llprimlinkinfo.h

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#ifndef LL_PRIM_LINK_INFO_H
#define LL_PRIM_LINK_INFO_H

// system includes
#include <iostream>
#include <map>
#include <list>
#include <vector>

// common includes
#include "stdtypes.h"
#include "v3math.h"
#include "llquaternion.h"
#include "llsphere.h"


const F32 MAX_OBJECT_SPAN = 54.f;               // max distance from outside edge of an object to the farthest edge
const F32 OBJECT_SPAN_BONUS = 2.f;              // infinitesimally small prims can always link up to this distance
const S32 MAX_PRIMS_PER_OBJECT = 255;


template < typename DATA_TYPE >
class LLPrimLinkInfo
{
public:
        LLPrimLinkInfo();
        LLPrimLinkInfo( DATA_TYPE data, const LLSphere& sphere );
        ~LLPrimLinkInfo();

        void set( DATA_TYPE data, const LLSphere& sphere );
        void append( DATA_TYPE data, const LLSphere& sphere );
        void getData( std::list< DATA_TYPE >& data_list ) const;
        F32 getDiameter() const;
        LLVector3 getCenter() const;

        // returns 'true' if this info can link with other_info
        bool canLink( const LLPrimLinkInfo< DATA_TYPE >& other_info );

        S32 getPrimCount() const { return mDataMap.size(); }

        void mergeLinkableSet( typename std::list< LLPrimLinkInfo < DATA_TYPE > >& unlinked );

        void transform(const LLVector3& position, const LLQuaternion& rotation);

private:
        // returns number of merges made
        S32 merge(LLPrimLinkInfo< DATA_TYPE >& other_info);

        // returns number of collapses made
        static S32 collapse(typename std::list< LLPrimLinkInfo < DATA_TYPE > >& unlinked );

        void computeBoundingSphere();

        // Internal utility to encapsulate the link rules
        F32 get_max_linkable_span(const LLSphere& first, const LLSphere& second);
        F32 get_span(const LLSphere& first, const LLSphere& second);

private:
        std::map< DATA_TYPE, LLSphere > mDataMap;
        LLSphere mBoundingSphere;
};



template < typename DATA_TYPE >
LLPrimLinkInfo< DATA_TYPE >::LLPrimLinkInfo()
:       mBoundingSphere( LLVector3(0.f, 0.f, 0.f), 0.f )
{
}

template < typename DATA_TYPE >
LLPrimLinkInfo< DATA_TYPE >::LLPrimLinkInfo( DATA_TYPE data, const LLSphere& sphere)
:       mBoundingSphere(sphere)
{
        mDataMap[data] = sphere;
}

template < typename DATA_TYPE >
LLPrimLinkInfo< DATA_TYPE >::~LLPrimLinkInfo()
{
        mDataMap.clear();
}

template < typename DATA_TYPE >
void LLPrimLinkInfo< DATA_TYPE>::set( DATA_TYPE data, const LLSphere& sphere )
{
        if (!mDataMap.empty())
        {
                mDataMap.clear();
        }
        mDataMap[data] = sphere;
        mBoundingSphere = sphere;
}

template < typename DATA_TYPE >
void LLPrimLinkInfo< DATA_TYPE>::append( DATA_TYPE data, const LLSphere& sphere )
{
        mDataMap[data] = sphere;
        if (!mBoundingSphere.contains(sphere))
        {
                computeBoundingSphere();
        }
}

template < typename DATA_TYPE >
void LLPrimLinkInfo< DATA_TYPE >::getData( std::list< DATA_TYPE >& data_list) const
{
        typename std::map< DATA_TYPE, LLSphere >::const_iterator map_itr;
        for (map_itr = mDataMap.begin(); map_itr != mDataMap.end(); ++map_itr)
        {
                data_list.push_back(map_itr->first);
        }
}

template < typename DATA_TYPE >
F32 LLPrimLinkInfo< DATA_TYPE >::getDiameter() const
{ 
        return 2.f * mBoundingSphere.getRadius();
}

