source: trunk/VUT/GtpVisibilityPreprocessor/src/ViewCellBsp.cpp @ 239

#include "Plane3.h"
#include "ViewCellBsp.h"
#include "Mesh.h"
#include "common.h"
#include "ViewCell.h"
#include "Environment.h"
#include "Polygon3.h"

#include <stack>
#include <time.h>
#include <iomanip>

#define INITIAL_TEST_VAL 999999// unreachable high initial value for heuristic evaluation

int BspTree::sTermMaxPolygons = 10;
int BspTree::sTermMaxDepth = 20;
int BspTree::sSplitPlaneStrategy = NEXT_POLYGON; 
int BspTree::sMaxCandidates = 10;

/****************************************************************/
/*                  class BspNode implementation                */
/****************************************************************/

BspNode::BspNode(): mParent(NULL)
{}

BspNode::BspNode(BspInterior *parent): mParent(parent)
{}


bool BspNode::IsRoot() const 
{
        return mParent == NULL;
}

BspInterior *BspNode::GetParent() 
{ 
        return mParent; 
}

void BspNode::SetParent(BspInterior *parent)
{
        mParent = parent;
}

/****************************************************************/
/*              class BspInterior implementation                */
/****************************************************************/


BspInterior::BspInterior(Plane3 plane): mPlane(plane) 
{}

bool BspInterior::IsLeaf() const
{ 
        return false; 
}

BspNode *BspInterior::GetBack() 
{
        return mBack;
}

BspNode *BspInterior::GetFront() 
{
        return mFront;
}

Plane3 *BspInterior::GetPlane()
{
        return &mPlane;
}

void BspInterior::ReplaceChildLink(BspNode *oldChild, BspNode *newChild) 
{
        if (mBack == oldChild)
        {
                mBack = newChild;
        }
    else
        {
                mFront = newChild;
        }
}

void BspInterior::SetupChildLinks(BspNode *b, BspNode *f) 
{
    mBack = b;
    mFront = f;
}

void BspInterior::SplitPolygons(PolygonContainer *polys, 
                                                                PolygonContainer *frontPolys, 
                                                                PolygonContainer *backPolys, 
                                                                int &splits)
{
        while (!polys->empty())
        {
                Polygon3 *poly = polys->back();
                polys->pop_back();

                // test if split is neccessary
                int result = poly->ClassifyPlane(mPlane);

                Polygon3 *front_piece = NULL;
                Polygon3 *back_piece = NULL;

                switch (result)
                {
                        case Polygon3::COINCIDENT:
                                break; // do nothing
                        case Polygon3::FRONT_SIDE:
                                frontPolys->push_back(poly);
                                break;
                        case Polygon3::BACK_SIDE:
                                backPolys->push_back(poly);
                                break;
                        case Polygon3::SPLIT:
                                front_piece = new Polygon3();
                                back_piece = new Polygon3();

                                //-- split polygon
                                poly->Split(&mPlane, front_piece, back_piece, splits);

                                frontPolys->push_back(front_piece);
                                backPolys->push_back(back_piece);
                                
#ifdef _DEBUG
                                Debug << "split " << poly << endl << front << endl << back << endl;
#endif
                                // don't need polygon anymore
                                DEL_PTR(poly);

                                break;
                        default:
                                Debug << "SHOULD NEVER COME HERE\n";
                                break;
                }
        }
}

/****************************************************************/
/*                  class BspLeaf implementation                */
/****************************************************************/

BspLeaf::BspLeaf(ViewCell *viewCell): mViewCell(viewCell) 
{
}

ViewCell *BspLeaf::GetViewCell()
{
        return mViewCell;
}

bool BspLeaf::IsLeaf() const 
{ 
        return true; 
}


/****************************************************************/
/*                  class BspTree implementation                */
/****************************************************************/

BspTree::BspTree(): mTermMaxPolygons(0), mTermMaxDepth(0), mRoot(NULL)
{
        Randomize(); // initialise random generator for heuristics
}
 
const BspTreeStatistics &BspTree::GetStatistics() const 
{
        return mStat;
}

void BspTreeStatistics::Print(ostream &app) const
{
        app << "===== BspTree statistics ===============\n";

        app << setprecision(4);

        app << "#N_RAYS Number of rays )\n"
                << rays <<endl;
        app << "#N_DOMAINS  ( Number of query domains )\n"
                << queryDomains <<endl;

        app << "#N_NODES ( Number of nodes )\n" << nodes << "\n";

        app << "#N_LEAVES ( Number of leaves )\n" << Leaves() << "\n";

        app << "#N_SPLITS ( Number of splits)\n" << splits << "\n";

