SPARS.cpp

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/* Author: Andrew Dobson */
 
#include "ompl/geometric/planners/prm/SPARS.h"
#include "ompl/geometric/planners/prm/ConnectionStrategy.h"
#include "ompl/base/goals/GoalSampleableRegion.h"
#include "ompl/base/objectives/PathLengthOptimizationObjective.h"
#include "ompl/tools/config/SelfConfig.h"
#include "ompl/tools/config/MagicConstants.h"
#include <thread>
#include <boost/graph/astar_search.hpp>
#include <boost/graph/incremental_components.hpp>
#include <boost/property_map/vector_property_map.hpp>
#include <boost/foreach.hpp>
 
#include "GoalVisitor.hpp"
 
#define foreach BOOST_FOREACH
#define foreach_reverse BOOST_REVERSE_FOREACH
 
ompl::geometric::SPARS::SPARS(const base::SpaceInformationPtr &si)
  : base::Planner(si, "SPARS")
  , geomPath_(si)
  , stateProperty_(boost::get(vertex_state_t(), g_))
  , sparseStateProperty_(boost::get(vertex_state_t(), s_))
  , sparseColorProperty_(boost::get(vertex_color_t(), s_))
  , representativesProperty_(boost::get(vertex_representative_t(), g_))
  , nonInterfaceListsProperty_(boost::get(vertex_list_t(), s_))
  , interfaceListsProperty_(boost::get(vertex_interface_list_t(), s_))
  , weightProperty_(boost::get(boost::edge_weight, g_))
  , sparseDJSets_(boost::get(boost::vertex_rank, s_), boost::get(boost::vertex_predecessor, s_))
{
    specs_.recognizedGoal = base::GOAL_SAMPLEABLE_REGION;
    specs_.approximateSolutions = false;
    specs_.optimizingPaths = true;
    specs_.multithreaded = true;
 
    psimp_ = std::make_shared<PathSimplifier>(si_);
    psimp_->freeStates(false);
 
    Planner::declareParam<double>("stretch_factor", this, &SPARS::setStretchFactor, &SPARS::getStretchFactor, "1.1:0.1:"
                                                                                                              "3.0");
    Planner::declareParam<double>("sparse_delta_fraction", this, &SPARS::setSparseDeltaFraction,
                                  &SPARS::getSparseDeltaFraction, "0.0:0.01:1.0");
    Planner::declareParam<double>("dense_delta_fraction", this, &SPARS::setDenseDeltaFraction,
                                  &SPARS::getDenseDeltaFraction, "0.0:0.0001:0.1");
    Planner::declareParam<unsigned int>("max_failures", this, &SPARS::setMaxFailures, &SPARS::getMaxFailures, "100:10:"
                                                                                                              "3000");
 
    addPlannerProgressProperty("iterations INTEGER", [this] { return getIterationCount(); });
    addPlannerProgressProperty("best cost REAL", [this] { return getBestCost(); });
}
 
ompl::geometric::SPARS::~SPARS()
{
    freeMemory();
}
 
void ompl::geometric::SPARS::setup()
{
    Planner::setup();
    if (!nn_)
        nn_.reset(tools::SelfConfig::getDefaultNearestNeighbors<DenseVertex>(this));
    nn_->setDistanceFunction([this](const DenseVertex a, const DenseVertex b) { return distanceFunction(a, b); });
    if (!snn_)
        snn_.reset(tools::SelfConfig::getDefaultNearestNeighbors<SparseVertex>(this));
    snn_->setDistanceFunction(
        [this](const SparseVertex a, const SparseVertex b) { return sparseDistanceFunction(a, b); });
    if (!connectionStrategy_)
        connectionStrategy_ =
            KStarStrategy<DenseVertex>([this] { return milestoneCount(); }, nn_, si_->getStateDimension());
    double maxExt = si_->getMaximumExtent();
    sparseDelta_ = sparseDeltaFraction_ * maxExt;
    denseDelta_ = denseDeltaFraction_ * maxExt;
 
    // Setup optimization objective
    //
    // If no optimization objective was specified, then default to
    // optimizing path length as computed by the distance() function
    // in the state space.
    if (pdef_)
    {
        if (pdef_->hasOptimizationObjective())
        {
            opt_ = pdef_->getOptimizationObjective();
            if (dynamic_cast<base::PathLengthOptimizationObjective *>(opt_.get()) == nullptr)
                OMPL_WARN("%s: Asymptotic optimality has only been proven with path length optimizaton; convergence "
                          "for other optimizaton objectives is not guaranteed.",
                          getName().c_str());
        }
        else
            opt_ = std::make_shared<base::PathLengthOptimizationObjective>(si_);
    }
    else
    {
        OMPL_INFORM("%s: problem definition is not set, deferring setup completion...", getName().c_str());
        setup_ = false;
    }
}
 
void ompl::geometric::SPARS::setProblemDefinition(const base::ProblemDefinitionPtr &pdef)
{
    Planner::setProblemDefinition(pdef);
    clearQuery();
}
 
void ompl::geometric::SPARS::resetFailures()
{
    consecutiveFailures_ = 0;
}
 
void ompl::geometric::SPARS::clearQuery()
{
    startM_.clear();
    goalM_.clear();
    pis_.restart();
 
