text: /*********************************************************************
  * Software License Agreement (BSD License)
  *
  *  Copyright (c) 2008, Willow Garage, Inc.
  *  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.
  *   * Neither the name of the Willow Garage nor the names of its
  *     contributors may be used to endorse or promote products derived
  *     from this software without specific prior written permission.
  *
  *  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 OWNER 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 LIABILITY, WHETHER IN CONTRACT, STRICT
  *  LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
  *  ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  *  POSSIBILITY OF SUCH DAMAGE.
  *********************************************************************/
  
  /* Author: Ioan Sucan */
  
  #include "ompl/geometric/planners/rrt/RRTConnect.h"
  #include "ompl/base/goals/GoalSampleableRegion.h"
  #include "ompl/tools/config/SelfConfig.h"
  #include "ompl/util/String.h"
  
  ompl::geometric::RRTConnect::RRTConnect(const base::SpaceInformationPtr &si, bool addIntermediateStates)
    : base::Planner(si, addIntermediateStates ? "RRTConnectIntermediate" : "RRTConnect")
  {
      specs_.recognizedGoal = base::GOAL_SAMPLEABLE_REGION;
      specs_.directed = true;
  
      Planner::declareParam<double>("range", this, &RRTConnect::setRange, &RRTConnect::getRange, "0.:1.:10000.");
      Planner::declareParam<bool>("intermediate_states", this, &RRTConnect::setIntermediateStates,
                                  &RRTConnect::getIntermediateStates, "0,1");
  
      connectionPoint_ = std::make_pair<base::State *, base::State *>(nullptr, nullptr);
      distanceBetweenTrees_ = std::numeric_limits<double>::infinity();
      addIntermediateStates_ = addIntermediateStates;
  }
  
  ompl::geometric::RRTConnect::~RRTConnect()
  {
      freeMemory();
  }
  
  void ompl::geometric::RRTConnect::setup()
  {
      Planner::setup();
      tools::SelfConfig sc(si_, getName());
      sc.configurePlannerRange(maxDistance_);
  
      if (!tStart_)
          tStart_.reset(tools::SelfConfig::getDefaultNearestNeighbors<Motion *>(this));
      if (!tGoal_)
          tGoal_.reset(tools::SelfConfig::getDefaultNearestNeighbors<Motion *>(this));
      tStart_->setDistanceFunction([this](const Motion *a, const Motion *b) { return distanceFunction(a, b); });
      tGoal_->setDistanceFunction([this](const Motion *a, const Motion *b) { return distanceFunction(a, b); });
  }
  
  void ompl::geometric::RRTConnect::freeMemory()
  {
      std::vector<Motion *> motions;
  
      if (tStart_)
      {
          tStart_->list(motions);
          for (auto &motion : motions)
          {
              if (motion->state != nullptr)
                  si_->freeState(motion->state);
              delete motion;
          }
      }
  
      if (tGoal_)
      {
          tGoal_->list(motions);
          for (auto &motion : motions)
          {
              if (motion->state != nullptr)
                  si_->freeState(motion->state);
              delete motion;
          }
      }
  }
  
  void ompl::geometric::RRTConnect::clear()
  {
      Planner::clear();
      sampler_.reset();
      freeMemory();
      if (tStart_)
          tStart_->clear();
      if (tGoal_)
          tGoal_->clear();
      connectionPoint_ = std::make_pair<base::State *, base::State *>(nullptr, nullptr);
      distanceBetweenTrees_ = std::numeric_limits<double>::infinity();
  }
  
  ompl::geometric::RRTConnect::GrowState ompl::geometric::RRTConnect::growTree(TreeData &tree, TreeGrowingInfo &tgi,
                                                                               Motion *rmotion)
  {
      /* find closest state in the tree */
      Motion *nmotion = tree->nearest(rmotion);
  
      /* assume we can reach the state we go towards */
      bool reach = true;
  
      /* find state to add */
      base::State *dstate = rmotion->state;
      double d = si_->distance(nmotion->state, rmotion->state);
      if (d > maxDistance_)
      {
          si_->getStateSpace()->interpolate(nmotion->state, rmotion->state, maxDistance_ / d, tgi.xstate);
  
