src/libengrid/optimisenormalvector.cpp

   1 // ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
   2 // +                                                                      +
   3 // + This file is part of enGrid.                                         +
   4 // +                                                                      +
   5 // + Copyright 2008-2014 enGits GmbH                                      +
   6 // +                                                                      +
   7 // + enGrid is free software: you can redistribute it and/or modify       +
   8 // + it under the terms of the GNU General Public License as published by +
   9 // + the Free Software Foundation, either version 3 of the License, or    +
  10 // + (at your option) any later version.                                  +
  11 // +                                                                      +
  12 // + enGrid is distributed in the hope that it will be useful,            +
  13 // + but WITHOUT ANY WARRANTY; without even the implied warranty of       +
  14 // + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the        +
  15 // + GNU General Public License for more details.                         +
  16 // +                                                                      +
  17 // + You should have received a copy of the GNU General Public License    +
  18 // + along with enGrid. If not, see <http://www.gnu.org/licenses/>.       +
  19 // +                                                                      +
  20 // ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
  21
  22 #include "optimisenormalvector.h"
  23 #include "geometrytools.h"
  24
  25 OptimiseNormalVector::OptimiseNormalVector(bool use_grouping, double grouping_angle)
  26 {
  27   m_UseGrouping = use_grouping;
  28   m_GroupingAngle = grouping_angle;
  29 }
  30
  31 void OptimiseNormalVector::addConstraint(vec3_t n)
  32 {
  33   m_Constraints.append(n);
  34 }
  35
  36 void OptimiseNormalVector::addFace(vec3_t n)
  37 {
  38   if (m_UseGrouping) {
  39     bool found = false;
  40     foreach (vec3_t nf, m_Faces) {
  41       if (GeometryTools::angle(n, nf) < m_GroupingAngle) {
  42         found = true;
  43         break;
  44       }
  45     }
  46     if (!found) {
  47       m_Faces.append(n);
  48     }
  49   } else {
  50     m_Faces.append(n);
  51   }
  52 }
  53
  54 double OptimiseNormalVector::func(vec3_t n)
  55 {
  56   double hf_min =  1;
  57   double hf_max = -1;
  58   double hc = 0;
  59   vec3_t n0 = n;
  60   n0.normalise();
  61   double err = 0;
  62   foreach (vec3_t nc, m_Constraints) {
  63     nc.normalise();
  64     double h = nc*n0;
  65     hc = max(h, fabs(hc));
  66   }
  67   foreach (vec3_t nf, m_Faces) {
  68     nf.normalise();
  69     double h = nf*n0;
  70     hf_min = min(h, hf_min);
  71     hf_max = max(h, hf_max);
  72     err += sqr(1 - h);
  73   }
  74   if (m_UseGrouping) {
  75     err += sqr(hc);
  76   } else {
  77     err = sqr(hc) + sqr(1 - hf_min) + sqr(1 - hf_max);
  78   }
  79   return err;
  80 }
  81
  82 vec3_t OptimiseNormalVector::optimise(vec3_t n)
  83 {
  84   int count = 0;
  85   computeDerivatives(n);
  86   n.normalise();
  87   double scale = 0.1;
  88   while (count < 100 && scale > 1e-4) {
  89     double err1 = func(n);
  90     vec3_t dn = -1.0*grad_f;
  91     dn -= (n*dn)*n;
  92     if (grad_f.abs() > 1e-10) {
  93       dn.normalise();
  94     }
  95     double relax = min(scale, scale*grad_f.abs());
  96     dn *= relax;
  97     vec3_t n_old = n;
  98     n += dn;
  99     n.normalise();
 100     double err2 = func(n);
 101     if (err2 > err1) {
 102       scale *= 0.1;
 103       n = n_old;
 104     }
 105     ++count;
 106     computeDerivatives(n);
 107   }
 108   return n;
 109 }
 110
 111 vec3_t OptimiseNormalVector::operator()(vec3_t n)
 112 {
 113   vec3_t n_opt = optimise(n);
 114   if (!checkVector(n_opt)) {
 115     n_opt = n;
 116   }
 117   n_opt.normalise();
 118   return n_opt;
 119 }