    // Clear past solutions if there are any
    if (pdef_)
        pdef_->clearSolutionPaths();
}
 
void ompl::geometric::SPARS::clear()
{
    Planner::clear();
    sampler_.reset();
    freeMemory();
    if (nn_)
        nn_->clear();
    if (snn_)
        snn_->clear();
    clearQuery();
    resetFailures();
    iterations_ = 0;
    bestCost_ = base::Cost(std::numeric_limits<double>::quiet_NaN());
}
 
void ompl::geometric::SPARS::freeMemory()
{
    foreach (DenseVertex v, boost::vertices(g_))
        if (stateProperty_[v] != nullptr)
        {
            si_->freeState(stateProperty_[v]);
            stateProperty_[v] = nullptr;
        }
    foreach (SparseVertex n, boost::vertices(s_))
        if (sparseStateProperty_[n] != nullptr)
        {
            si_->freeState(sparseStateProperty_[n]);
            sparseStateProperty_[n] = nullptr;
        }
    s_.clear();
    g_.clear();
}
 
ompl::geometric::SPARS::DenseVertex ompl::geometric::SPARS::addSample(base::State *workState,
                                                                      const base::PlannerTerminationCondition &ptc)
{
    DenseVertex result = boost::graph_traits<DenseGraph>::null_vertex();
 
    // search for a valid state
    bool found = false;
    while (!found && !ptc)
    {
        unsigned int attempts = 0;
        do
        {
            found = sampler_->sample(workState);
            attempts++;
        } while (attempts < magic::FIND_VALID_STATE_ATTEMPTS_WITHOUT_TERMINATION_CHECK && !found);
    }
 
    if (found)
        result = addMilestone(si_->cloneState(workState));
    return result;
}
 
void ompl::geometric::SPARS::checkForSolution(const base::PlannerTerminationCondition &ptc, base::PathPtr &solution)
{
    auto *goal = static_cast<base::GoalSampleableRegion *>(pdef_->getGoal().get());
    while (!ptc && !addedSolution_)
    {
        // Check for any new goal states
        if (goal->maxSampleCount() > goalM_.size())
        {
            const base::State *st = pis_.nextGoal();
            if (st != nullptr)
            {
                addMilestone(si_->cloneState(st));
                goalM_.push_back(addGuard(si_->cloneState(st), GOAL));
            }
        }
 
        // Check for a solution
        addedSolution_ = haveSolution(startM_, goalM_, solution);
        // Sleep for 1ms
        if (!addedSolution_)
            std::this_thread::sleep_for(std::chrono::milliseconds(1));
    }
}
 
bool ompl::geometric::SPARS::haveSolution(const std::vector<DenseVertex> &starts, const std::vector<DenseVertex> &goals,
                                          base::PathPtr &solution)
{
    base::Goal *g = pdef_->getGoal().get();
    base::Cost sol_cost(opt_->infiniteCost());
    foreach (DenseVertex start, starts)
    {
        foreach (DenseVertex goal, goals)
        {
            // we lock because the connected components algorithm is incremental and may change disjointSets_
            graphMutex_.lock();
            bool same_component = sameComponent(start, goal);
            graphMutex_.unlock();
 
            if (same_component && g->isStartGoalPairValid(sparseStateProperty_[goal], sparseStateProperty_[start]))
            {
                base::PathPtr p = constructSolution(start, goal);
                if (p)
                {
                    base::Cost pathCost = p->cost(opt_);
                    if (opt_->isCostBetterThan(pathCost, bestCost_))
                        bestCost_ = pathCost;
                    // Check if optimization objective is satisfied
                    if (opt_->isSatisfied(pathCost))
                    {
                        solution = p;
                        return true;
                    }
                    if (opt_->isCostBetterThan(pathCost, sol_cost))
                    {
                        solution = p;
                        sol_cost = pathCost;
                    }
                }
            }
        }
    }
 
    return false;
}
 
bool ompl::geometric::SPARS::reachedTerminationCriterion() const
{
    return consecutiveFailures_ >= maxFailures_ || addedSolution_;
}
 
bool ompl::geometric::SPARS::reachedFailureLimit() const
{
    return consecutiveFailures_ >= maxFailures_;
}
 
void ompl::geometric::SPARS::checkQueryStateInitialization()
{
    std::lock_guard<std::mutex> _(graphMutex_);
    if (boost::num_vertices(g_) < 1)
    {
        sparseQueryVertex_ = boost::add_vertex(s_);
        queryVertex_ = boost::add_vertex(g_);
        sparseStateProperty_[sparseQueryVertex_] = nullptr;
        stateProperty_[queryVertex_] = nullptr;
    }
}
 
bool ompl::geometric::SPARS::sameComponent(SparseVertex m1, SparseVertex m2)
{
    return boost::same_component(m1, m2, sparseDJSets_);
}
 
ompl::base::PlannerStatus ompl::geometric::SPARS::solve(const base::PlannerTerminationCondition &ptc)
{
    checkValidity();
    checkQueryStateInitialization();
 
