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// Copyright Matt Overby 2020.
// Distributed under the MIT License.
#include "admmpd_bvh.h"
#include <numeric> // iota
// Adapted from:
// https://github.com/mattoverby/mclscene/blob/master/include/MCL/BVH.hpp
namespace admmpd {
template <typename T, int DIM>
void AABBTree<T,DIM>::clear()
{
root = std::make_shared<Node>();
}
template <typename T, int DIM>
void AABBTree<T,DIM>::init(const std::vector<AABB> &leaves)
{
root = std::make_shared<Node>();
int np = leaves.size();
if (np==0)
return;
std::vector<int> queue(np);
std::iota(queue.begin(), queue.end(), 0);
create_children(root.get(), queue, leaves);
}
template <typename T, int DIM>
void AABBTree<T,DIM>::update(const std::vector<AABB> &leaves)
{
if (!root || (int)leaves.size()==0)
return;
update_children(root.get(), leaves);
}
template <typename T, int DIM>
bool AABBTree<T,DIM>::traverse(Traverser<T,DIM> &traverser) const
{
if (!root)
return false;
return traverse_children(root.get(), traverser);
}
// If we are traversing with function pointers, we'll just
// wrap our own traverser that calls these functions to
// avoid duplicate traverse_children code.
template <typename T, int DIM>
class TraverserFromFunctionPtrs : public Traverser<T,DIM>
{
using typename Traverser<T,DIM>::AABB;
public:
std::function<void(const AABB&, bool&, const AABB&, bool&, bool&)> t;
std::function<bool(const AABB&, int)> s;
void traverse(
const AABB &left_aabb, bool &go_left,
const AABB &right_aabb, bool &go_right,
bool &go_left_first)
{
t(left_aabb, go_left, right_aabb, go_right, go_left_first);
}
bool stop_traversing(const AABB &aabb, int prim)
{
return s(aabb,prim);
}
};
template <typename T, int DIM>
bool AABBTree<T,DIM>::traverse(
std::function<void(const AABB&, bool&, const AABB&, bool&, bool&)> t,
std::function<bool(const AABB&, int)> s) const
{
if (!root)
return false;
TraverserFromFunctionPtrs<T,DIM> traverser;
traverser.t = t;
traverser.s = s;
return traverse_children(root.get(), traverser);
}
template <typename T, int DIM>
void AABBTree<T,DIM>::create_children(
Node *node,
std::vector<int> &queue,
const std::vector<AABB> &leaves)
{
node->aabb.setEmpty();
int n_queue = queue.size();
if (n_queue == 1)
{
node->prims.emplace_back(queue[0]);
node->aabb = leaves[queue[0]];
return;
}
for (int i=0; i<n_queue; ++i)
{
int q = queue[i];
node->aabb.extend(leaves[q]);
}
struct SortByAxis
{
int axis;
const std::vector<AABB> &aabbs;
SortByAxis(int axis_, const std::vector<AABB> &aabbs_) :
axis(axis_), aabbs(aabbs_) {}
bool operator()(size_t l, size_t r) const
{
return aabbs[l].center()[axis] < aabbs[r].center()[axis];
}
};
// Sort tree and split queue
int sort_axis = 0;
VecType sizes = node->aabb.sizes();
sizes.maxCoeff(&sort_axis);
std::sort(queue.begin(), queue.end(), SortByAxis(sort_axis,leaves));
std::vector<int> left_queue(queue.begin(), queue.begin()+(n_queue/2));
std::vector<int> right_queue(queue.begin()+(n_queue/2), queue.end());
// Recursive top-down constructrion
node->left = new Node();
create_children(node->left, left_queue, leaves);
node->right = new Node();
create_children(node->right, right_queue, leaves);
} // end create children
template <typename T, int DIM>
void AABBTree<T,DIM>::update_children(
Node *node,
const std::vector<AABB> &leaves)
{
node->aabb.setEmpty();
if (node->is_leaf())
{
int np = node->prims.size();
for (int i=0; i<np; ++i)
{
node->aabb.extend(leaves[node->prims[i]]);
}
return;
}
if (node->left != nullptr)
{
update_children(node->left, leaves);
node->aabb.extend(node->left->aabb);
}
if (node->right != nullptr)
{
update_children(node->right, leaves);
node->aabb.extend(node->right->aabb);
}
} // end update children
template <typename T, int DIM>
bool AABBTree<T,DIM>::traverse_children(
const Node *node,
Traverser<T,DIM> &traverser ) const
{
if( node->is_leaf() ){
int np = node->prims.size();
for(int i=0; i<np; ++i)
{
if(traverser.stop_traversing(node->aabb, node->prims[i]))
return true;
}
return false;
}
bool go_left = true;
bool go_right = true;
bool go_left_first = true;
const AABB &left_aabb = (node->left == nullptr ? AABB() : node->left->aabb);
const AABB &right_aabb = (node->right == nullptr ? AABB() : node->right->aabb);
traverser.traverse(
left_aabb, go_left,
right_aabb, go_right,
go_left_first );
if (go_left && go_right)
{
if (go_left_first)
{
if (traverse_children(node->left, traverser)) { return true; }
else { return traverse_children(node->right, traverser); }
}
else
{
if (traverse_children(node->right, traverser)) { return true; }
else { return traverse_children(node->left, traverser); }
}
}
if (go_left && !go_right)
{
return traverse_children(node->left, traverser);
}
if (!go_left && go_right)
{
return traverse_children(node->right, traverser);
}
return false;
} // end traverse children
// Compile types
template class admmpd::AABBTree<double,2>;
template class admmpd::AABBTree<double,3>;
template class admmpd::AABBTree<float,2>;
template class admmpd::AABBTree<float,3>;
template class admmpd::TraverserFromFunctionPtrs<double,2>;
template class admmpd::TraverserFromFunctionPtrs<double,3>;
template class admmpd::TraverserFromFunctionPtrs<float,2>;
template class admmpd::TraverserFromFunctionPtrs<float,3>;
} // namespace admmpd
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