#include "BarnesHutTree.hpp"
#include "Node.hpp"
#include <iostream>
namespace nbody {
using namespace std;
BarnesHutTree::BarnesHutTree() {
}
BarnesHutTree::~BarnesHutTree() {
}
vector<Box> BarnesHutTree::splitBB(Node* node) {
vector<Box> result;
for (unsigned int i = 0; i < 8; i++) {
Box current = node->getBB();
for (unsigned int j = 0; j < 3; j++) {
double middle = current.getMin(j) + (current.getMax(j) - current.getMin(j)) / 2.0;
if (i & (1 << j)) {
current.setMin(j, middle);
} else {
current.setMax(j, middle);
}
}
result.push_back(current);
}
return result;
}
int BarnesHutTree::numberOfChildren() {
return 8;
}
void BarnesHutTree::build(vector<Body> bodies) {
Node* current;
this->clean();
if (bodies.empty()) return;
//insert root node
this->nodes->insertAfter(new Node(this));
current = this->nodes->next;
//assign bodies to root node
current->bodies = bodies;
//setup proper bounding box
current->extendBBforBodies();
current->extendBBtoCube();
current->afterSubtree = current->next;
//iterate over existing boxes and split if it contains too much bodies
while (current != this->nodes) {
if (current->isSplitable()) {
vector<Box> subboxes = this->splitBB(current);
current->leaf = false;
for (vector<Box>::iterator it = subboxes.begin(); it != subboxes.end(); it++) {
Node* child = new Node(this);
child->parent = current;
child->bb = *it;
child->bodies = it->copyBodies(current->bodies);
current->insertAfter(child);
child->nextSibling = current->next;
current->next->prevSibling = child;
if (it != subboxes.begin()) {
child->afterSubtree = child->next;
} else {
child->afterSubtree = current->afterSubtree;
}
}
current->bodies.clear();
}
current = current->next;
}
}
}