void PhotonAccelerator::build(const std::vector<Hitpoint*>& hitpoints)
{
hps = hitpoints;
nodes.reserve(2 * hitpoints.size() - 1);
BVHNode root;
AABB& world_box = root.getAABB();
std::for_each(hps.begin(), hps.end(), [&] (Hitpoint* hp) {
AABB aabb(hp->is.mPosition);
aabb.grow(hp->radius);
world_box.include(aabb);
});
nodes.push_back(root);
build_recursive(0, hps.size(), &nodes[0], 0);
}
void PhotonAccelerator::accumulate(const Intersection& is, Color flux)
{
BVHNode* currentNode = &nodes[0];
AABB& box = currentNode->getAABB();
Point3D point = is.mPosition;
if (!box.inside(point))
return;
std::stack<BVHNode> intersect_stack;
while (true) {
if (currentNode->isLeaf()) {
Vector3D v(point);
for (unsigned int i = currentNode->getIndex(); i < currentNode->getIndex() + currentNode->getNObjs(); ++i) {
Hitpoint& hp = *hps[i];
if ((v - hp.is.mPosition).length() <= hp.radius && hp.is.mNormal * is.mNormal >= 0) {
hp.newPhotonCount += 1;
hp.totalFlux += flux * hp.is.mMaterial->evalBRDF(hp.is, -is.mRay.dir);
}
}
} else {
BVHNode& left_node = nodes[currentNode->getIndex()];
BVHNode& right_node = nodes[currentNode->getIndex() + 1];
AABB& left_box = left_node.getAABB();
AABB& right_box = right_node.getAABB();
bool leftHit, rightHit;
leftHit = left_box.inside(point);
rightHit = right_box.inside(point);
if (leftHit && rightHit) {
currentNode = &left_node;
intersect_stack.push(right_node);
continue;
} else if (leftHit) {
currentNode = &left_node;
continue;
} else if (rightHit) {
currentNode = &right_node;
continue;
}
}
if (intersect_stack.empty())
return;
currentNode = &intersect_stack.top();
intersect_stack.pop();
}
}