          /* Check if we have moved at all. Due to some stranger state spaces (e.g., the constrained state spaces),
           * interpolate can fail and no progress is made. Without this check, the algorithm gets stuck in a loop as it
           * thinks it is making progress, when none is actually occurring. */
          if (si_->equalStates(nmotion->state, tgi.xstate))
              return TRAPPED;
  
          dstate = tgi.xstate;
          reach = false;
      }
  
      bool validMotion = tgi.start ? si_->checkMotion(nmotion->state, dstate) :
                                     si_->isValid(dstate) && si_->checkMotion(dstate, nmotion->state);
  
      if (!validMotion)
          return TRAPPED;
  
      if (addIntermediateStates_)
      {
          const base::State *astate = tgi.start ? nmotion->state : dstate;
          const base::State *bstate = tgi.start ? dstate : nmotion->state;
  
          std::vector<base::State *> states;
          const unsigned int count = si_->getStateSpace()->validSegmentCount(astate, bstate);
  
          if (si_->getMotionStates(astate, bstate, states, count, true, true))
              si_->freeState(states[0]);
  
          for (std::size_t i = 1; i < states.size(); ++i)
          {
              auto *motion = new Motion;
              motion->state = states[i];
              motion->parent = nmotion;
              motion->root = nmotion->root;
              tree->add(motion);
  
              nmotion = motion;
          }
  
          tgi.xmotion = nmotion;
      }
      else
      {
          auto *motion = new Motion(si_);
          si_->copyState(motion->state, dstate);
          motion->parent = nmotion;
          motion->root = nmotion->root;
          tree->add(motion);
  
          tgi.xmotion = motion;
      }
  
      return reach ? REACHED : ADVANCED;
  }
  
  ompl::base::PlannerStatus ompl::geometric::RRTConnect::solve(const base::PlannerTerminationCondition &ptc)
  {
      checkValidity();
      auto *goal = dynamic_cast<base::GoalSampleableRegion *>(pdef_->getGoal().get());
  
      if (goal == nullptr)
      {
          OMPL_ERROR("%s: Unknown type of goal", getName().c_str());
          return base::PlannerStatus::UNRECOGNIZED_GOAL_TYPE;
      }
  
      while (const base::State *st = pis_.nextStart())
      {
          auto *motion = new Motion(si_);
          si_->copyState(motion->state, st);
          motion->root = motion->state;
          tStart_->add(motion);
      }
  
      if (tStart_->size() == 0)
      {
          OMPL_ERROR("%s: Motion planning start tree could not be initialized!", getName().c_str());
          return base::PlannerStatus::INVALID_START;
      }
  
      if (!goal->couldSample())
      {
          OMPL_ERROR("%s: Insufficient states in sampleable goal region", getName().c_str());
          return base::PlannerStatus::INVALID_GOAL;
      }
  
      if (!sampler_)
          sampler_ = si_->allocStateSampler();
  
      OMPL_INFORM("%s: Starting planning with %d states already in datastructure", getName().c_str(),
                  (int)(tStart_->size() + tGoal_->size()));
  
      TreeGrowingInfo tgi;
      tgi.xstate = si_->allocState();
  
      Motion *approxsol = nullptr;
      double approxdif = std::numeric_limits<double>::infinity();
      auto *rmotion = new Motion(si_);
      base::State *rstate = rmotion->state;
      bool startTree = true;
      bool solved = false;
  
      while (!ptc)
      {
          TreeData &tree = startTree ? tStart_ : tGoal_;
          tgi.start = startTree;
          startTree = !startTree;
          TreeData &otherTree = startTree ? tStart_ : tGoal_;
  
          if (tGoal_->size() == 0 || pis_.getSampledGoalsCount() < tGoal_->size() / 2)
          {
              const base::State *st = tGoal_->size() == 0 ? pis_.nextGoal(ptc) : pis_.nextGoal();
              if (st != nullptr)
              {
                  auto *motion = new Motion(si_);
                  si_->copyState(motion->state, st);
                  motion->root = motion->state;
                  tGoal_->add(motion);
              }
  
              if (tGoal_->size() == 0)
              {
                  OMPL_ERROR("%s: Unable to sample any valid states for goal tree", getName().c_str());
                  break;
              }
          }
  
          /* sample random state */
          sampler_->sampleUniform(rstate);
  
          GrowState gs = growTree(tree, tgi, rmotion);
  
          if (gs != TRAPPED)
          {
              /* remember which motion was just added */
              Motion *addedMotion = tgi.xmotion;
  
              /* attempt to connect trees */
  
              /* if reached, it means we used rstate directly, no need top copy again */
              if (gs != REACHED)
                  si_->copyState(rstate, tgi.xstate);
  
              GrowState gsc = ADVANCED;
              tgi.start = startTree;
              while (gsc == ADVANCED)
                  gsc = growTree(otherTree, tgi, rmotion);
  