template < typename DATA_TYPE >
LLVector3 LLPrimLinkInfo< DATA_TYPE >::getCenter() const
{ 
        return mBoundingSphere.getCenter(); 
}

template < typename DATA_TYPE >
F32 LLPrimLinkInfo< DATA_TYPE >::get_max_linkable_span(const LLSphere& first, const LLSphere& second)
{
        F32 max_span = 3.f * (first.getRadius() + second.getRadius()) + OBJECT_SPAN_BONUS;
        if (max_span > MAX_OBJECT_SPAN)
        {
                max_span = MAX_OBJECT_SPAN;
        }

        return max_span;
}

template < typename DATA_TYPE >
F32 LLPrimLinkInfo< DATA_TYPE >::get_span(const LLSphere& first, const LLSphere& second)
{
        F32 span = (first.getCenter() - second.getCenter()).length()
                                + first.getRadius() + second.getRadius();
        return span;
}

// static
// returns 'true' if this info can link with any part of other_info
template < typename DATA_TYPE >
bool LLPrimLinkInfo< DATA_TYPE >::canLink(const LLPrimLinkInfo& other_info)
{
        F32 max_span = get_max_linkable_span(mBoundingSphere, other_info.mBoundingSphere);

        F32 span = get_span(mBoundingSphere, other_info.mBoundingSphere);
        
        if (span <= max_span)
        {
                // The entire other_info fits inside the max span.
                return TRUE;
        }
        else if (span > max_span + 2.f * other_info.mBoundingSphere.getRadius())
        {
                // there is no way any piece of other_info could link with this one
                return FALSE;
        }

        // there may be a piece of other_info that is linkable
        typename std::map< DATA_TYPE, LLSphere >::const_iterator map_itr;
        for (map_itr = other_info.mDataMap.begin(); map_itr != other_info.mDataMap.end(); ++map_itr)
        {
                const LLSphere& other_sphere = (*map_itr).second;
                max_span = get_max_linkable_span(mBoundingSphere, other_sphere);

                span = get_span(mBoundingSphere, other_sphere);

                if (span <= max_span)
                {
                        // found one piece that is linkable
                        return TRUE;
                }
        }
        return FALSE;
}

// merges elements of 'unlinked' 
// returns number of links made (NOT final prim count, NOR linked prim count)
// and removes any linkable infos from 'unlinked' 
template < typename DATA_TYPE >
void LLPrimLinkInfo< DATA_TYPE >::mergeLinkableSet(std::list< LLPrimLinkInfo< DATA_TYPE > > & unlinked)
{
        bool linked_something = true;
        while (linked_something)
        {
                linked_something = false;

                typename std::list< LLPrimLinkInfo< DATA_TYPE > >::iterator other_itr = unlinked.begin();
                while ( other_itr != unlinked.end()
                           && getPrimCount() < MAX_PRIMS_PER_OBJECT )
                {
                        S32 merge_count = merge(*other_itr);
                        if (merge_count > 0)
                        {
                                linked_something = true;
                        }
                        if (0 == (*other_itr).getPrimCount())
                        {
                                unlinked.erase(other_itr++);
                        }
                        else
                        {
                                ++other_itr;
                        }
                }
                if (!linked_something
                        && unlinked.size() > 1)
                {
                        S32 collapse_count = collapse(unlinked);
                        if (collapse_count > 0)
                        {
                                linked_something = true;
                        }
                }
        }
}

// transforms all of the spheres into a new reference frame
template < typename DATA_TYPE >
void LLPrimLinkInfo< DATA_TYPE >::transform(const LLVector3& position, const LLQuaternion& rotation)
{
        typename std::map< DATA_TYPE, LLSphere >::iterator map_itr;
        for (map_itr = mDataMap.begin(); map_itr != mDataMap.end(); ++map_itr)
        {
                (*map_itr).second.setCenter((*map_itr).second.getCenter() * rotation + position);
        }
        mBoundingSphere.setCenter(mBoundingSphere.getCenter() * rotation + position);
}

