diff options
Diffstat (limited to 'include/bvh-node.hpp')
| -rw-r--r-- | include/bvh-node.hpp | 139 |
1 files changed, 100 insertions, 39 deletions
diff --git a/include/bvh-node.hpp b/include/bvh-node.hpp index 4821fc7..72c4bdf 100644 --- a/include/bvh-node.hpp +++ b/include/bvh-node.hpp @@ -90,6 +90,8 @@ public: }
}
+ // TODO: Pack nodes
+
// exporter();
}
@@ -146,36 +148,31 @@ public: return -1;
}
+ std::vector<bvh_node>& nodes;
+ std::vector<temp_node> temp_nodes;
+ std::vector<temp_node> leafs;
+
+ // std::vector<sphere>& spheres;
+ std::vector<triangle>& triangles;
+
+ uint32_t next_node_id = 0;
+
private:
+ static constexpr uint32_t buckets_count = 12;
+
aabb compute_bounds(uint32_t begin, uint32_t end) {
aabb global_box = aabb();
for (uint32_t box_id = begin; box_id < end; box_id++) {
auto leaf = leafs[box_id];
// global_box = aabb::surrounding_box(global_box, spheres[leaf.primitive_id].bounding_box);
- global_box = aabb::surrounding_box(global_box, triangles[leaf.primitive_id].bounding_box);
+ global_box.union_with(triangles[leaf.primitive_id].bounding_box);
}
return global_box;
}
- int32_t find_split_axis(aabb bounding_box) {
- int32_t split_axis = 0;
- float size = 0;
-
- // Find largest axis
- for (size_t id = 0; id < 3; id++) {
- auto current_size = bounding_box.maximum[id] - bounding_box.minimum[id];
- if (current_size > size) {
- size = current_size;
- split_axis = id;
- }
- }
-
- return split_axis;
- }
-
void subdivide(uint32_t parent_id, uint32_t begin, uint32_t end) {
size_t count = end - begin;
if (count == 1) {
@@ -192,22 +189,96 @@ private: temp_nodes[left_id] = leafs[begin];
temp_nodes[right_id] = leafs[begin + 1];
} else {
- int32_t split_axis = find_split_axis(temp_nodes[parent_id].bounding_box);
+ auto parent_bb = temp_nodes[parent_id].bounding_box;
+ int32_t split_axis = parent_bb.maximum_axis();
- std::sort(leafs.begin() + begin, leafs.begin() + end,
- // [&](const bvh_node& a, const bvh_node& b) {
- // return spheres[a.primitive_id].center[split_axis] < spheres[b.primitive_id].center[split_axis];
- // }
- [&](const bvh_node& a, const bvh_node& b) {
- return triangles[a.primitive_id].center()[split_axis] < triangles[b.primitive_id].center()[split_axis];
+ if (count <= 4) {
+ // Subdivide the node by splitting the set in two equal parts
+ std::sort(leafs.begin() + begin, leafs.begin() + end,
+ // [&](const bvh_node& a, const bvh_node& b) {
+ // return spheres[a.primitive_id].center[split_axis] < spheres[b.primitive_id].center[split_axis];
+ // }
+ [&](const bvh_node& a, const bvh_node& b) {
+ return triangles[a.primitive_id].center()[split_axis] < triangles[b.primitive_id].center()[split_axis];
+ }
+ );
+
+ temp_nodes[left_id].bounding_box = compute_bounds(begin, begin + (count / 2));
+ temp_nodes[right_id].bounding_box = compute_bounds(begin + (count / 2), end);
+
+ subdivide(left_id, begin, begin + (count / 2));
+ subdivide(right_id, begin + (count / 2), end);
+ } else {
+ // Subdivide based on SAH
+ struct Bucket {
+ uint32_t count = 0;
+ aabb bb;
+ };
+ Bucket buckets[buckets_count];
+
+ // Split the set in N spatial buckets
+ // Simplify the optimal split axis search to just an axis between each bucket
+ aabb centroid_bounds;
+
+ for (size_t i = begin; i < end; i++) {
+ auto primitive = triangles[leafs[i].primitive_id];
+ centroid_bounds.union_with(primitive.center());
}
- );
- temp_nodes[left_id].bounding_box = compute_bounds(begin, begin + (count / 2));
- temp_nodes[right_id].bounding_box = compute_bounds(begin + (count / 2), end);
+ float split_axis_size = centroid_bounds.maximum[split_axis] - centroid_bounds.minimum[split_axis];
+ for (size_t i = begin; i < end; i++) {
+ auto primitive = triangles[leafs[i].primitive_id];
+ auto normalized_offset = (primitive.center()[split_axis] - centroid_bounds.minimum[split_axis]) / split_axis_size;
+ uint32_t bucket_index = normalized_offset * buckets_count;
+ if (bucket_index == buckets_count) {
+ bucket_index -= 1;
+ }
- subdivide(left_id, begin, begin + (count / 2));
- subdivide(right_id, begin + (count / 2), end);
+ buckets[bucket_index].count++;
+ buckets[bucket_index].bb.union_with(primitive.bounding_box);
+ }
+
+ // Compute each potential split axis cost
+ float buckets_cost[buckets_count - 1] = { 0.f };
+ for (size_t bucket_index = 0; bucket_index < buckets_count - 1; bucket_index++) {
+ aabb right_side_bb, left_side_bb;
+ float right_side_count = 0, left_side_count = 0;
+
+ for (size_t i = 0; i <= bucket_index; i++) {
+ left_side_bb.union_with(buckets[i].bb);
+ left_side_count += buckets[i].count;
+ }
+
+ for (size_t i = bucket_index + 1; i < buckets_count; i++) {
+ right_side_bb.union_with(buckets[i].bb);
+ right_side_count += buckets[i].count;
+ }
+
+ float left = left_side_count * left_side_bb.surface_area();
+ float right = right_side_count * right_side_bb.surface_area();
+ buckets_cost[bucket_index] = 0.125f + (left + right) / parent_bb.surface_area();
+ }
+
+ float min_cost = buckets_cost[0];
+ uint32_t min_cost_bucket = 0;
+ for (size_t bucket_index = 1; bucket_index < buckets_count - 1; bucket_index++) {
+ if (buckets_cost[bucket_index] < min_cost) {
+ min_cost = buckets_cost[bucket_index];
+ min_cost_bucket = bucket_index;
+ }
+ }
+
+ uint32_t middle_primitive_index = buckets[0].count;
+ for (size_t bucket_index = 1; bucket_index <= min_cost_bucket; bucket_index++) {
+ middle_primitive_index += buckets[bucket_index].count;
+ }
+
+ temp_nodes[left_id].bounding_box = compute_bounds(begin, begin + middle_primitive_index);
+ temp_nodes[right_id].bounding_box = compute_bounds(begin + middle_primitive_index, end);
+
+ subdivide(left_id, begin, begin + middle_primitive_index);
+ subdivide(right_id, begin + middle_primitive_index, end);
+ }
}
}
@@ -227,16 +298,6 @@ private: depth_first_order(node.left_id + 1, next_id, new_id);
}
}
-
-public:
- std::vector<bvh_node>& nodes;
- std::vector<temp_node> temp_nodes;
- std::vector<temp_node> leafs;
-
- // std::vector<sphere>& spheres;
- std::vector<triangle>& triangles;
-
- uint32_t next_node_id = 0;
};
#endif // !__BVH_NODE_HPP_
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