    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;
    }
 
    // Add the valid start states as milestones
    while (const base::State *st = pis_.nextStart())
    {
        addMilestone(si_->cloneState(st));
        startM_.push_back(addGuard(si_->cloneState(st), START));
    }
    if (startM_.empty())
    {
        OMPL_ERROR("%s: There are no valid initial states!", getName().c_str());
        return base::PlannerStatus::INVALID_START;
    }
 
    if (goalM_.empty() && !goal->couldSample())
    {
        OMPL_ERROR("%s: Insufficient states in sampleable goal region", getName().c_str());
        return base::PlannerStatus::INVALID_GOAL;
    }
 
    // Add the valid goal states as milestones
    while (const base::State *st = (goalM_.empty() ? pis_.nextGoal(ptc) : pis_.nextGoal()))
    {
        addMilestone(si_->cloneState(st));
        goalM_.push_back(addGuard(si_->cloneState(st), GOAL));
    }
    if (goalM_.empty())
    {
        OMPL_ERROR("%s: Unable to find any valid goal states", getName().c_str());
        return base::PlannerStatus::INVALID_GOAL;
    }
 
    unsigned int nrStartStatesDense = boost::num_vertices(g_) - 1;   // don't count query vertex
    unsigned int nrStartStatesSparse = boost::num_vertices(s_) - 1;  // don't count query vertex
    OMPL_INFORM("%s: Starting planning with %u dense states, %u sparse states", getName().c_str(), nrStartStatesDense,
                nrStartStatesSparse);
 
    // Reset addedSolution_ member
    addedSolution_ = false;
    resetFailures();
    base::PathPtr sol;
    base::PlannerTerminationCondition ptcOrFail([this, &ptc] { return ptc || reachedFailureLimit(); });
    std::thread slnThread([this, &ptcOrFail, &sol] { checkForSolution(ptcOrFail, sol); });
 
    // Construct planner termination condition which also takes maxFailures_ and addedSolution_ into account
    base::PlannerTerminationCondition ptcOrStop([this, &ptc] { return ptc || reachedTerminationCriterion(); });
    constructRoadmap(ptcOrStop);
 
    // Ensure slnThread is ceased before exiting solve
    slnThread.join();
 
    if (sol)
        pdef_->addSolutionPath(sol, false, -1.0, getName());
 
    OMPL_INFORM("%s: Created %u dense states, %u sparse states", getName().c_str(),
                (unsigned int)(boost::num_vertices(g_) - nrStartStatesDense),
                (unsigned int)(boost::num_vertices(s_) - nrStartStatesSparse));
 
    // Return true if any solution was found.
    if (sol)
    {
        return base::PlannerStatus::EXACT_SOLUTION;
    }
    else
    {
        return reachedFailureLimit() ? base::PlannerStatus::INFEASIBLE : base::PlannerStatus::TIMEOUT;
    }
}
 
void ompl::geometric::SPARS::constructRoadmap(const base::PlannerTerminationCondition &ptc, bool stopOnMaxFail)
{
    if (stopOnMaxFail)
    {
        resetFailures();
        base::PlannerTerminationCondition ptcOrFail([this, &ptc] { return ptc || reachedFailureLimit(); });
        constructRoadmap(ptcOrFail);
    }
    else
        constructRoadmap(ptc);
}
 
void ompl::geometric::SPARS::constructRoadmap(const base::PlannerTerminationCondition &ptc)
{
    checkQueryStateInitialization();
 
    if (!isSetup())
        setup();
    if (!sampler_)
        sampler_ = si_->allocValidStateSampler();
 
    base::State *workState = si_->allocState();
 
    /* The whole neighborhood set which has been most recently computed */
    std::vector<SparseVertex> graphNeighborhood;
 
    /* The visible neighborhood set which has been most recently computed */
    std::vector<SparseVertex> visibleNeighborhood;
 
    /* Storage for the interface neighborhood, populated by getInterfaceNeighborhood() */
    std::vector<DenseVertex> interfaceNeighborhood;
 
    bestCost_ = opt_->infiniteCost();
    while (!ptc)
    {
        iterations_++;
 
