simutils.cpp

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// g2o - General Graph Optimization
// Copyright (C) 2011 R. Kuemmerle, G. Grisetti, H. Strasdat, W. Burgard
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright notice,
//   this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above copyright
//   notice, this list of conditions and the following disclaimer in the
//   documentation and/or other materials provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
// IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
// TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
// PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
// TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
#include "simutils.h"
 
namespace g2o {
// -1: outside
// 0: p1Clipped
// 1: p2clipped
// 2: inside
// 3: all clipped
using namespace Eigen;
 
int clipSegmentCircle(Eigen::Vector2d& p1, Eigen::Vector2d& p2, double r) {
  double r2 = r * r;
  Eigen::Vector2d pBase = p1;
  Eigen::Vector2d dp = p2 - p1;
  double length = dp.norm();
  dp.normalize();
  double p = 2 * dp.dot(p1);
  double q = p1.squaredNorm() - r2;
  double disc = p * p - 4 * q;
 
  if (disc <= 0) {  // no intersection or single point intersection
    return -1;
  }
  disc = sqrt(disc);
 
  double t1 = .5 * (-p - disc);
  double t2 = .5 * (-p + disc);
 
  if (t1 > length || t2 < 0) return -1;  // no intersection
  bool clip1 = false;
  bool clip2 = false;
  if (t1 > 0) {
    p1 = pBase + dp * t1;
    clip1 = true;
  }
  if (t2 < length) {
    p2 = pBase + dp * t1;
    clip2 = true;
  }
  if (clip1)
    if (clip2)
      return 3;
    else
      return 0;
  else if (clip2)
    return 1;
  return 2;
}
 
// -1: outside
// 0: p1Clipped
// 1: p2clipped
// 2: inside
 
int clipSegmentLine(Eigen::Vector2d& p1, Eigen::Vector2d& p2, double a,
                    double b, double c) {
  bool p1inside = true;
  bool p2inside = true;
  if (a * p1.x() + b * p1.y() + c < 0) {
    p1inside = false;
  }
  if (a * p2.x() + b * p2.y() + c < 0) {
    p2inside = false;
  }
  if (p1inside && p2inside) return 2;
  if (!p1inside && !p2inside) return -1;
 
  Eigen::Vector2d dp = p2 - p1;
  double den = a * dp.x() + b * dp.y();
  if (den == 0) return -1;
  double num = c + a * p1.x() + b * p1.y();
  double t = -num / den;
  if (p1inside) {
    p2 = p1 + dp * t;
    return 1;
  }
  p1 = p1 + dp * t;
  return 0;
}
 
int clipSegmentFov(Eigen::Vector2d& p1, Eigen::Vector2d& p2, double min,
                   double max) {
  bool clip1 = false, clip2 = false;
  // normal to the first line
  double amin = sin(min), bmin = -cos(min);
  int minClip = clipSegmentLine(p1, p2, amin, bmin, 0);
  switch (minClip) {
    case -1:
      return -1;
    case 0:
      clip1 = true;
      break;
    case 1:
      clip2 = true;
      break;
    default:;
  }
  // normal to the second line
  double amax = -sin(max), bmax = cos(max);
  int maxClip = clipSegmentLine(p1, p2, amax, bmax, 0);
  switch (maxClip) {
    case -1:
      return -1;
    case 0:
      clip1 = true;
      break;
    case 1:
      clip2 = true;
      break;
    default:;
  }
  if (clip1)
    if (clip2)
      return 3;
    else
      return 0;
  else if (clip2)
    return 1;
  return 2;
}
 
Eigen::Vector2d computeLineParameters(const Eigen::Vector2d& p1,
                                      const Eigen::Vector2d& p2) {
  Eigen::Vector2d lp;
  Eigen::Vector2d dp = p2 - p1;
  lp[0] = atan2(-dp.x(), dp.y());
  Eigen::Vector2d n(cos(lp[0]), sin(lp[0]));
  lp[1] = n.dot(p1 + p2) * .5;
  return lp;
}
}  // namespace g2o