source: GTP/trunk/Lib/Vis/Preprocessing/src/Pvs.h @ 1745

#ifndef __PVS_H
#define __PVS_H

#include <map>
#include <vector>
#include "common.h"

namespace GtpVisibilityPreprocessor {

class KdNode;
class BspNode;
class Ray;
class Intersectable;
class ViewCell;


/** Information stored with a PVS entry. Consists of the number
        the object was seen from the view cell.
*/
template<typename T, typename S>
class PvsEntry 
{
public:

        PvsEntry() {}

        PvsEntry(T sample, const S &data): mObject(sample), mData(data) {}

        T mObject;
        S mData;

        template<typename T, typename S>
        friend int operator< (const PvsEntry<T, S> &a, const PvsEntry<T, S> &b);
};


template<typename T, typename S>
int operator< (const PvsEntry<T, S> &a, const PvsEntry<T, S> &b)
{
        return a.mObject < b.mObject;
} 


template<typename T, typename S>
struct LtSample
{
    bool operator()(const PvsEntry<T, S> &a, const PvsEntry<T, S> &b) const
    {
                return a.mObject < b.mObject;
        } 
};


/** Information stored with a PVS entry. Consists of the number
        the object was seen from the view cell.
*/
class PvsData {
public:
        PvsData() {}
        PvsData(const float sumPdf):
        mSumPdf(sumPdf) {}
        
        // $$JB in order to return meaningfull values
        // it assumes that the sum pdf has been normalized somehow!!!
        inline float GetVisibility() 
        { 
                return mSumPdf; 
        }

        /// sum of probability density of visible sample rays
        float mSumPdf;
};


class MailablePvsData 
{
public:
        // sum of probability density of visible sample rays
        float mSumPdf;
        int mCounter;

        MailablePvsData() {}
        MailablePvsData(const float sumPdf):
        mSumPdf(sumPdf) {}

        // $$JB in order to return meaningfull values
        // it assumes that the sum pdf has been normalized somehow!!!
        float GetVisibility() 
        { 
                return mSumPdf; 
        }

        ////////////////////////////
        //  Mailing stuff

        // last mail id -> warning not thread safe!
        // both mailId and mailbox should be unique for each thread!!!
        static int sMailId;
        static int sReservedMailboxes;

        static void NewMail(const int reserve = 1) {
                sMailId += sReservedMailboxes;
                sReservedMailboxes = reserve;
        }

        void Mail() { mMailbox = sMailId; }
        bool Mailed() const { return mMailbox == sMailId; }

        void Mail(const int mailbox) { mMailbox = sMailId + mailbox; }
        bool Mailed(const int mailbox) const { return mMailbox == sMailId + mailbox; }

        int IncMail() { return ++ mMailbox - sMailId; }
        
        //////////////////////////////////////////

protected:

        int mMailbox;

};


template<typename T, typename S>
class PvsIterator
{
public:
PvsIterator<T, S>(){}
        PvsIterator<T, S>(const typename vector<PvsEntry<T, S> >::const_iterator &itCurrent,
                                          const typename vector<PvsEntry<T, S> >::const_iterator &itEnd):
        mItCurrent(itCurrent), mItEnd(itEnd)
        {
        }

        bool HasMoreEntries() const 
        {
                return (mItCurrent != mItEnd);
        }

        const PvsEntry<T, S> &Next()
        {
                return *(mItCurrent ++);
        }
        
private:
        typename vector<PvsEntry<T, S> >::const_iterator mItCurrent;
        typename vector<PvsEntry<T, S> >::const_iterator mItEnd;
};


/** Template class representing the Potentially Visible Set (PVS) 
        mainly from a view cell, but also e.g., from objects.
*/
template<typename T, typename S>
class Pvs
{
        template<typename T, typename S>
        friend class PvsIterator;

public:

        Pvs(): mSamples(0), mEntries() {}

        /** creates pvs and initializes it with the given entries. 
                Assumes that entries are sorted-
        */
        Pvs(const vector<PvsEntry<T, S> > &samples);
        virtual ~Pvs() {};

        /** Compresses PVS lossless or lossy.
        */
        int Compress() {return 0;}
        int GetSize() const {return (int)mEntries.size();}
        bool Empty() const {return mEntries.empty();}

        /** Normalize the visibility of entries in order to get 
                comparable results.
        */
        void NormalizeMaximum();

        /** Merges pvs of a into this pvs.
                Warning: very slow!
        */
        void MergeInPlace(const Pvs<T, S> &a);

        /** Difference of pvs to pvs b.
                @returns number of different entries.
        */
        int Diff(const Pvs<T, S> &b);