        // Generate a single sample, and attempt to connect it to nearest neighbors.
        DenseVertex q = addSample(workState, ptc);
        if (q == boost::graph_traits<DenseGraph>::null_vertex())
            continue;
 
        // Now that we've added to D, try adding to S
        // Start by figuring out who our neighbors are
        getSparseNeighbors(workState, graphNeighborhood);
        filterVisibleNeighbors(workState, graphNeighborhood, visibleNeighborhood);
        // Check for addition for Coverage
        if (!checkAddCoverage(workState, graphNeighborhood))
            // If not for Coverage, then Connectivity
            if (!checkAddConnectivity(workState, graphNeighborhood))
                // Check for the existence of an interface
                if (!checkAddInterface(graphNeighborhood, visibleNeighborhood, q))
                {
                    // Then check to see if it's on an interface
                    getInterfaceNeighborhood(q, interfaceNeighborhood);
                    if (!interfaceNeighborhood.empty())
                    {
                        // Check for addition for spanner prop
                        if (!checkAddPath(q, interfaceNeighborhood))
                            // All of the tests have failed.  Report failure for the sample
                            ++consecutiveFailures_;
                    }
                    else
                        // There's no interface here, so drop it
                        ++consecutiveFailures_;
                }
    }
 
    si_->freeState(workState);
}
 
ompl::geometric::SPARS::DenseVertex ompl::geometric::SPARS::addMilestone(base::State *state)
{
    std::lock_guard<std::mutex> _(graphMutex_);
 
    DenseVertex m = boost::add_vertex(g_);
    stateProperty_[m] = state;
 
    // Which milestones will we attempt to connect to?
    const std::vector<DenseVertex> &neighbors = connectionStrategy_(m);
 
    foreach (DenseVertex n, neighbors)
        if (si_->checkMotion(stateProperty_[m], stateProperty_[n]))
        {
            const double weight = distanceFunction(m, n);
            const DenseGraph::edge_property_type properties(weight);
 
            boost::add_edge(m, n, properties, g_);
        }
 
    nn_->add(m);
 
    // Need to update representative information here...
    calculateRepresentative(m);
 
    std::vector<DenseVertex> interfaceNeighborhood;
    std::set<SparseVertex> interfaceRepresentatives;
 
    getInterfaceNeighborRepresentatives(m, interfaceRepresentatives);
    getInterfaceNeighborhood(m, interfaceNeighborhood);
    addToRepresentatives(m, representativesProperty_[m], interfaceRepresentatives);
    foreach (DenseVertex qp, interfaceNeighborhood)
    {
        removeFromRepresentatives(qp, representativesProperty_[qp]);
        getInterfaceNeighborRepresentatives(qp, interfaceRepresentatives);
        addToRepresentatives(qp, representativesProperty_[qp], interfaceRepresentatives);
    }
 
    return m;
}
 
ompl::geometric::SPARS::SparseVertex ompl::geometric::SPARS::addGuard(base::State *state, GuardType type)
{
    std::lock_guard<std::mutex> _(graphMutex_);
 
    SparseVertex v = boost::add_vertex(s_);
    sparseStateProperty_[v] = state;
    sparseColorProperty_[v] = type;
 
    sparseDJSets_.make_set(v);
 
    snn_->add(v);
    updateRepresentatives(v);
 
    resetFailures();
    return v;
}
 
void ompl::geometric::SPARS::connectSparsePoints(SparseVertex v, SparseVertex vp)
{
    const base::Cost weight(costHeuristic(v, vp));
    const SpannerGraph::edge_property_type properties(weight);
    std::lock_guard<std::mutex> _(graphMutex_);
    boost::add_edge(v, vp, properties, s_);
    sparseDJSets_.union_set(v, vp);
}
 
void ompl::geometric::SPARS::connectDensePoints(DenseVertex v, DenseVertex vp)
{
    const double weight = distanceFunction(v, vp);
    const DenseGraph::edge_property_type properties(weight);
    std::lock_guard<std::mutex> _(graphMutex_);
    boost::add_edge(v, vp, properties, g_);
}
 
bool ompl::geometric::SPARS::checkAddCoverage(const base::State *lastState, const std::vector<SparseVertex> &neigh)
{
    // For each of these neighbors,
    foreach (SparseVertex n, neigh)
        // If path between is free
        if (si_->checkMotion(lastState, sparseStateProperty_[n]))
            // Abort out and return false
            return false;
    // No free paths means we add for coverage
    addGuard(si_->cloneState(lastState), COVERAGE);
    return true;
}
 