        app << "#N_RAYREFS ( Number of rayRefs )\n" <<
        rayRefs << "\n";

        app << "#N_RAYRAYREFS  ( Number of rayRefs / ray )\n" <<
        rayRefs/(double)rays << "\n";

        app << "#N_LEAFRAYREFS  ( Number of rayRefs / leaf )\n" <<
        rayRefs/(double)Leaves() << "\n";

        app << "#N_MAXOBJECTREFS  ( Max number of rayRefs / leaf )\n" <<
        maxObjectRefs << "\n";

        app << "#N_NONEMPTYRAYREFS  ( Number of rayRefs in nonEmpty leaves / non empty leaf )\n" <<
        rayRefsNonZeroQuery/(double)(Leaves() - zeroQueryNodes) << "\n";

        app << "#N_LEAFDOMAINREFS  ( Number of query domain Refs / leaf )\n" <<
        objectRefs/(double)Leaves() << "\n";

        app << "#N_PEMPTYLEAVES  ( Percentage of leaves with zero query domains )\n"<<
        zeroQueryNodes*100/(double)Leaves()<<endl;

        app << "#N_PMAXDEPTHLEAVES ( Percentage of leaves at maxdepth )\n"<<
        maxDepthNodes * 100 / (double)Leaves() << endl;

        app << "#N_PMAXDEPTH ( Maximal reached depth )\n" << maxDepth <<endl;

        app << "#N_ADDED_RAYREFS  (Number of dynamically added ray references )\n"<<
        addedRayRefs<<endl;

        app << "#N_REMOVED_RAYREFS  (Number of dynamically removed ray references )\n"<<
        removedRayRefs<<endl;

        //  app << setprecision(4);

        //  app << "#N_CTIME  ( Construction time [s] )\n"
        //      << Time() << " \n";

        app << "===== END OF BspTree statistics ==========\n";
}

BspTree::~BspTree()
{
        std::stack<BspNode *> tStack;

        tStack.push(mRoot);

        while (!tStack.empty())
        {
                BspNode *node = tStack.top();

            tStack.pop();
        
                if (!node->IsLeaf())
                {
                        BspInterior *interior = dynamic_cast<BspInterior *>(node);

                        // push the children on the stack (there are always two children)
                        interior->GetBack()->mParent = NULL;
                        interior->GetFront()->mParent = NULL;

                        tStack.push(interior->GetBack());
                        tStack.push(interior->GetFront());
                }

                DEL_PTR(node);
        }
}


void BspTree::InsertViewCell(ViewCell *viewCell)
{       
        std::stack<BspTraversalData> tStack;
        
        PolygonContainer polys;
        // copy polygon information to guide the split process
        CopyMesh2Polygons(viewCell->GetMesh(), polys);

        BspNode *firstNode = mRoot ? mRoot : new BspLeaf(); // traverse tree or create new one

        tStack.push(BspTraversalData(firstNode, NULL, &polys, 0));

        while (!tStack.empty())
        {
                // filter polygons donw the tree
                BspTraversalData tData = tStack.top();

            tStack.pop();
                                
        if (!tData.mNode->IsLeaf())
                {
                        BspInterior *interior = dynamic_cast<BspInterior *>(tData.mNode);

                        //-- filter view cell polygons down the tree until a leaf is reached
                        PolygonContainer *frontPolys = new PolygonContainer();
                        PolygonContainer *backPolys = new PolygonContainer();

                        int splits = 0;
                        // split viecell polygons with respect to split plane
                        interior->SplitPolygons(tData.mPolygons, frontPolys, backPolys, splits);
                        mStat.splits += splits;

                        // push the children on the stack
                        if (frontPolys->size() > 0) // if polygons on this side of bsp tree
                                tStack.push(BspTraversalData(interior->GetFront(), interior->GetParent(), 
                                                        frontPolys, tData.mDepth + 1));
                        else
                                delete frontPolys;

                        if (backPolys->size() > 0) // if polygons on this side of bsp tree
                                tStack.push(BspTraversalData(interior->GetBack(), interior->GetParent(), 
                                                        backPolys, tData.mDepth + 1));
                        else
                                delete backPolys;
                }
                else // reached leaf => subdivide current viewcell
                {
                        BspNode *root = Subdivide(tStack, tData, NULL);

                        if (!mRoot) // take as root if there is none yet
                                mRoot = root;                           
                }
        }
}

void BspTree::Construct(const ViewCellContainer &viewCells)
{
        // for this type of construction we split until no polygons is left
        mTermMaxPolygons = 0;
        mTermMaxDepth = sTermMaxDepth;

        mStat.nodes = 1;

