Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / nurbs-1.3.6 / nrbextrude.m

diff --git a/octave_packages/nurbs-1.3.6/nrbextrude.m b/octave_packages/nurbs-1.3.6/nrbextrude.m
new file mode 100644 (file)
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+++ b/octave_packages/nurbs-1.3.6/nrbextrude.m
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+function srf = nrbextrude(curve,vector)
+
+%
+% NRBEXTRUDE: Construct a NURBS surface by extruding a NURBS curve, or 
+%  construct a NURBS volume by extruding a NURBS surface.
+% 
+% Calling Sequence:
+% 
+%   srf = nrbextrude(crv,vec);
+% 
+% INPUT:
+% 
+%   crv                : NURBS curve or surface to extrude, see nrbmak.
+% 
+%   vec                : Vector along which the entity is extruded.
+%
+% OUTPUT: 
+% 
+%   srf                : NURBS surface or volume constructed.
+% 
+% Description:
+% 
+%   Constructs either a NURBS surface by extruding a NURBS curve along a  
+%   defined vector, or a NURBS volume by extruding a NURBS surface. In the 
+%   first case, the NURBS curve forms the U direction of the surface edge, and
+%   is extruded along the vector in the V direction. In the second case, the 
+%   original surface forms the U and V direction of the volume, and is extruded
+%   along the W direction.
+%
+% Examples:
+% 
+%   Form a hollow cylinder by extruding a circle along the z-axis.
+%
+%   srf = nrbextrude(nrbcirc, [0,0,1]);
+%
+%    Copyright (C) 2000 Mark Spink
+%    Copyright (C) 2010 Rafael Vazquez
+%
+%    This program is free software: you can redistribute it and/or modify
+%    it under the terms of the GNU General Public License as published by
+%    the Free Software Foundation, either version 2 of the License, or
+%    (at your option) any later version.
+
+%    This program 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 General Public License for more details.
+%
+%    You should have received a copy of the GNU General Public License
+%    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+if (nargin < 2)
+  error('Error too few input arguments!');
+end
+
+if (iscell (curve.knots))
+  if (numel (curve.knots) == 3)
+    error('Nurbs volumes cannot be extruded!');
+  end
+  for ii = 1:size(curve.coefs,3)
+    coefs(:,:,ii) = vectrans(vector) * squeeze (curve.coefs(:,:,ii));
+  end
+  coefs = cat(4,curve.coefs,coefs);
+  srf = nrbmak(coefs,{curve.knots{:}, [0 0 1 1]});
+else
+  coefs = cat(3,curve.coefs,vectrans(vector)*curve.coefs);
+  srf = nrbmak(coefs,{curve.knots, [0 0 1 1]});
+end
+
+end
+
+%!demo
+%! crv = nrbtestcrv;
+%! srf = nrbextrude(crv,[0 0 5]);
+%! nrbplot(srf,[40 10]);
+%! title('Extrusion of a test curve along the z-axis');
+%! hold off
+%
+%!demo
+%! crv1 = nrbcirc (1, [0 0], 0, pi/2);
+%! crv2 = nrbcirc (2, [0 0], 0, pi/2);
+%! srf  = nrbruled (crv1, crv2);
+%! vol  = nrbextrude (srf, [0 0 1]);
+%! nrbplot (vol, [30 10 10])
+%! title ('Extrusion of the quarter of a ring')
+%
+%!demo
+%! srf = nrbtestsrf;
+%! vol = nrbextrude(srf, [0 0 10]);
+%! nrbplot(vol,[20 20 20]);
+%! title('Extrusion of a test surface along the z-axis');
+%! hold off