void NearestNeighborGraph(const vector<Vector3>& pc,int k,Graph::Graph<int,int>& G)
{
vector<Vector> copy(pc.size());
for(size_t i=0;i<copy.size();i++) {
copy[i].resize(3);
pc[i].get(copy[i]);
}
G.Resize(pc.size());
for(size_t i=0;i<pc.size();i++)
G.nodes[i] = (int)i;
KDTree* tree = KDTree::Create(copy,3,pc.size());
vector<Real> dist(k);
vector<int> inds(k);
for(size_t i=0;i<pc.size();i++) {
tree->KClosestPoints(copy[i],k,&dist[0],&inds[0]);
for(int j=0;j<k;j++) {
if(inds[j] == (int)i) continue;
G.AddEdge((int)i,inds[j],0);
}
}
}