        /** Finds sample in PVS.
                @returns iterator on the sample.
        */
        typename vector<PvsEntry<T, S> >::iterator Find(T sample);

        bool GetSampleContribution(T sample, const float pdf, float &contribution);

        /** Adds sample to PVS. 
                @contribution contribution of sample (0 or 1)
                @returns true if sample was not already in PVS.
        */
        bool AddSample(T sample, const float pdf, float &contribution);

        /** Adds sample to PVS.
                @returns contribution of sample (0 or 1)
        */
        float AddSample(T sample, const float pdf);
        
        /** Adds sample to PVS. Assumes that the pvs is sorted
                @returns contribution of sample (0 or 1)
        */
        float AddSamples(const vector<PvsEntry<T, S> > &samples);

        /** Adds sample to PVS.
                @returns PvsData
        */
        typename std::vector<PvsEntry<T, S> >::iterator AddSample2(T sample, const float pdf);

        /** Subtracts one pvs from another one.
                WARNING: could contains bugs
                @returns new pvs size
        */
        int SubtractPvs(const Pvs<T, S> &pvs);

        /** Returns PVS data, i.e., how often it was seen from the view cell, 
                and the object itsef.
        */
        void GetData(const int index, T &entry, S &data);

        /** Collects the PVS entries and returns them in the vector.
        */
        void CollectEntries(std::vector<T> &entries);

        /** Removes sample from PVS if reference count is zero.
                @param visibleSamples number of references to be removed
        */
        bool RemoveSample(T sample, const float pdf);

        /** Compute continuous PVS difference 
        */
        void ComputeContinuousPvsDifference(Pvs<T, S> &pvs, 
                                                                                float &pvsReduction,
                                                                                float &pvsEnlargement);

        /** Clears the pvs.
        */
        void Clear();

        static int GetEntrySizeByte(); 
        static float GetEntrySize();

        /** Compute continuous PVS difference 
        */
        float GetPvsHomogenity(Pvs<T, S> &pvs);

        static void Merge(Pvs<T, S> &mergedPvs, const Pvs<T, S> &a, const Pvs<T, S> &b);

        int GetSamples() const
        {
                return mSamples;
        }

        typename PvsIterator<T, S> GetIterator() const;

protected:

        /// vector of PVS entries
        vector<PvsEntry<T, S> > mEntries; 
        
        /// Number of samples used to create the PVS
        int mSamples;
};


template <typename T, typename S>
Pvs<T, S>::Pvs(const vector<PvsEntry<T, S> > &samples)
{
        mEntries.reserve(samples.size());
        mEntries = samples;
}


/**
   Compute continuous PVS difference of 'b' with respect to the base PVS (*this).
   Provides separatelly PVS reduction from PVS enlargement.

*/
template <typename T, typename S>
void
Pvs<T, S>::ComputeContinuousPvsDifference(Pvs<T, S> &b,
                                                                                  float &pvsReduction,
                                                                                  float &pvsEnlargement)
{
        pvsReduction = 0.0f;
        pvsEnlargement = 0.0f;

        // Uses sum of log differences, which corresponds to entropy
        std::vector<PvsEntry<T, S> >::iterator it;

        for (it = b.mEntries.begin(); it != b.mEntries.end(); ++ it) 
        {
                float bSumPdf = (*it).mData.mSumPdf;
                float aSumPdf = 0.0f;

                vector<PvsEntry<T, S> >::iterator oit = Find((*it).mObject);            

                const bool entryFound = (it != mEntries.end()) && ((*it).mObject == (*oit).mObject);

                if (entryFound)
                {
                        aSumPdf = (*it).mData.mSumPdf;

                        // mark this entry as processed to avoid double counting
                        (*it).mData.mSumPdf = -aSumPdf;
                }

#if 0
                const float diff = bSumPdf - aSumPdf;

                if (diff > 0.0f) {
                        pvsEnlargement += diff;
                } else {
                        pvsReduction += -diff;
                }
#else
                if (!entryFound)
                        pvsEnlargement += 1.0f;
#endif
        }

        for (it = mEntries.begin(); it != mEntries.end(); ++ it) 
        {
                float aSumPdf = (*it).mData.mSumPdf;
                float bSumPdf = 0.0f;
                if (aSumPdf < 0.0f) {
                
                        // this entry was already accounted for!
                        // just revert it back
                        (*it).mData.mSumPdf = -aSumPdf;
                } else {
                        vector<PvsEntry<T, S> >::iterator oit = b.Find((*it).mObject);

                        const bool entryFound = (it != mEntries.end()) && ((*it).mObject == (*oit).mObject);
                        
