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

diff --git a/octave_packages/nurbs-1.3.6/nrbnumbasisfun.m b/octave_packages/nurbs-1.3.6/nrbnumbasisfun.m
new file mode 100644 (file)
index 0000000..22e692a
--- /dev/null
+++ b/octave_packages/nurbs-1.3.6/nrbnumbasisfun.m
@@ -0,0 +1,87 @@
+function idx = nrbnumbasisfun (points, nrb)
+%
+% NRBNUMBASISFUN:  Numbering of basis functions for NURBS
+%
+% Calling Sequence:
+% 
+%   N      = nrbnumbasisfun (u, crv)
+%   N      = nrbnumbasisfun ({u, v}, srf)
+%   N      = nrbnumbasisfun (p, srf)
+%
+%    INPUT:
+%   
+%      u or p(1,:,:)  - parametric points along u direction
+%      v or p(2,:,:)  - parametric points along v direction
+%      crv - NURBS curve
+%      srf - NURBS surface
+%   
+%    OUTPUT:
+%
+%      N - Indices of the basis functions that are nonvanishing at each
+%          point. size(N) == size(B)
+%
+%    Copyright (C) 2009 Carlo de Falco
+%
+%    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) ...
+      || (nargout>1) ...
+      || (~isstruct(nrb)) ...
+      || (iscell(points) && ~iscell(nrb.knots)) ...
+      || (~iscell(points) && iscell(nrb.knots) && (size(points,1)~=2)) ...
+      )
+    error('Incorrect input arguments in nrbnumbasisfun');
+  end
+
+
+  if (~iscell(nrb.knots))          %% NURBS curve
+    
+    iv  = findspan (nrb.number-1, nrb.order-1, points, nrb.knots);
+    idx = numbasisfun (iv, points, nrb.order-1, nrb.knots);
+    
+  elseif size(nrb.knots,2) == 2  %% NURBS surface
+
+    if (iscell(points))
+      [v, u] = meshgrid(points{2}, points{1});
+      p(1,:,:) = u;
+      p(2,:,:) = v;
+      p = reshape(p, 2, []);
+    else
+      p = points;
+    end
+    
+    idx = nrb_srf_numbasisfun__ (p, nrb); 
+  else
+    error('The function nrbnumbasisfun is not yet ready for volumes')      
+  end
+  
+end
+
+
+%!test
+%! p = 2;   q = 3;   m = 4; n = 5;
+%! Lx  = 1; Ly  = 1; 
+%! nrb = nrb4surf   ([0 0], [1 0], [0 1], [1 1]);
+%! nrb = nrbdegelev (nrb, [p-1, q-1]);
+%! ikx = linspace(0,1,m); iky = linspace(0,1,n);
+%! nrb = nrbkntins  (nrb, {ikx(2:end-1), iky(2:end-1)});
+%! nrb.coefs (4,:,:) = nrb.coefs (4,:,:) + rand (size (nrb.coefs (4,:,:)));
+%! u = rand (1, 30); v = rand (1, 10);
+%! u = (u-min (u))/max (u-min (u));
+%! v = (v-min (v))/max (v-min (v));
+%! N = nrbnumbasisfun ({u, v}, nrb);
+%! assert (all (all (N>0)), true)
+%! assert (all (all (N <= prod (nrb.number))), true)
+%! assert (max (max (N)), prod (nrb.number))
+%! assert (min (min (N)), 1)
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