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1 /* Copyright (C) 2009 Carlo de Falco |
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2 |
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3 This program is free software: you can redistribute it and/or modify |
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4 it under the terms of the GNU General Public License as published by |
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5 the Free Software Foundation, either version 3 of the License, or |
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6 (at your option) any later version. |
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7 |
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8 This program is distributed in the hope that it will be useful, |
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9 but WITHOUT ANY WARRANTY; without even the implied warranty of |
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10 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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11 GNU General Public License for more details. |
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12 |
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13 You should have received a copy of the GNU General Public License |
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14 along with this program. If not, see <http://www.gnu.org/licenses/>. |
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15 */ |
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16 |
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17 #include <octave/oct.h> |
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18 #include "low_level_functions.h" |
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19 |
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20 DEFUN_DLD(basisfun, args, nargout, "\n\ |
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21 BASISFUN: Compute B-Spline Basis Functions \n\ |
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22 \n\ |
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23 Calling Sequence:\n\ |
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24 \n\ |
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25 N = basisfun(iv,uv,p,U)\n\ |
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26 \n\ |
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27 INPUT:\n\ |
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28 \n\ |
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29 iv - knot span ( from FindSpan() )\n\ |
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30 uv - parametric point\n\ |
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31 p - spline degree\n\ |
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32 U - knot sequence\n\ |
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33 \n\ |
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34 OUTPUT:\n\ |
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35 \n\ |
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36 N - Basis functions vector(numel(uv)*(p+1))\n\ |
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37 \n\ |
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38 Algorithm A2.2 from 'The NURBS BOOK' pg70.\n\ |
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39 \n\ |
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40 ") |
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41 { |
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42 |
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43 octave_value_list retval; |
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44 const NDArray i = args(0).array_value(); |
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45 const NDArray u = args(1).array_value(); |
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46 int p = args(2).idx_type_value(); |
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47 const RowVector U = args(3).row_vector_value(); |
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48 RowVector N(p+1, 0.0); |
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49 Matrix B(u.numel (), p+1, 0.0); |
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50 |
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51 if (!error_state) |
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52 { |
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53 for (octave_idx_type ii(0); ii < u.numel (); ii++) |
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54 { |
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55 basisfun(int(i(ii)), u(ii), p, U, N); |
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56 B.insert(N, ii, 0); |
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57 } |
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58 |
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59 retval(0) = octave_value(B); |
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60 } |
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61 return retval; |
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62 } |
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63 |
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64 /* |
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65 %!shared n, U, p, u, s |
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66 %!test |
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67 %! n = 3; |
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68 %! U = [0 0 0 1/2 1 1 1]; |
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69 %! p = 2; |
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70 %! u = linspace(0, 1, 10); |
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71 %! s = findspan(n, p, u, U); |
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72 %! assert (s, [2*ones(1, 5) 3*ones(1, 5)]); |
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73 %!test |
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74 %! Bref = [1.00000 0.00000 0.00000 |
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75 %! 0.60494 0.37037 0.02469 |
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76 %! 0.30864 0.59259 0.09877 |
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77 %! 0.11111 0.66667 0.22222 |
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78 %! 0.01235 0.59259 0.39506 |
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79 %! 0.39506 0.59259 0.01235 |
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80 %! 0.22222 0.66667 0.11111 |
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81 %! 0.09877 0.59259 0.30864 |
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82 %! 0.02469 0.37037 0.60494 |
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83 %! 0.00000 0.00000 1.00000]; |
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84 %! B = basisfun(s, u, p, U); |
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85 %! assert (B, Bref, 1e-5); |
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86 */ |