bool ompl::geometric::SPARS::checkAddConnectivity(const base::State *lastState, const std::vector<SparseVertex> &neigh)
{
    std::vector<SparseVertex> links;
    // For each neighbor
    for (std::size_t i = 0; i < neigh.size(); ++i)
        // For each other neighbor
        for (std::size_t j = i + 1; j < neigh.size(); ++j)
            // If they are in different components
            if (!sameComponent(neigh[i], neigh[j]))
                // If the paths between are collision free
                if (si_->checkMotion(lastState, sparseStateProperty_[neigh[i]]) &&
                    si_->checkMotion(lastState, sparseStateProperty_[neigh[j]]))
                {
                    links.push_back(neigh[i]);
                    links.push_back(neigh[j]);
                }
 
    if (!links.empty())
    {
        // Add the node
        SparseVertex g = addGuard(si_->cloneState(lastState), CONNECTIVITY);
 
        for (unsigned long link : links)
            // If there's no edge
            if (!boost::edge(g, link, s_).second)
                // And the components haven't been united by previous links
                if (!sameComponent(link, g))
                    connectSparsePoints(g, link);
        return true;
    }
    return false;
}
 
bool ompl::geometric::SPARS::checkAddInterface(const std::vector<SparseVertex> &graphNeighborhood,
                                               const std::vector<SparseVertex> &visibleNeighborhood, DenseVertex q)
{
    // If we have more than 1 neighbor
    if (visibleNeighborhood.size() > 1)
        // If our closest neighbors are also visible
        if (graphNeighborhood[0] == visibleNeighborhood[0] && graphNeighborhood[1] == visibleNeighborhood[1])
            // If our two closest neighbors don't share an edge
            if (!boost::edge(visibleNeighborhood[0], visibleNeighborhood[1], s_).second)
            {
                // If they can be directly connected
                if (si_->checkMotion(sparseStateProperty_[visibleNeighborhood[0]],
                                     sparseStateProperty_[visibleNeighborhood[1]]))
                {
                    // Connect them
                    connectSparsePoints(visibleNeighborhood[0], visibleNeighborhood[1]);
                    // And report that we added to the roadmap
                    resetFailures();
                    // Report success
                    return true;
                }
 
                // Add the new node to the graph, to bridge the interface
                SparseVertex v = addGuard(si_->cloneState(stateProperty_[q]), INTERFACE);
                connectSparsePoints(v, visibleNeighborhood[0]);
                connectSparsePoints(v, visibleNeighborhood[1]);
                // Report success
                return true;
            }
    return false;
}
 
bool ompl::geometric::SPARS::checkAddPath(DenseVertex q, const std::vector<DenseVertex> &neigh)
{
    bool result = false;
 
    // Get q's representative => v
    SparseVertex v = representativesProperty_[q];
 
    // Extract the representatives of neigh => n_rep
    std::set<SparseVertex> n_rep;
    foreach (DenseVertex qp, neigh)
        n_rep.insert(representativesProperty_[qp]);
 
    std::vector<SparseVertex> Xs;
    // for each v' in n_rep
    for (auto it = n_rep.begin(); it != n_rep.end() && !result; ++it)
    {
        SparseVertex vp = *it;
        // Identify appropriate v" candidates => vpps
        std::vector<SparseVertex> VPPs;
        computeVPP(v, vp, VPPs);
 
        foreach (SparseVertex vpp, VPPs)
        {
            double s_max = 0;
            // Find the X nodes to test
            computeX(v, vp, vpp, Xs);
 
            // For each x in xs
            foreach (SparseVertex x, Xs)
            {
                // Compute/Retain MAXimum distance path thorugh S
                double dist = (si_->distance(sparseStateProperty_[x], sparseStateProperty_[v]) +
                               si_->distance(sparseStateProperty_[v], sparseStateProperty_[vp])) /
                              2.0;
                if (dist > s_max)
                    s_max = dist;
            }
 
            DensePath bestDPath;
            DenseVertex best_qpp = boost::graph_traits<DenseGraph>::null_vertex();
            double d_min = std::numeric_limits<double>::infinity();  // Insanely big number
            // For each vpp in vpps
            for (std::size_t j = 0; j < VPPs.size() && !result; ++j)
            {
                SparseVertex vpp = VPPs[j];
                // For each q", which are stored interface nodes on v for i(vpp,v)
                foreach (DenseVertex qpp, interfaceListsProperty_[v][vpp])
                {
                    // check that representatives are consistent
                    assert(representativesProperty_[qpp] == v);
 
                    // If they happen to be the one and same node
                    if (q == qpp)
                    {
                        bestDPath.push_front(stateProperty_[q]);
                        best_qpp = qpp;
                        d_min = 0;
                    }
                    else
                    {
                        // Compute/Retain MINimum distance path on D through q, q"
                        DensePath dPath;
                        computeDensePath(q, qpp, dPath);
                        if (!dPath.empty())
                        {
                            // compute path length
                            double length = 0.0;
                            DensePath::const_iterator jt = dPath.begin();
                            for (auto it = jt + 1; it != dPath.end(); ++it)
                            {
                                length += si_->distance(*jt, *it);
                                jt = it;
                            }
 
