/usr/share/octave/packages/nurbs-1.3.10/nrbextrude.m is in octave-nurbs 1.3.10-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 | 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 3 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
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