MobProximityCounter.h

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#pragma once

class cChunk;
class cEntity;


// This class is used to collect, for each Mob, what is the distance of the closest player
// it was first being designed in order to make mobs spawn / despawn / act
// as the behaviour and even life of mobs depends on the distance to closest player
class cMobProximityCounter
{
protected :
    // structs used for later maps (see m_MonsterToDistance and m_DistanceToMonster)
    struct sDistanceAndChunk
    {
        sDistanceAndChunk(double a_Distance, cChunk & a_Chunk) : m_Distance(a_Distance), m_Chunk(&a_Chunk) {}
        double m_Distance;
        cChunk * m_Chunk;
    };
    struct sMonsterAndChunk
    {
        sMonsterAndChunk(cEntity & a_Monster, cChunk & a_Chunk) : m_Monster(a_Monster), m_Chunk(a_Chunk) {}
        cEntity & m_Monster;
        cChunk & m_Chunk;
    };

public :
    typedef std::map<cEntity *, sDistanceAndChunk> tMonsterToDistance;
    typedef std::multimap<double, sMonsterAndChunk> tDistanceToMonster;

protected :
    // this map is filled during collection phase, it will be later transformed into DistanceToMonster
    tMonsterToDistance m_MonsterToDistance;

    // this map is generated after collection phase, in order to access monster by distance to player
    tDistanceToMonster m_DistanceToMonster;

    // this are the collected chunks. Used to determinate the number of elligible chunk for spawning.
    std::set<cChunk*> m_EligibleForSpawnChunks;

protected :
    // transform monsterToDistance map (that was usefull for collecting) into distanceToMonster
    // that will be usefull for picking up.
    void convertMaps();

public :
    // count a mob on a specified chunk with specified distance to an unkown player
    // if the distance is shortest than the one collected, this become the new closest
    // distance and the chunk become the "hosting" chunk (that is the one that will perform the action)
    void CollectMob(cEntity & a_Monster, cChunk & a_Chunk, double a_Distance);

    // return the mobs that are within the range of distance of the closest player they are
    // that means that if a mob is 30 m from a player and 150 m from another one. It will be
    // in the range [0..50] but not in [100..200]
    struct sIterablePair
    {
        tDistanceToMonster::const_iterator m_Begin;
        tDistanceToMonster::const_iterator m_End;
        int m_Count;
    };
    sIterablePair getMobWithinThosesDistances(double a_DistanceMin, double a_DistanceMax);

};