void KDPhotonsTree::InitTree(const Photons &photons, const size_t index, const Photons::iterator begin, const Photons::iterator end, const size_t depth) {
const size_t dist_it = end - begin;
if(dist_it < 0) {
throw Error("initializing KD tree error");
}
if(dist_it < 1) {
if(index < m_numberOfPhotons && begin != photons.end())m_treeArray[index] = TreeElement(*begin, ST_NON_EXIST);
return;
}
if(dist_it == 1) {
if(index < m_numberOfPhotons)m_treeArray[index] = TreeElement(*begin, ST_LEAF);
return;
}
Point min( GLOBAL_PROPERTIES::INFINITY, GLOBAL_PROPERTIES::INFINITY, GLOBAL_PROPERTIES::INFINITY);
Point max(-GLOBAL_PROPERTIES::INFINITY, -GLOBAL_PROPERTIES::INFINITY, -GLOBAL_PROPERTIES::INFINITY);
for(Photons::iterator it = begin; it != end; it++) {
if(it->position.x() < min.x()) min.x(it->position.x());
if(it->position.y() < min.y()) min.y(it->position.y());
if(it->position.z() < min.z()) min.z(it->position.z());
if(it->position.x() > max.x()) max.x(it->position.x());
if(it->position.y() > max.y()) max.y(it->position.y());
if(it->position.z() > max.z()) max.z(it->position.z());
}
Point distPoint = max - min;
Split_type split =
(distPoint.x() >= distPoint.y() && distPoint.x() >= distPoint.z()) ? ST_X_COORD
: ( (distPoint.y() >= distPoint.z()) ? ST_Y_COORD : ST_Z_COORD );
std::sort(begin, end, split == ST_X_COORD ? x_comp_func : (split == ST_Y_COORD ? y_comp_func : z_comp_func) );
const Photons::iterator middle = begin + ((end - begin)/2);
if(((index << 1) | 1) < m_numberOfPhotons) {
m_treeArray[index] = TreeElement(*middle, split);
if(depth < m_logOfNumberOfThreads) {
// Need to split to two threads (create extra one)
/////////////////////////////////////////////////////////////
// parallelization
/////////////////////////////////////////////////////////////
DWORD tID;
HANDLE handle;
PhotonsTreeBuildThreadArguments *arguments =
new PhotonsTreeBuildThreadArguments(*this, photons, (index << 1), begin, middle, depth+1);
handle = CreateThread(
NULL,
0,
ThreadBuildFunc,
(LPVOID)arguments,
0,
&tID);
/////////////////////////////////////////////////////////////
// Complete second part of tree itself
InitTree(photons, (index << 1) | 1, middle+1, end , depth+1);
// wait for sibling thread to finish his work
WaitForSingleObject(handle, INFINITE);
} else {
InitTree(photons, (index << 1) , begin , middle, depth+1);
InitTree(photons, (index << 1) | 1, middle+1, end , depth+1);
}
} else {
m_treeArray[index] = TreeElement(*middle, ST_LEAF);
}
}
static TreeElement Root(const std::string& root_name)
{
return TreeElement(root_name);
};
