Add a useful package (from Source forge) for octave

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

diff --git a/octave_packages/nurbs-1.3.6/nrbtransp.m b/octave_packages/nurbs-1.3.6/nrbtransp.m
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+++ b/octave_packages/nurbs-1.3.6/nrbtransp.m
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+function tsrf = nrbtransp(srf)
+% 
+% NRBTRANSP: Transpose a NURBS surface, by swapping U and V directions.
+% 
+% Calling Sequence:
+% 
+%   tsrf = nrbtransp(srf)
+%
+% INPUT:
+% 
+%   srf                : NURBS surface, see nrbmak.
+%
+% OUTPUT:
+% 
+%   tsrf       : NURBS surface with U and V diretions transposed.
+% 
+% Description:
+% 
+%   Utility function that transposes a NURBS surface, by swapping U and
+%   V directions. NURBS curves cannot be transposed.
+%
+%    Copyright (C) 2000 Mark Spink
+%
+%    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 ~iscell(srf.knots)
+  error(' A NURBS curve cannot be transposed.');
+elseif size(srf.knots,2) == 3
+  error('The transposition of NURBS volumes has not been implemented.');
+end  
+
+tsrf = nrbmak(permute(srf.coefs,[1 3 2]), fliplr(srf.knots));
+
+end
+
+%!demo
+%! srf = nrb4surf([0 0 0], [1 0 1], [0 1 1], [1 1 2]);
+%! nrbplot(srf,[20 5]);
+%! title('Plane surface and its transposed (translated)')
+%! hold on
+%! srf.coefs(3,:,:) = srf.coefs(3,:,:) + 10;
+%! srf = nrbtransp(srf);
+%! nrbplot(srf,[20 5]);
+%! hold off
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