        // insert all viewcells
        ViewCellContainer::const_iterator it;

        for (it = viewCells.begin(); it != viewCells.end(); ++ it)
        {
                InsertViewCell(*it);
        }
}

void BspTree::CopyMesh2Polygons(Mesh *mesh, PolygonContainer &polys)
{
        FaceContainer::const_iterator fi;
        
        // copy the face data to polygons
        for (fi = mesh->mFaces.begin(); fi != mesh->mFaces.end(); ++ fi)
        {
                Polygon3 *poly = new Polygon3((*fi), mesh);
                polys.push_back(poly);
        }
}

void BspTree::Copy2PolygonSoup(const ObjectContainer &objects, PolygonContainer &polys, int maxPolys)
{
        ObjectContainer::const_iterator it, it_end = objects.end();

        int limit = (maxPolys > 0) ? min((int)objects.size(), maxPolys) : (int)objects.size();

        for (int i = 0; i < limit; ++i)
        {
                Intersectable *object = objects[i];//*it;
                Mesh *mesh = NULL;

                // extract the meshes
                switch (object->Type())
                {
                case Intersectable::MESH_INSTANCE:
                        mesh = dynamic_cast<MeshInstance *>(object)->GetMesh();
                        break;
                case Intersectable::VIEWCELL:
                        mesh = dynamic_cast<ViewCell *>(object)->GetMesh();
                        break;
                default:
                        break;
                }
                
                if (mesh) // copy the mesh data to polygons
                {
                        CopyMesh2Polygons(mesh, polys);
                }
        }

        Debug << "Number of polygons: " << polys.size() << endl;
}

void BspTree::Construct(const ObjectContainer &objects)
{
        Debug << "Constructing tree using object container\n";

        mTermMaxPolygons = sTermMaxPolygons;
        mTermMaxDepth = sTermMaxDepth;

        mStat.nodes = 1;

        std::stack<BspTraversalData> tStack;
        PolygonContainer *polys = new PolygonContainer();
        
        // copy mesh instance polygons into one big polygon soup
        Copy2PolygonSoup(objects, *polys, 100);

        BspTraversalData tData(new BspLeaf(), mRoot->GetParent(), polys, 0);

        tStack.push(tData);

        while (!tStack.empty()) 
        {
                tData = tStack.top();
            tStack.pop();

                // subdivide leaf node
                BspNode *root = Subdivide(tStack, tData);

                if (!mRoot)
                        mRoot = root;
        }
}

BspNode * BspTree::Subdivide(BspTraversalStack &tStack, BspTraversalData &tData, ViewCell *viewCell)
{
        PolygonContainer *backPolys = new PolygonContainer();
        PolygonContainer *frontPolys = new PolygonContainer();

        BspNode *node = SubdivideNode(dynamic_cast<BspLeaf *>(tData.mNode),
                                                                  tData.mParent,
                                                                  tData.mPolygons,
                                                                  tData.mDepth,
                                                                  viewCell,
                                                                  frontPolys,
                                                                  backPolys);

        if (!node->IsLeaf()) // node was subdivided
        {
                BspInterior *interior = dynamic_cast<BspInterior *>(node);

                // push the children on the stack (there are always two children)
                tStack.push(BspTraversalData(interior->GetBack(), interior, backPolys, tData.mDepth + 1));
                tStack.push(BspTraversalData(interior->GetFront(), interior, frontPolys, tData.mDepth + 1));
        }
        else // tree terminates here
        {
                EvaluateLeafStats(tData);
                // don't need to store polygon information => delete polygons
                Polygon3::DeletePolygons(tData.mPolygons);
        }

        return node;
}

Plane3 BspTree::SelectPlane(PolygonContainer *polygons)  const
{
        // simple strategy: just take next polygon
        if (sSplitPlaneStrategy == NEXT_POLYGON)
        {
                return polygons->front()->GetSupportingPlane();
        }
        
        return SelectPlaneHeuristics(polygons, sMaxCandidates);
}

Plane3 BspTree::SelectPlaneHeuristics(PolygonContainer *polygons, int maxTests) const
{
        int bestValue = INITIAL_TEST_VAL;
        Plane3 *bestPlane = NULL;
        
        int limit = min((int)polygons->size(), maxTests);

        for (int i = 0; i < limit; ++i)
        {
                int candidateIdx = Random((int)polygons->size());
                Plane3 candidatePlane = (*polygons)[candidateIdx]->GetSupportingPlane();
                