                        if (entryFound) {
                                bSumPdf = (*oit).mData.mSumPdf;
                        }
#if 0
                        const float diff = bSumPdf - aSumPdf;

                        if (diff > 0.0f) {
                                pvsEnlargement += diff;
                        } else {
                                pvsReduction += -diff;
                        }

#else
                        if (!entryFound) 
                                pvsReduction += 1.0f;
#endif
                }
        }
}


template <typename T, typename S>
int Pvs<T, S>::Diff(const Pvs<T, S> &b)
{
        int dif = 0;

        std::vector<PvsEntry<T, S> >::const_iterator it;

        for (it = b.mEntries.begin(); it != b.mEntries.end(); ++ it)
        {
                std::vector<PvsEntry<T, S> >::const_iterator bit = Find((*it).first);           
                if (bit == mEntries.end()) ++ dif;
        }

        return dif;
}


template <typename T, typename S> 
void Pvs<T, S>::MergeInPlace(const Pvs<T, S> &a)
{
    const int samples = mSamples + a.mSamples;

        ObjectPvs interPvs;
        
        Merge(interPvs, *this, a);
        
        mEntries.reserve(interPvs.GetSize());
        mEntries = interPvs.mEntries;

        mSamples = samples;
}


template <typename T, typename S>
void Pvs<T, S>::Merge(Pvs<T, S> &mergedPvs, const Pvs<T, S> &a, const Pvs<T, S> &b)
{
        std::vector<PvsEntry<T, S> >::const_iterator ait = a.mEntries.begin(), ait_end = a.mEntries.end();
        std::vector<PvsEntry<T, S> >::const_iterator bit = b.mEntries.begin(), bit_end = b.mEntries.end();
        
        for (; (ait != ait_end); ++ ait)
        {
                Intersectable *aObj = (*ait).mObject;
                Intersectable *bObj = NULL;
                PvsEntry<T, S> aEntry = (*ait);

                for (; (bit != bit_end) && ((*bit).mObject <= (*ait).mObject); ++ bit)
                {
                        bObj = (*bit).mObject;

                        // object found => add up probabilities
                        if (bObj == aEntry.mObject)
                        {
                                PvsData newData(aEntry.mData.mSumPdf + (*bit).mData.mSumPdf);
                                PvsEntry<T, S> entry(bObj, newData);
                                mergedPvs.mEntries.push_back(entry);
                        }
                        else
                        {
                                mergedPvs.mEntries.push_back(*bit);
                        }
                }

                // only push back if objects different 
                // (equal case is handled by second loop)
                if (aObj != bObj)
                {
                        mergedPvs.mEntries.push_back(*ait);
                }
        }

        // add the rest
        for (; (bit != bit_end); ++ bit)
        {
                mergedPvs.mEntries.push_back(*bit);
        }
}


template <typename T, typename S> void Pvs<T, S>::Clear()
{
        mEntries.clear();
}


template <typename T, typename S> 
typename std::vector<PvsEntry<T, S> >::iterator Pvs<T, S>::Find(T sample)
{
        PvsEntry<T, S> dummy(sample, PvsData());
        vector<PvsEntry<T, S> >::iterator it = lower_bound(mEntries.begin(), mEntries.end(), dummy);
                                
        return it;
}


template <typename T, typename S>
void Pvs<T, S>::GetData(const int index, T &entry, S &data)
{
        std::vector<PvsEntry<T, S> >::iterator i = mEntries.begin();
        for (int k = 0; k != index && i != mEntries.end(); ++ i, ++ k);

        entry = (*i).first;
        data = (*i).second;
}


template <typename T, typename S>
float Pvs<T, S>::AddSample(T sample, const float pdf)
{
        ++ mSamples;
        std::vector<PvsEntry<T, S> >::iterator it = Find(sample);

        if ((it != mEntries.end()) && ((*it).mObject == sample))
        {
                S &data = (*it).mData;
                data.mSumPdf += pdf;
                return data.mSumPdf;
        }
        else 
        {
                PvsEntry<T, S> entry(sample, pdf);
                mEntries.insert(it, entry);
                return pdf;
        }
}


template <typename T, typename S>
typename vector< PvsEntry<T, S> >::iterator Pvs<T, S>::AddSample2(T sample, const float pdf)
{
        ++ mSamples;
        std::vector<PvsEntry<T, S> >::iterator it = Find(sample);

        if ((it != mEntries.end()) && ((*it).mObject == sample))
        {
                S &data = (*it).second;
                data->mSumPdf += pdf;
        }
        else 
        {
                PvsEntry<T, S> entry(sample, pdf);
                mEntries.insert(it, entry);
        }

        return it;
}


template <typename T, typename S> 
bool Pvs<T, S>::AddSample(T sample,
                                                  const float pdf,
                                                  float &contribution)
{
        ++ mSamples;

