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backported kd tree improvements from monav project: faster with base case 8

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This commit is contained in:
Dennis Luxen 2010-08-12 11:39:06 +00:00
parent b87d6f3c66
commit 171815c9b7
1 changed files with 155 additions and 137 deletions
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26
DataStructures/StaticKDTree.h
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@ -34,6 +34,8 @@ KD Tree coded by Christian Vetter, Monav Project
namespace KDTree {
#define KDTREE_BASESIZE (8)
template< unsigned k, typename T >
class BoundingBox {
public:
@ -83,6 +85,14 @@ public:
struct InputPoint {
T coordinates[k];
Data data;
bool operator==( const InputPoint& right )
{
for ( int i = 0; i < k; i++ ) {
if ( coordinates[i] != right.coordinates[i] )
return false;
}
return true;
}
};
StaticKDTree( std::vector< InputPoint > * points ){
@ -105,13 +115,13 @@ public:
Tree tree = s.top();
s.pop();
if ( tree.left == tree.right )
if ( tree.right - tree.left < KDTREE_BASESIZE )
continue;
Iterator middle = tree.left + ( tree.right - tree.left ) / 2;
#ifdef _GLIBCXX_PARALLEL
__gnu_parallel::nth_element( kdtree + tree.left, kdtree + middle, kdtree + tree.right, Less( tree.dimension ) );
#else
#else
std::nth_element( kdtree + tree.left, kdtree + middle, kdtree + tree.right, Less( tree.dimension ) );
#endif
s.push( Tree( tree.left, middle, ( tree.dimension + 1 ) % k ) );
@ -136,8 +146,17 @@ public:
if ( distance( tree.box, point.coordinates ) >= nearestDistance )
continue;
if ( tree.left == tree.right )
if ( tree.right - tree.left < KDTREE_BASESIZE ) {
for ( unsigned i = tree.left; i < tree.right; i++ ) {
double newDistance = distance( kdtree[i].coordinates, point.coordinates );
if ( newDistance < nearestDistance ) {
nearestDistance = newDistance;
*result = kdtree[i];
found = true;
}
}
continue;
}
Iterator middle = tree.left + ( tree.right - tree.left ) / 2;
@ -166,7 +185,6 @@ public:
s.push( second );
}
}
return found;
}