              /* update distance between trees */
              const double newDist = tree->getDistanceFunction()(addedMotion, otherTree->nearest(addedMotion));
              if (newDist < distanceBetweenTrees_)
              {
                  distanceBetweenTrees_ = newDist;
                  // OMPL_INFORM("Estimated distance to go: %f", distanceBetweenTrees_);
              }
  
              Motion *startMotion = startTree ? tgi.xmotion : addedMotion;
              Motion *goalMotion = startTree ? addedMotion : tgi.xmotion;
  
              /* if we connected the trees in a valid way (start and goal pair is valid)*/
              if (gsc == REACHED && goal->isStartGoalPairValid(startMotion->root, goalMotion->root))
              {
                  // it must be the case that either the start tree or the goal tree has made some progress
                  // so one of the parents is not nullptr. We go one step 'back' to avoid having a duplicate state
                  // on the solution path
                  if (startMotion->parent != nullptr)
                      startMotion = startMotion->parent;
                  else
                      goalMotion = goalMotion->parent;
  
                  connectionPoint_ = std::make_pair(startMotion->state, goalMotion->state);
  
                  /* construct the solution path */
                  Motion *solution = startMotion;
                  std::vector<Motion *> mpath1;
                  while (solution != nullptr)
                  {
                      mpath1.push_back(solution);
                      solution = solution->parent;
                  }
  
                  solution = goalMotion;
                  std::vector<Motion *> mpath2;
                  while (solution != nullptr)
                  {
                      mpath2.push_back(solution);
                      solution = solution->parent;
                  }
  
                  auto path(std::make_shared<PathGeometric>(si_));
                  path->getStates().reserve(mpath1.size() + mpath2.size());
                  for (int i = mpath1.size() - 1; i >= 0; --i)
                      path->append(mpath1[i]->state);
                  for (auto &i : mpath2)
                      path->append(i->state);
  
                  pdef_->addSolutionPath(path, false, 0.0, getName());
                  solved = true;
                  break;
              }
              else
              {
                  // We didn't reach the goal, but if we were extending the start
                  // tree, then we can mark/improve the approximate path so far.
                  if (!startTree)
                  {
                      // We were working from the startTree.
                      double dist = 0.0;
                      goal->isSatisfied(tgi.xmotion->state, &dist);
                      if (dist < approxdif)
                      {
                          approxdif = dist;
                          approxsol = tgi.xmotion;
                      }
                  }
              }
          }
      }
  
      si_->freeState(tgi.xstate);
      si_->freeState(rstate);
      delete rmotion;
  
      OMPL_INFORM("%s: Created %u states (%u start + %u goal)", getName().c_str(), tStart_->size() + tGoal_->size(),
                  tStart_->size(), tGoal_->size());
  
      if (approxsol && !solved)
      {
          /* construct the solution path */
          std::vector<Motion *> mpath;
          while (approxsol != nullptr)
          {
              mpath.push_back(approxsol);
              approxsol = approxsol->parent;
          }
  
          auto path(std::make_shared<PathGeometric>(si_));
          for (int i = mpath.size() - 1; i >= 0; --i)
              path->append(mpath[i]->state);
          pdef_->addSolutionPath(path, true, approxdif, getName());
          return base::PlannerStatus::APPROXIMATE_SOLUTION;
      }
  
      return solved ? base::PlannerStatus::EXACT_SOLUTION : base::PlannerStatus::TIMEOUT;
  }
  
  void ompl::geometric::RRTConnect::getPlannerData(base::PlannerData &data) const
  {
      Planner::getPlannerData(data);
  
      std::vector<Motion *> motions;
      if (tStart_)
          tStart_->list(motions);
  
      for (auto &motion : motions)
      {
          if (motion->parent == nullptr)
              data.addStartVertex(base::PlannerDataVertex(motion->state, 1));
          else
          {
              data.addEdge(base::PlannerDataVertex(motion->parent->state, 1), base::PlannerDataVertex(motion->state, 1));
          }
      }
  
      motions.clear();
      if (tGoal_)
          tGoal_->list(motions);
  
      for (auto &motion : motions)
      {
          if (motion->parent == nullptr)
              data.addGoalVertex(base::PlannerDataVertex(motion->state, 2));
          else
          {
              // The edges in the goal tree are reversed to be consistent with start tree
              data.addEdge(base::PlannerDataVertex(motion->state, 2), base::PlannerDataVertex(motion->parent->state, 2));
          }
      }
  
      // Add the edge connecting the two trees
      data.addEdge(data.vertexIndex(connectionPoint_.first), data.vertexIndex(connectionPoint_.second));
  
      // Add some info.
      data.properties["approx goal distance REAL"] = ompl::toString(distanceBetweenTrees_);
  }
  