        std::vector<PvsEntry<T, S> >::iterator it = Find(sample);

        if ((it != mEntries.end()) && ((*it).mObject == sample))
        {
                S &data = (*it).mData;

                data.mSumPdf += pdf;
                contribution = pdf / data.mSumPdf;

                return false;
        }
        else 
        {
                PvsEntry<T, S> entry(sample, pdf);

                mEntries.insert(it, entry);
                contribution = 1.0f;

                return true;
        }
}


template <typename T, typename S>
bool Pvs<T, S>::GetSampleContribution(T sample,
                                                                          const float pdf,
                                                                          float &contribution) 
{
        std::vector<PvsEntry<T, S> >::iterator it = Find(sample);

        if (it != mEntries.end() && ((*it).mObject == sample))  
        {
                S &data = (*it).mData;
                contribution = pdf / (data.mSumPdf + pdf);
                return false;
        }
        else 
        {
                contribution = 1.0f;
                return true;
        }
}


template <typename T, typename S>
bool Pvs<T, S>::RemoveSample(T sample, const float pdf)
{
        -- mSamples;

        std::vector<PvsEntry<T, S> >::iterator it = Find(sample);

        if (it == mEntries.end())
                return false;

        S &data = (*it).mData;

        data.mSumPdf -= pdf;

        if (data.mSumPdf <= 0.0f)
        {
                mEntries.erase(it);
        }

        return true;
}


template <typename T, typename S>
int Pvs<T, S>::SubtractPvs(const Pvs<T, S> &pvs)
{
        const int samples = mSamples - pvs.mSamples;

        std::vector<PvsEntry<T, S> >::
                const_iterator it, it_end = pvs.mEntries.end();

        // output PVS of view cell
        for (it = pvs.mEntries.begin(); it != it_end; ++ it) 
                RemoveSample((*it).mObject, (*it).mData.mSumPdf);

        mSamples = samples;

        return GetSize();
}


template <typename T, typename S>
void Pvs<T, S>::CollectEntries(std::vector<T> &entries)
{
        std::vector<PvsEntry<T, S> >::
                const_iterator it, it_end = mEntries.end();

        // output PVS of view cell
        for (it = mEntries.begin(); it != it_end; ++ it) 
                entries.push_back((*it)->first);
}


template <typename T, typename S>
void Pvs<T, S>::NormalizeMaximum()
{
        std::vector<PvsEntry<T, S> >::
                const_iterator it, it_end = mEntries.end();

        float maxPdfSum = -1.0f;

        // output PVS of view cell
        for (it = mEntries.begin(); it != it_end; ++ it) {
                float sum = (*it)->second.sumPdf;
                if (sum > maxSum)
                        maxSum = sum;
        }

        maxSum = 1.0f / maxSum;

        for (it = mEntries.begin(); it != it_end; ++ it) {
                (*it)->second.sumPdf *= maxSum;
        }

}


template <typename T, typename S>
float Pvs<T, S>::GetEntrySize()
{
        return (float)(sizeof(T) + sizeof(S)) / float(1024 * 1024);
}


template <typename T, typename S>
int Pvs<T, S>::GetEntrySizeByte()
{
        return sizeof(T) + sizeof(S);
}


template <typename T, typename S>
float Pvs<T, S>::GetPvsHomogenity(Pvs<T, S> &pvs) 
{
        float pvsReduction, pvsEnlargement;

        ComputeContinuousPvsDifference(pvs,     pvsReduction, pvsEnlargement);

        return pvsReduction + pvsEnlargement;
}


template <typename T, typename S>
typename PvsIterator<T, S> Pvs<T, S>::GetIterator() const
{
        PvsIterator<T, S> pit(mEntries.begin(), mEntries.end());

        return pit;
}


///////////////////////////////////////

/** Class instantiating the Pvs template for kd tree nodes.
*/
class KdPvs: public Pvs<KdNode *, PvsData>
{
public:
        int Compress();
};


class ObjectPvs: public Pvs<Intersectable *, PvsData>
{
public:
        /** Counts object int the pvs. Different to method "GetSize", not
                only the raw container size is returned,
                but the individual contributions of the entries are summed up.
        */
        float EvalPvsCost() const;
};


////////////
//-- typedefs

typedef PvsEntry<Intersectable *, PvsData> ObjectPvsEntry;
typedef std::vector<ObjectPvsEntry> ObjectPvsEntries;
typedef Pvs<ViewCell *, MailablePvsData> ViewCellPvs;
typedef PvsIterator<Intersectable *, PvsData> ObjectPvsIterator;
}

#endif