOX Create the 4x4 matrix of a 3D rotation around x-axis
%
%   TRANS = createRotationOx(THETA);
%   Returns the transform matrix corresponding to a rotation by the angle
%   THETA (in radians) around the Ox axis. A rotation by an angle of PI/2
%   would transform the vector [0 1 0] into the vector [0 0 1].
%
%   The returned matrix has the form:
%   [1      0            0      0]
%   [0  cos(THETA) -sin(THETA)  0]
%   [0  sin(THETA)  cos(THETA)  0]
%   [0      0            0      1]
%
%   TRANS = createRotationOx(ORIGIN, THETA);
%   TRANS = createRotationOx(X0, Y0, Z0, THETA);
%   Also specifies origin of rotation. The result is similar as performing
%   translation(-X0, -Y0, -Z0), rotation, and translation(X0, Y0, Z0).
%
%   transforms3d, transformPoint3d, createRotationOy, createRotationOz
%
%   ---------
%   author : David Legland
%   INRA - TPV URPOI - BIA IMASTE
%   created the 18/02/2005.
%

%   HISTORY
%   24/11/2008 changed convention for angle
%   22/04/2009 rename as createRotationOx

% default values
dx = 0;
dy = 0;
dz = 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};
dx = var(1);
dy = var(2);
dz = var(3);
theta = varargin{2};
elseif length(varargin)==3
% origin (x and y) and angle
dx = varargin{1};
dy = varargin{2};
dz = varargin{3};
theta = varargin{3};
end

% compute coefs
cot = cos(theta);
sit = sin(theta);

% create transformation
trans = [...
1 0 0 0;...
0 cot -sit 0;...
0 sit cot 0;...
0 0 0 1];