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pre-calculate morton codes in threadpool

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This commit is contained in:
Christoph Urlacher
2026-03-06 02:42:30 +01:00
parent c060cfd35d
commit 127e1c81a6
5 changed files with 31 additions and 13 deletions
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5
include/config.hpp
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@ -91,4 +91,9 @@ constexpr Color BLOCK_COLOR = DARKBLUE;
constexpr Color TARGET_BLOCK_COLOR = RED;
constexpr Color WALL_COLOR = BLACK;
// Threadpool
static constexpr int SMALL_TASK_BLOCK_SIZE = 256; // Weirdly larger blocks decrease performance...
static constexpr int LARGE_TASK_BLOCK_SIZE = 256;
#endif

3
include/cpu_spring_system.hpp
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@ -22,9 +22,6 @@ public:
};
public:
static constexpr int SMALL_TASK_BLOCK_SIZE = 256;
static constexpr int LARGE_TASK_BLOCK_SIZE = 256;
octree tree;
// This is the main ownership of all the states/masses/springs.

5
include/octree.hpp
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@ -2,6 +2,7 @@
#define OCTREE_HPP_
#include "util.hpp"
#include "config.hpp"
#include <array>
#include <vector>
@ -98,7 +99,9 @@ public:
[[nodiscard]] auto root() const -> const node&;
// Morton/linear octree implementation
static auto build_octree_morton(octree& t, const std::vector<Vector3>& positions) -> void;
static auto build_octree_morton(octree& t,
const std::vector<Vector3>& positions,
const std::optional<BS::thread_pool<>*>& thread_pool) -> void;
[[nodiscard]] auto calculate_force_morton(int node_idx, const Vector3& pos, int self_id) const -> Vector3;
};

2
src/cpu_layout_engine.cpp
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@ -103,7 +103,7 @@ auto cpu_layout_engine::physics_thread(physics_state& state, const std::optional
last_mass_count = mass_springs.positions.size();
}
#else
octree::build_octree_morton(mass_springs.tree, mass_springs.positions);
octree::build_octree_morton(mass_springs.tree, mass_springs.positions, thread_pool);
#endif
mass_springs.clear_forces();

29
src/octree.cpp
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@ -25,7 +25,9 @@ auto octree::root() const -> const node&
}
// Replaced the 50 line recursive octree insertion with this bitch to gain 5 UPS, FML
auto octree::build_octree_morton(octree& t, const std::vector<Vector3>& positions) -> void
auto octree::build_octree_morton(octree& t,
const std::vector<Vector3>& positions,
const std::optional<BS::thread_pool<>*>& thread_pool) -> void
{
#ifdef TRACY
ZoneScoped;
@ -65,10 +67,21 @@ auto octree::build_octree_morton(octree& t, const std::vector<Vector3>& position
Vector3 pos;
};
// Calculate morton code for each node
std::vector<sort_node> sort_container;
sort_container.reserve(positions.size());
for (uint32_t i = 0; i < positions.size(); ++i) {
sort_container.emplace_back(pos_to_morton(positions[i], root_min, root_max), i, positions[i]);
sort_container.resize(positions.size());
const auto calculate_morton = [&](const uint32_t i)
{
sort_container[i] = {pos_to_morton(positions[i], root_min, root_max), i, positions[i]};
};
if (thread_pool) {
(*thread_pool)->submit_loop(0, positions.size(), calculate_morton, SMALL_TASK_BLOCK_SIZE).wait();
} else {
for (uint32_t i = 0; i < positions.size(); ++i) {
calculate_morton(i);
}
}
// Sort the list by morton codes. Because positions close to each other have similar morten codes,
@ -123,7 +136,7 @@ auto octree::build_octree_morton(octree& t, const std::vector<Vector3>& position
// Leaves at MAX_DEPTH: 1 particle per leaf in morton order (close particles close together)
auto& leafs = tree_levels[MAX_DEPTH];
leafs.reserve(sort_container.size());
const float leaf_size = root_extent / static_cast<float>(MAX_DEPTH);
const float leaf_size = root_extent / static_cast<float>(1u << MAX_DEPTH);
for (const auto& [code, id, pos] : sort_container) {
node leaf;
leaf.leaf = true;
@ -198,12 +211,12 @@ auto octree::build_octree_morton(octree& t, const std::vector<Vector3>& position
const node& child = tree_levels[child_depth][child_local];
// Which octant of this parent does it belong to?
// IMPORTANT: octant comes from the NEXT level after current_depth (i.e. current_depth+1),
// Octant comes from the NEXT level after current_depth,
// but the child might skip levels due to compression.
// We must use the child's "first level under the parent" which is (current_depth+1).
// We must use the child's first level under the parent (current_depth+1).
const int oct = octant_at_level(leaves[k].leaf_code, current_depth + 1, MAX_DEPTH);
// Store *global* child reference: we only have an int slot, so we need a single index space.
// Store global child reference: we only have an int slot, so we need a single index space.
parent.children[oct] = (child_depth << 24) | (child_local & 0x00FFFFFF);
mass_total += child.mass_total;