                // evaluate current candidate
                int candidateValue = EvalSplitPlane(polygons, candidatePlane);
                        
                if (candidateValue < bestValue)
                {
                        bestPlane = &candidatePlane;
                        bestValue = candidateValue;
                        //Debug << "new plane value " << bestValue << endl;
                }
        }
                
        return *bestPlane;
}

int BspTree::EvalSplitPlane(PolygonContainer *polygons, const Plane3 &candidatePlane) const
{
        PolygonContainer::const_iterator it;

        int sum = 0, sum2 = 0;

        for (it = polygons->begin(); it < polygons->end(); ++ it)
        {
                int classification = (*it)->ClassifyPlane(candidatePlane);
                
                if ((sSplitPlaneStrategy == BALANCED_TREE) || (sSplitPlaneStrategy == COMBINED))
                {
                        sum += EvalForBalancedTree(classification);
                }
                
                if ((sSplitPlaneStrategy == LEAST_SPLITS) || (sSplitPlaneStrategy == COMBINED))
                {
                        sum2 += EvalForLeastSplits(classification);
                }
        }

        // return linear combination of both sums
        return abs(sum) + abs(sum2);
}

int BspTree::EvalForBalancedTree(const int classification)
{
        if (classification == Polygon3::FRONT_SIDE)
                return 1;
        else if (classification == Polygon3::BACK_SIDE)
                return -1;

        return 0;
}

int BspTree::EvalForLeastSplits(const int classification)
{
        if (classification == Polygon3::SPLIT)
                return 1;

        return 0;
}

BspNode *BspTree::SubdivideNode(BspLeaf *leaf, 
                                                                BspInterior *parent, 
                                                                PolygonContainer *polys, 
                                                                const int depth, 
                                                                ViewCell *viewCell,
                                                                PolygonContainer *frontPolys, 
                                                                PolygonContainer *backPolys)
{
        // terminate traversal
        if ((polys->size() <= mTermMaxPolygons) || (depth >= mTermMaxDepth))
        {
                return leaf;
        }

         mStat.nodes += 2;

        // add the new nodes to the tree + select subdivision plane
        BspInterior *node = new BspInterior(SelectPlane(polys)); 

#ifdef _DEBUG
        Debug << node << endl;
#endif
        // split polygon according to current plane
        int splits = 0;
        int polySize = polys->size();
        
        node->SplitPolygons(polys, frontPolys, backPolys, splits);
        
        mStat.splits += splits;

        // two new leaves
        BspLeaf *back = new BspLeaf();
        BspLeaf *front = new BspLeaf(viewCell);

        // replace a link from node's parent
        if (parent)
        {
                parent->ReplaceChildLink(leaf, node);
        }

        // and setup child links
        node->SetupChildLinks(back, front);

        DEL_PTR(leaf); // leaf not member of tree anymore

        return node;
}

void BspTree::ParseEnvironment()
{
        environment->GetIntValue("BspTree.Termination.maxDepth", sTermMaxDepth);
        environment->GetIntValue("BspTree.Termination.maxPolygons", sTermMaxPolygons);
        environment->GetIntValue("BspTree.maxCandidates", sMaxCandidates);

        //-- extract strategy to choose the next split plane
        char splitPlaneStrategyStr[60];

        environment->GetStringValue("BspTree.splitPlaneStrategy", splitPlaneStrategyStr);
        
        sSplitPlaneStrategy = BspTree::NEXT_POLYGON;
        
        if (strcmp(splitPlaneStrategyStr, "nextPolygon") == 0)
                sSplitPlaneStrategy = BspTree::NEXT_POLYGON;
        else if (strcmp(splitPlaneStrategyStr, "leastSplits") == 0)
                sSplitPlaneStrategy = BspTree::LEAST_SPLITS;
        else if (strcmp(splitPlaneStrategyStr, "balancedTree") == 0)
                sSplitPlaneStrategy = BspTree::BALANCED_TREE;
        else 
        {
                cerr << "Wrong BSP split plane strategy " << splitPlaneStrategyStr << endl;
                exit(1);
    }
}

void BspTree::EvaluateLeafStats(const BspTraversalData &data)
{
        // the node became a leaf -> evaluate stats for leafs
        BspLeaf *leaf = dynamic_cast<BspLeaf *>(data.mNode);

        if (data.mDepth >= mTermMaxDepth)
        {
                ++ mStat.maxDepthNodes;
        }

        // record maximal depth
        if (data.mDepth > mStat.maxDepth)
                mStat.maxDepth = data.mDepth;

#ifdef _DEBUG
        Debug << "BSP Traversal data. Depth: " << data.mDepth << " (max: " << mTermMaxDepth<< "), #polygons: " << 
          data.mPolygons->size() << " (max: " << mTermMaxPolygons << ")" << endl;
#endif
}
//} // GtpVisibilityPreprocessor