christoph/cpp-masssprings
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implement barnes-hut particle repulsion using octree

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This commit is contained in:
Christoph Urlacher
2026-02-22 23:29:56 +01:00
parent f07f2772c4
commit e43e505110
5 changed files with 302 additions and 8 deletions
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26
include/physics.hpp
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@ -9,6 +9,10 @@
#include "config.hpp"
#include "puzzle.hpp"
#ifdef BARNES_HUT
#include "octree.hpp"
#endif
class Mass {
public:
const float mass;
@ -53,22 +57,32 @@ public:
class MassSpringSystem {
private:
// Uniform grid
std::vector<Mass *> mass_pointers;
#ifdef BARNES_HUT
// Barnes-Hut
Octree octree;
#else
// Uniform grid
std::vector<int> mass_indices;
std::vector<int64_t> cell_ids;
int last_build;
int last_masses_count;
int last_springs_count;
#endif
public:
// This is the main ownership of all the states/masses/springs.
// Everything is stored multiple times but idc.
// TODO: Everything is stored multiple times but idc (currently).
std::unordered_map<State, Mass> masses;
std::unordered_map<std::pair<State, State>, Spring> springs;
public:
MassSpringSystem() : last_build(REPULSION_GRID_REFRESH) {};
MassSpringSystem() {
#ifndef BARNES_HUT
last_build = REPULSION_GRID_REFRESH;
#endif
};
MassSpringSystem(const MassSpringSystem &copy) = delete;
MassSpringSystem &operator=(const MassSpringSystem &copy) = delete;
@ -78,7 +92,11 @@ public:
~MassSpringSystem() {};
private:
#ifdef BARNES_HUT
auto BuildOctree() -> void;
#else
auto BuildUniformGrid() -> void;
#endif
public:
auto AddMass(float mass, bool fixed, const State &state) -> void;
@ -100,7 +118,9 @@ public:
auto VerletUpdate(float delta_time) -> void;
#ifndef BARNES_HUT
auto InvalidateGrid() -> void;
#endif
};
#endif