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

createScaling3d(varargin)
```function trans = createScaling3d(varargin)
%CREATESCALING3D Create the 4x4 matrix of a 3D scaling
%
%   TRANS = createScaling3d(S);
%   returns the scaling transform corresponding to a scaling factor S in
%   each direction. S can be a scalar, or a 1x3 vector containing the
%   scaling factor in each direction.
%
%   TRANS = createScaling3d(SX, SY, SZ);
%   returns the scaling transform corresponding to a different scaling
%   factor in each direction.
%
%   The returned matrix has the form :
%   [SX  0  0  0]
%   [ 0 SY  0  0]
%   [ 0  0 SZ  0]
%   [ 0  0  0  0]
%
%   transforms3d, transformPoint3d, transformVector3d, createTranslation3d,
%   createRotationOx, createRotationOy, createRotationOz
%
%   ---------
%   author : David Legland
%   INRA - TPV URPOI - BIA IMASTE
%   created the 20/04/2006.
%

%   HISTORY
%   25/11/2008 rename from scale3d to scaling3d
%   30/04/2009 rename to createScaling3d

% process input parameters
if isempty(varargin)
% assert uniform scaling in each direction
sx = 1;
sy = 1;
sz = 1;
elseif length(varargin)==1
% only one argument
var = varargin{1};
if length(var)==1
% same scaling factor in each direction
sx = var;
sy = var;
sz = var;
elseif length(var)==3
% scaling is a vector, giving different scaling in each direction
sx = var(1);
sy = var(2);
sz = var(3);
else
error('wrong size for first parameter of "createScaling3d"');
end
elseif length(varargin)==3
% 3 arguments, giving scaling in each direction
sx = varargin{1};
sy = varargin{2};
sz = varargin{3};
else
error('wrong number of arguments for "createScaling3d"');
end

% create the scaling matrix
trans = [sx 0 0 0;0 sy 0 0;0 0 sz 0;0 0 0 1];

```