src/libengrid/polyline.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 "polyline.h"
  23
  24 void PolyLine::getStencil(double l, int &i1, int &i2, double &w1, double &w2)
  25 {
  26   l *= m_Length;
  27   double L = 0;
  28   w2 = 1;
  29   i1 = m_Points.size() - 2;
  30   i2 = m_Points.size() - 1;
  31   for (int i = 1; i < m_Points.size(); ++i) {
  32     double dL = (m_Points[i] - m_Points[i-1]).abs();
  33     if (l >= L && l <= L + dL) {
  34       i1 = i - 1;
  35       i2 = i;
  36       w2 = (l - L)/dL;
  37       break;
  38     }
  39     L += dL;
  40   }
  41   w1 = 1 - w2;
  42 }
  43
  44 vec3_t PolyLine::position(double l)
  45 {
  46   int i1, i2;
  47   double w1, w2;
  48   getStencil(l, i1, i2, w1, w2);
  49   return w1*m_Points[i1] + w2*m_Points[i2];
  50 }
  51
  52 vec3_t PolyLine::normal(double l)
  53 {
  54   int i1, i2;
  55   double w1, w2;
  56   getStencil(l, i1, i2, w1, w2);
  57   vec3_t n = m_Points[i2] - m_Points[i1];
  58   n.normalise();
  59   return n;
  60 }
  61
  62 vec3_t PolyLine::intersection(vec3_t x, vec3_t n)
  63 {
  64   double min_err = EG_LARGE_REAL;
  65   vec3_t x_best = x;
  66   for (int i = 1; i < m_Points.size(); ++i) {
  67     double k = GeometryTools::intersection(m_Points[i-1], m_Points[i] - m_Points[i-1], x, n);
  68     double err = fabs(k - 0.5);
  69     if (err < min_err) {
  70       min_err = err;
  71       x_best = (1-k)*m_Points[i-1] + k*m_Points[i];
  72     }
  73   }
  74   return x_best;
  75 }