                            if (length < d_min)
                            {
                                d_min = length;
                                bestDPath.swap(dPath);
                                best_qpp = qpp;
                            }
                        }
                    }
                }
 
                // If the spanner property is violated for these paths
                if (s_max > stretchFactor_ * d_min)
                {
                    // Need to augment this path with the appropriate neighbor information
                    DenseVertex na = getInterfaceNeighbor(q, vp);
                    DenseVertex nb = getInterfaceNeighbor(best_qpp, vpp);
 
                    bestDPath.push_front(stateProperty_[na]);
                    bestDPath.push_back(stateProperty_[nb]);
 
                    // check consistency of representatives
                    assert(representativesProperty_[na] == vp && representativesProperty_[nb] == vpp);
 
                    // Add the dense path to the spanner
                    addPathToSpanner(bestDPath, vpp, vp);
 
                    // Report success
                    result = true;
                }
            }
        }
    }
    return result;
}
 
double ompl::geometric::SPARS::averageValence() const
{
    double degree = 0.0;
    foreach (DenseVertex v, boost::vertices(s_))
        degree += (double)boost::out_degree(v, s_);
    degree /= (double)boost::num_vertices(s_);
    return degree;
}
 
void ompl::geometric::SPARS::printDebug(std::ostream &out) const
{
    out << "SPARS Debug Output: " << std::endl;
    out << "  Settings: " << std::endl;
    out << "    Max Failures: " << getMaxFailures() << std::endl;
    out << "    Dense Delta Fraction: " << getDenseDeltaFraction() << std::endl;
    out << "    Sparse Delta Fraction: " << getSparseDeltaFraction() << std::endl;
    out << "    Stretch Factor: " << getStretchFactor() << std::endl;
    out << "  Status: " << std::endl;
    out << "    Milestone Count: " << milestoneCount() << std::endl;
    out << "    Guard Count: " << guardCount() << std::endl;
    out << "    Iterations: " << getIterationCount() << std::endl;
    out << "    Average Valence: " << averageValence() << std::endl;
    out << "    Consecutive Failures: " << consecutiveFailures_ << std::endl;
}
 
void ompl::geometric::SPARS::getSparseNeighbors(base::State *inState, std::vector<SparseVertex> &graphNeighborhood)
{
    sparseStateProperty_[sparseQueryVertex_] = inState;
 
    graphNeighborhood.clear();
    snn_->nearestR(sparseQueryVertex_, sparseDelta_, graphNeighborhood);
 
    sparseStateProperty_[sparseQueryVertex_] = nullptr;
}
 
void ompl::geometric::SPARS::filterVisibleNeighbors(base::State *inState,
                                                    const std::vector<SparseVertex> &graphNeighborhood,
                                                    std::vector<SparseVertex> &visibleNeighborhood) const
{
    visibleNeighborhood.clear();
    // Now that we got the neighbors from the NN, we must remove any we can't see
    for (unsigned long i : graphNeighborhood)
        if (si_->checkMotion(inState, sparseStateProperty_[i]))
            visibleNeighborhood.push_back(i);
}
 
ompl::geometric::SPARS::DenseVertex ompl::geometric::SPARS::getInterfaceNeighbor(DenseVertex q, SparseVertex rep)
{
    foreach (DenseVertex vp, boost::adjacent_vertices(q, g_))
        if (representativesProperty_[vp] == rep)
            if (distanceFunction(q, vp) <= denseDelta_)
                return vp;
    throw Exception(name_, "Vertex has no interface neighbor with given representative");
}
 
bool ompl::geometric::SPARS::addPathToSpanner(const DensePath &dense_path, SparseVertex vp, SparseVertex vpp)
{
    // First, check to see that the path has length
    if (dense_path.size() <= 1)
    {
        // The path is 0 length, so simply link the representatives
        connectSparsePoints(vp, vpp);
        resetFailures();
    }
    else
    {
        // We will need to construct a PathGeometric to do this.
        geomPath_.getStates().resize(dense_path.size());
        std::copy(dense_path.begin(), dense_path.end(), geomPath_.getStates().begin());
 
        // Attempt to simplify the path
        psimp_->reduceVertices(geomPath_, geomPath_.getStateCount() * 2);
 
