/usr/share/octave/packages/nurbs-1.3.7/nrbextract.m is in octave-nurbs 1.3.7-1build1.
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 | function crvs = nrbextract(srf)
%
% NRBEXTRACT: construct NURBS curves by extracting the boundaries of a NURBS surface, or NURBS surfaces by extracting the boundary of a NURBS volume.
%
% Calling Sequence:
%
% crvs = nrbextract(surf);
%
% INPUT:
%
% surf : NURBS surface or volume, see nrbmak.
%
% OUTPUT:
%
% crvs : array of NURBS curves or NURBS surfaces extracted.
%
% Description:
%
% Constructs either an array of four NURBS curves, by extracting the boundaries
% of a NURBS surface, or an array of six surfaces, by extracting the boundaries
% of a NURBS volume. The new entities are ordered in the following way
%
% 1: U = 0
% 2: U = 1
% 3: V = 0
% 4: V = 1
% 5: W = 0 (only for volumes)
% 6: W = 1 (only for volumes)
%
% 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 (~iscell (srf.knots))
error('The boundary information is only extracted for NURBS surfaces or volumes');
end
if (numel (srf.knots) == 2)
for ind = 1:2
ind2 = mod (ind, 2) + 1; %ind2 = [2 1];
bnd1 = (ind - 1) * 2 + 1;
bnd2 = (ind - 1) * 2 + 2;
if (ind == 1)
coefs1 = squeeze (srf.coefs(:,1,:));
coefs2 = squeeze (srf.coefs(:,end,:));
elseif (ind == 2)
coefs1 = squeeze (srf.coefs(:,:,1));
coefs2 = squeeze (srf.coefs(:,:,end));
end
crvs(bnd1) = nrbmak (coefs1, srf.knots{ind2});
crvs(bnd2) = nrbmak (coefs2, srf.knots{ind2});
end
elseif (numel (srf.knots) == 3)
for ind = 1:3
inds = setdiff (1:3, ind);
bnd1 = (ind - 1) * 2 + 1;
bnd2 = (ind - 1) * 2 + 2;
if (ind == 1)
coefs1 = squeeze (srf.coefs(:,1,:,:));
coefs2 = squeeze (srf.coefs(:,end,:,:));
elseif (ind == 2)
coefs1 = squeeze (srf.coefs(:,:,1,:));
coefs2 = squeeze (srf.coefs(:,:,end,:));
elseif (ind == 3)
coefs1 = squeeze (srf.coefs(:,:,:,1));
coefs2 = squeeze (srf.coefs(:,:,:,end));
end
crvs(bnd1) = nrbmak (coefs1, {srf.knots{inds(1)} srf.knots{inds(2)}});
crvs(bnd2) = nrbmak (coefs2, {srf.knots{inds(1)} srf.knots{inds(2)}});
end
else
error ('The entity is not a surface nor a volume')
end
end
|