// private
// returns number of links made
template < typename DATA_TYPE >
S32 LLPrimLinkInfo< DATA_TYPE >::merge(LLPrimLinkInfo& other_info)
{
        S32 link_count = 0;

//      F32 other_radius = other_info.mBoundingSphere.getRadius();
//      other_info.computeBoundingSphere();
//      if ( other_radius != other_info.mBoundingSphere.getRadius() )
//      {
//              llinfos << "Other bounding sphere changed!!" << llendl;
//      }

//      F32 this_radius = mBoundingSphere.getRadius();
//      computeBoundingSphere();
//      if ( this_radius != mBoundingSphere.getRadius() )
//      {
//              llinfos << "This bounding sphere changed!!" << llendl;
//      }


        F32 max_span = get_max_linkable_span(mBoundingSphere, other_info.mBoundingSphere);

        //  F32 center_dist = (mBoundingSphere.getCenter() - other_info.mBoundingSphere.getCenter()).length();
        //      llinfos << "objects are " << center_dist << "m apart" << llendl;
        F32 span = get_span(mBoundingSphere, other_info.mBoundingSphere);

        F32 span_limit = max_span + (2.f * other_info.mBoundingSphere.getRadius());
        if (span > span_limit)
        {
                // there is no way any piece of other_info could link with this one
                // llinfos << "span too large:  " << span << " vs. " << span_limit << llendl;
                return 0;
        }

        bool completely_linkable = (span <= max_span) ? true : false;

        typename std::map< DATA_TYPE, LLSphere >::iterator map_itr = other_info.mDataMap.begin();
        while (map_itr != other_info.mDataMap.end()
                        && getPrimCount() < MAX_PRIMS_PER_OBJECT )
        {
                DATA_TYPE other_data = (*map_itr).first;
                LLSphere& other_sphere = (*map_itr).second;

                if (!completely_linkable)
                {
                        max_span = get_max_linkable_span(mBoundingSphere, other_sphere);
        
                        F32 span = get_span(mBoundingSphere, other_sphere);

                        if (span > max_span)
                        {
                                ++map_itr;
                                continue;
                        }
                }

                mDataMap[other_data] = other_sphere;
                ++link_count;

                if (!mBoundingSphere.contains(other_sphere) )
                {
                        computeBoundingSphere();
                }

                // remove from the other info
                other_info.mDataMap.erase(map_itr++);
        }

        if (link_count > 0 && other_info.getPrimCount() > 0)
        {
                other_info.computeBoundingSphere();
        }
        return link_count;
}

// links any linkable elements of unlinked
template < typename DATA_TYPE >
S32 LLPrimLinkInfo< DATA_TYPE >::collapse(std::list< LLPrimLinkInfo< DATA_TYPE > > & unlinked)
{ 
        S32 link_count = 0;
        bool linked_something = true;
        while (linked_something)
        {
                linked_something = false;

                typename std::list< LLPrimLinkInfo< DATA_TYPE > >::iterator this_itr = unlinked.begin();
                typename std::list< LLPrimLinkInfo< DATA_TYPE > >::iterator other_itr = this_itr;
                ++other_itr;
                while ( other_itr != unlinked.end() )
                           
                {
                        S32 merge_count = (*this_itr).merge(*other_itr);
                        if (merge_count > 0)
                        {
                                linked_something = true;
                                link_count += merge_count;
                        }
                        if (0 == (*other_itr).getPrimCount())
                        {
                                unlinked.erase(other_itr++);
                        }
                        else
                        {
                                ++other_itr;
                        }
                }
        }
        return link_count;
}


template < typename DATA_TYPE >
void LLPrimLinkInfo< DATA_TYPE >::computeBoundingSphere()
{ 
        std::vector< LLSphere > sphere_list;
        typename std::map< DATA_TYPE, LLSphere >::const_iterator map_itr;
        for (map_itr = mDataMap.begin(); map_itr != mDataMap.end(); ++map_itr)
        {
                sphere_list.push_back(map_itr->second);
        }
        mBoundingSphere = LLSphere::getBoundingSphere(sphere_list);
}


#endif

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