src/libengrid/optimisenormalvector.cpp

   1 //
   2 // ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
   3 // +                                                                      +
   4 // + This file is part of enGrid.                                         +
   5 // +                                                                      +
   6 // + Copyright 2008-2013 enGits GmbH                                      +
   7 // +                                                                      +
   8 // + enGrid is free software: you can redistribute it and/or modify       +
   9 // + it under the terms of the GNU General Public License as published by +
  10 // + the Free Software Foundation, either version 3 of the License, or    +
  11 // + (at your option) any later version.                                  +
  12 // +                                                                      +
  13 // + enGrid is distributed in the hope that it will be useful,            +
  14 // + but WITHOUT ANY WARRANTY; without even the implied warranty of       +
  15 // + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the        +
  16 // + GNU General Public License for more details.                         +
  17 // +                                                                      +
  18 // + You should have received a copy of the GNU General Public License    +
  19 // + along with enGrid. If not, see <http://www.gnu.org/licenses/>.       +
  20 // +                                                                      +
  21 // ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
  22 //
  23 #include "optimisenormalvector.h"
  24
  25 void OptimiseNormalVector::addConstraint(vec3_t n)
  26 {
  27   m_Constraints.append(n);
  28 }
  29
  30 void OptimiseNormalVector::addFace(vec3_t n)
  31 {
  32   m_Faces.append(n);
  33 }
  34
  35 double OptimiseNormalVector::func(vec3_t n)
  36 {
  37   double hf = 1;
  38   double hc = 0;
  39   vec3_t n0 = n;
  40   n0.normalise();
  41   foreach (vec3_t nc, m_Constraints) {
  42     nc.normalise();
  43     double h = nc*n0;
  44     hc = max(h, fabs(hc));
  45   }
  46   foreach (vec3_t nf, m_Faces) {
  47     nf.normalise();
  48     double h = nf*n0;
  49     hf = min(h, hf);
  50   }
  51   return sqr(hc) + sqr(1 - hf);
  52 }
  53
  54 vec3_t OptimiseNormalVector::optimise(vec3_t n)
  55 {
  56   int count = 0;
  57   computeDerivatives(n);
  58   n.normalise();
  59   double scale = 1;
  60   while (count < 100 && scale > 2e-4) {
  61     double ag = grad_f.abs();
  62     double err1 = func(n);
  63     vec3_t dn = -1.0*grad_f;
  64     dn -= (n*dn)*n;
  65     if (grad_f.abs() > 1e-10) {
  66       dn.normalise();
  67     }
  68     double relax = min(scale, scale*grad_f.abs());
  69     dn *= relax;
  70     n += dn;
  71     n.normalise();
  72     double err2 = func(n);
  73     if (err2 > err1) {
  74       scale *= 0.1;
  75     }
  76     ++count;
  77     computeDerivatives(n);
  78   }
  79   return n;
  80 }
  81
  82 vec3_t OptimiseNormalVector::operator()(vec3_t n)
  83 {
  84   vec3_t n_opt = optimise(n);
  85   if (!checkVector(n_opt)) {
  86     n_opt = n;
  87   }
  88   n_opt.normalise();
  89   return n_opt;
  90 }