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Fixed KDTree recursion and splitting technique

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This commit is contained in:
Guilhem Lavaux 2012-05-21 14:04:21 -04:00
parent d4a14d7d85
commit 80951b4b52
3 changed files with 113 additions and 33 deletions
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93
src/kdtree_splitters.hpp
View file

@ -12,56 +12,119 @@ namespace CosmoTool
typedef typename KDDef<N,CType>::KDCoordinates coords;
typedef typename KDDef<N,CType>::CoordType ctype;
void check_splitting(KDCell<N,ValType,CType> **cells, uint32_t Ncells, int axis, uint32_t split_index, ctype midCoord)
{
ctype delta = std::numeric_limits<ctype>::max();
assert(split_index < Ncells);
assert(axis < N);
for (uint32_t i = 0; i < split_index; i++)
{
assert(cells[i]->coord[axis] <= midCoord);
delta = min(midCoord-cells[i]->coord[axis], delta);
}
for (uint32_t i = split_index+1; i < Ncells; i++)
{
assert(cells[i]->coord[axis] > midCoord);
delta = min(cells[i]->coord[axis]-midCoord, delta);
}
assert(delta >= 0);
assert (std::abs(cells[split_index]->coord[axis]-midCoord) <= delta);
}
void operator()(KDCell<N,ValType,CType> **cells, uint32_t Ncells, uint32_t& split_index, int axis, coords minBound, coords maxBound)
{
if (Ncells == 1)
{
split_index = 0;
return;
}
ctype midCoord = 0.5*(maxBound[axis]+minBound[axis]);
uint32_t below = 0, above = Ncells-1;
ctype delta_max = std::abs(cells[0]->coord[axis]-midCoord);
uint32_t idx_max = 0;
ctype delta_min = std::numeric_limits<ctype>::max();
uint32_t idx_min = std::numeric_limits<uint32_t>::max();
while (below < above)
{
ctype delta = cells[below]->coord[axis]-midCoord;
if (delta > 0)
{
if (delta < delta_max)
if (delta < delta_min)
{
delta_max = delta;
idx_max = above;
delta_min = delta;
idx_min = above;
}
std::swap(cells[below], cells[above--]);
}
else
{
if (-delta < delta_max)
if (-delta < delta_min)
{
delta_max = -delta;
idx_max = below;
delta_min = -delta;
idx_min = below;
}
below++;
}
}
if (idx_max != above)
// Last iteration
{
ctype delta = cells[below]->coord[axis]-midCoord;
if (delta > 0)
{
if (delta < delta_min)
{
delta_min = delta;
idx_min = above;
}
}
else
{
if (-delta < delta_min)
{
delta_min = -delta;
idx_min = above;
}
}
}
if (idx_min != above)
{
bool cond1 = cells[idx_max]->coord[axis] > midCoord;
bool cond1 = cells[idx_min]->coord[axis] > midCoord;
bool cond2 = cells[above]->coord[axis] > midCoord;
if ((cond1 && cond2) || (!cond1 && !cond2))
{
split_index = above;
std::swap(cells[above], cells[idx_max]);
std::swap(cells[above], cells[idx_min]);
}
else if (cond2)
{
split_index = above-1;
std::swap(cells[above-1], cells[idx_max]);
if (above >= 1)
{
split_index = above-1;
std::swap(cells[above-1], cells[idx_min]);
}
else
split_index = 0;
assert(split_index >= 0);
}
else
{
split_index = above+1;
std::swap(cells[above+1], cells[idx_max]);
if (above+1 < Ncells)
{
split_index = above+1;
std::swap(cells[above+1], cells[idx_min]);
}
else
split_index = Ncells-1;
assert(split_index < Ncells);
}
}
else split_index = above;
// check_splitting(cells, Ncells, axis, split_index, midCoord);
}
};

14
src/mykdtree.tcc
View file

@ -390,11 +390,11 @@ namespace CosmoTool {
// If not it is in 1.
go = node->children[1];
other = node->children[0];
if (go == 0)
{
go = other;
other = 0;
}
// if (go == 0)
// {
// go = other;
//other = 0;
//}
}
if (go != 0)
@ -407,8 +407,8 @@ namespace CosmoTool {
computeDistance(node->value, info.x);
info.queue.push(node->value, thisR2);
info.traversed++;
if (go == 0)
return;
// if (go == 0)
// return;
// Now we found the best. We check whether the hypersphere
// intersect the hyperplane of the other branch