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Codechange: Performance improvement in k-d tree FindNearest()

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Gabda 2019-05-28 13:26:36 +02:00 committed by Niels Martin Hansen
parent 1e5029563c
commit 652fb40652
1 changed files with 5 additions and 3 deletions
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8
src/core/kdtree.hpp
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@ -240,7 +240,7 @@ class Kdtree {
NOT_REACHED(); // a.first == b.first: same element must not be inserted twice
}
/** Search a sub-tree for the element nearest to a given point */
node_distance FindNearestRecursive(CoordT xy[2], size_t node_idx, int level) const
node_distance FindNearestRecursive(CoordT xy[2], size_t node_idx, int level, DistT limit = std::numeric_limits<DistT>::max()) const
{
/* Dimension index of current level */
int dim = level % 2;
@ -261,11 +261,13 @@ class Kdtree {
best = SelectNearestNodeDistance(best, this->FindNearestRecursive(xy, next, level + 1));
}
limit = min(best.second, limit);
/* Check if the distance from current best is worse than distance from target to splitting line,
* if it is we also need to check the other side of the split. */
size_t opposite = (xy[dim] >= c) ? n.left : n.right; // reverse of above
if (opposite != INVALID_NODE && best.second >= abs((int)xy[dim] - (int)c)) {
node_distance other_candidate = this->FindNearestRecursive(xy, opposite, level + 1);
if (opposite != INVALID_NODE && limit >= abs((int)xy[dim] - (int)c)) {
node_distance other_candidate = this->FindNearestRecursive(xy, opposite, level + 1, limit);
best = SelectNearestNodeDistance(best, other_candidate);
}