        // we are sure there are at least 2 points left on geomPath_
 
        std::vector<SparseVertex> added_nodes;
        added_nodes.reserve(geomPath_.getStateCount());
        for (std::size_t i = 0; i < geomPath_.getStateCount(); ++i)
        {
            // Add each guard
            SparseVertex ng = addGuard(si_->cloneState(geomPath_.getState(i)), QUALITY);
            added_nodes.push_back(ng);
        }
        // Link them up
        for (std::size_t i = 1; i < added_nodes.size(); ++i)
        {
            connectSparsePoints(added_nodes[i - 1], added_nodes[i]);
        }
        // Don't forget to link them to their representatives
        connectSparsePoints(added_nodes[0], vp);
        connectSparsePoints(added_nodes[added_nodes.size() - 1], vpp);
    }
    geomPath_.getStates().clear();
    return true;
}
 
void ompl::geometric::SPARS::updateRepresentatives(SparseVertex v)
{
    // Get all of the dense samples which may be affected by adding this node
    std::vector<DenseVertex> dense_points;
 
    stateProperty_[queryVertex_] = sparseStateProperty_[v];
 
    nn_->nearestR(queryVertex_, sparseDelta_ + denseDelta_, dense_points);
 
    stateProperty_[queryVertex_] = nullptr;
 
    // For each of those points
    for (unsigned long dense_point : dense_points)
    {
        // Remove that point from the old representative's list(s)
        removeFromRepresentatives(dense_point, representativesProperty_[dense_point]);
        // Update that point's representative
        calculateRepresentative(dense_point);
    }
 
    std::set<SparseVertex> interfaceRepresentatives;
    // For each of the points
    for (unsigned long dense_point : dense_points)
    {
        // Get it's representative
        SparseVertex rep = representativesProperty_[dense_point];
        // Extract the representatives of any interface-sharing neighbors
        getInterfaceNeighborRepresentatives(dense_point, interfaceRepresentatives);
        // For sanity's sake, make sure we clear ourselves out of what this new rep might think of us
        removeFromRepresentatives(dense_point, rep);
        // Add this vertex to it's representative's list for the other representatives
        addToRepresentatives(dense_point, rep, interfaceRepresentatives);
    }
}
 
void ompl::geometric::SPARS::calculateRepresentative(DenseVertex q)
{
    // Get the nearest neighbors within sparseDelta_
    std::vector<SparseVertex> graphNeighborhood;
    getSparseNeighbors(stateProperty_[q], graphNeighborhood);
 
    // For each neighbor
    for (unsigned long i : graphNeighborhood)
        if (si_->checkMotion(stateProperty_[q], sparseStateProperty_[i]))
        {
            // update the representative
            representativesProperty_[q] = i;
            // abort
            break;
        }
}
 
void ompl::geometric::SPARS::addToRepresentatives(DenseVertex q, SparseVertex rep, const std::set<SparseVertex> &oreps)
{
    // If this node supports no interfaces
    if (oreps.empty())
    {
        // Add it to the pool of non-interface nodes
        bool new_insert = nonInterfaceListsProperty_[rep].insert(q).second;
 
        // we expect this was not previously tracked
        if (!new_insert)
            assert(false);
    }
    else
    {
        // otherwise, for every neighbor representative
        foreach (SparseVertex v, oreps)
        {
            assert(rep == representativesProperty_[q]);
            bool new_insert = interfaceListsProperty_[rep][v].insert(q).second;
            if (!new_insert)
                assert(false);
        }
    }
}
 
void ompl::geometric::SPARS::removeFromRepresentatives(DenseVertex q, SparseVertex rep)
{
    // Remove the node from the non-interface points (if there)
    nonInterfaceListsProperty_[rep].erase(q);
 
    // From each of the interfaces
    foreach (SparseVertex vpp, interfaceListsProperty_[rep] | boost::adaptors::map_keys)
    {
        // Remove this node from that list
        interfaceListsProperty_[rep][vpp].erase(q);
    }
}
 
void ompl::geometric::SPARS::computeVPP(SparseVertex v, SparseVertex vp, std::vector<SparseVertex> &VPPs)
{
    foreach (SparseVertex cvpp, boost::adjacent_vertices(v, s_))
        if (cvpp != vp)
            if (!boost::edge(cvpp, vp, s_).second)
                VPPs.push_back(cvpp);
}
 
void ompl::geometric::SPARS::computeX(SparseVertex v, SparseVertex vp, SparseVertex vpp, std::vector<SparseVertex> &Xs)
{
    Xs.clear();
    foreach (SparseVertex cx, boost::adjacent_vertices(vpp, s_))
        if (boost::edge(cx, v, s_).second && !boost::edge(cx, vp, s_).second)
            if (!interfaceListsProperty_[vpp][cx].empty())
                Xs.push_back(cx);
    Xs.push_back(vpp);
}
 
void ompl::geometric::SPARS::getInterfaceNeighborRepresentatives(DenseVertex q,
                                                                 std::set<SparseVertex> &interfaceRepresentatives)
{
    interfaceRepresentatives.clear();
 
    // Get our representative
    SparseVertex rep = representativesProperty_[q];
    // For each neighbor we are connected to
    foreach (DenseVertex n, boost::adjacent_vertices(q, g_))
    {
        // Get his representative
        SparseVertex orep = representativesProperty_[n];
        // If that representative is not our own
        if (orep != rep)
            // If he is within denseDelta_
            if (distanceFunction(q, n) < denseDelta_)
                // Include his rep in the set
                interfaceRepresentatives.insert(orep);
    }
}
 
void ompl::geometric::SPARS::getInterfaceNeighborhood(DenseVertex q, std::vector<DenseVertex> &interfaceNeighborhood)
{
    interfaceNeighborhood.clear();
 
    // Get our representative
    SparseVertex rep = representativesProperty_[q];
 
    // For each neighbor we are connected to
    foreach (DenseVertex n, boost::adjacent_vertices(q, g_))
        // If neighbor representative is not our own
        if (representativesProperty_[n] != rep)
            // If he is within denseDelta_
            if (distanceFunction(q, n) < denseDelta_)
                // Append him to the list
                interfaceNeighborhood.push_back(n);
}
 
ompl::base::PathPtr ompl::geometric::SPARS::constructSolution(const SparseVertex start, const SparseVertex goal) const
{
    std::lock_guard<std::mutex> _(graphMutex_);
 
    boost::vector_property_map<SparseVertex> prev(boost::num_vertices(s_));
 
    try
    {
        // Consider using a persistent distance_map if it's slow
        boost::astar_search(
            s_, start, [this, goal](SparseVertex v) { return costHeuristic(v, goal); },
            boost::predecessor_map(prev)
                .distance_compare([this](base::Cost c1, base::Cost c2) { return opt_->isCostBetterThan(c1, c2); })
                .distance_combine([this](base::Cost c1, base::Cost c2) { return opt_->combineCosts(c1, c2); })
                .distance_inf(opt_->infiniteCost())
                .distance_zero(opt_->identityCost())
                .visitor(AStarGoalVisitor<SparseVertex>(goal)));
    }
    catch (AStarFoundGoal &)
    {
    }
 
    if (prev[goal] == goal)
        throw Exception(name_, "Could not find solution path");
    else
    {
        auto p(std::make_shared<PathGeometric>(si_));
 
        for (SparseVertex pos = goal; prev[pos] != pos; pos = prev[pos])
            p->append(sparseStateProperty_[pos]);
        p->append(sparseStateProperty_[start]);
        p->reverse();
 
        return p;
    }
}
 
void ompl::geometric::SPARS::computeDensePath(const DenseVertex start, const DenseVertex goal, DensePath &path) const
{
    path.clear();
 
    boost::vector_property_map<DenseVertex> prev(boost::num_vertices(g_));
 
    try
    {
        boost::astar_search(g_, start, [this, goal](const DenseVertex a) { return distanceFunction(a, goal); },
                            boost::predecessor_map(prev).visitor(AStarGoalVisitor<DenseVertex>(goal)));
    }
    catch (AStarFoundGoal &)
    {
    }
 
    if (prev[goal] == goal)
        OMPL_WARN("%s: No dense path was found?", getName().c_str());
    else
    {
        for (DenseVertex pos = goal; prev[pos] != pos; pos = prev[pos])
            path.push_front(stateProperty_[pos]);
        path.push_front(stateProperty_[start]);
    }
}
 
void ompl::geometric::SPARS::getPlannerData(base::PlannerData &data) const
{
    Planner::getPlannerData(data);
 
    // Explicitly add start and goal states:
    for (unsigned long i : startM_)
        data.addStartVertex(base::PlannerDataVertex(sparseStateProperty_[i], (int)START));
 
    for (unsigned long i : goalM_)
        data.addGoalVertex(base::PlannerDataVertex(sparseStateProperty_[i], (int)GOAL));
 
    // Adding edges and all other vertices simultaneously
    foreach (const SparseEdge e, boost::edges(s_))
    {
        const SparseVertex v1 = boost::source(e, s_);
        const SparseVertex v2 = boost::target(e, s_);
        data.addEdge(base::PlannerDataVertex(sparseStateProperty_[v1], (int)sparseColorProperty_[v1]),
                     base::PlannerDataVertex(sparseStateProperty_[v2], (int)sparseColorProperty_[v2]));
 
        // Add the reverse edge, since we're constructing an undirected roadmap
        data.addEdge(base::PlannerDataVertex(sparseStateProperty_[v2], (int)sparseColorProperty_[v1]),
                     base::PlannerDataVertex(sparseStateProperty_[v1], (int)sparseColorProperty_[v2]));
    }
 
    // Make sure to add edge-less nodes as well
    foreach (const SparseVertex n, boost::vertices(s_))
        if (boost::out_degree(n, s_) == 0)
            data.addVertex(base::PlannerDataVertex(sparseStateProperty_[n], (int)sparseColorProperty_[n]));
}
 
ompl::base::Cost ompl::geometric::SPARS::costHeuristic(SparseVertex u, SparseVertex v) const
{
    return opt_->motionCostHeuristic(stateProperty_[u], stateProperty_[v]);
}