christoph/cpp-masssprings
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refactor usage of std::string to refer to states + improve initial mass positioning

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This commit is contained in:
Christoph Urlacher
2026-02-22 00:12:47 +01:00
parent 0d3913e27e
commit cc4f8ce865
7 changed files with 66 additions and 57 deletions
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23
include/klotski.hpp
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@ -190,7 +190,7 @@ public:
#endif
}
State(std::string state)
explicit State(std::string state)
: width(std::stoi(state.substr(1, 1))),
height(std::stoi(state.substr(3, 1))),
restricted(state.substr(0, 1) == "R"), state(state) {
@ -278,15 +278,30 @@ public:
auto GetNextStates() const -> std::vector<State>;
auto Closure() const
-> std::pair<std::unordered_set<std::string>,
std::vector<std::pair<std::string, std::string>>>;
auto Closure() const -> std::pair<std::unordered_set<State>,
std::vector<std::pair<State, State>>>;
};
template <> struct std::hash<State> {
std::size_t operator()(const State &s) const noexcept { return s.Hash(); }
};
template <> struct std::hash<std::pair<State, State>> {
std::size_t operator()(const std::pair<State, State> &s) const noexcept {
auto h1 = std::hash<State>{}(s.first);
auto h2 = std::hash<State>{}(s.second);
return h1 + h2 + (h1 * h2);
}
};
template <> struct std::equal_to<std::pair<State, State>> {
bool operator()(const std::pair<State, State> &a,
const std::pair<State, State> &b) const noexcept {
return (a.first == b.first && a.second == b.second) ||
(a.first == b.second && a.second == b.first);
}
};
using WinCondition = std::function<bool(const State &)>;
#endif

11
include/mass_springs.hpp
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@ -5,7 +5,6 @@
#include "klotski.hpp"
#include <raylib.h>
#include <raymath.h>
#include <string>
#include <unordered_map>
#include <vector>
@ -87,6 +86,7 @@ public:
class MassSpringSystem {
private:
// TODO: Use references
std::vector<Mass *> mass_vec;
std::vector<int> indices;
std::vector<int64_t> cell_ids;
@ -95,8 +95,10 @@ private:
int last_springs_count;
public:
std::unordered_map<std::string, Mass> masses;
std::unordered_map<std::string, Spring> springs;
// This is the main ownership of all the states/masses/springs.
// Everything is stored multiple times but idc.
std::unordered_map<State, Mass> masses;
std::unordered_map<std::pair<State, State>, Spring> springs;
public:
MassSpringSystem() : last_build(REPULSION_GRID_REFRESH) {};
@ -112,8 +114,7 @@ private:
auto BuildGrid() -> void;
public:
auto AddMass(float mass, Vector3 position, bool fixed, const State &state)
-> void;
auto AddMass(float mass, bool fixed, const State &state) -> void;
auto GetMass(const State &state) -> Mass &;

2
include/state.hpp
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@ -25,7 +25,7 @@ public:
: mass_springs(mass_springs), current_preset(0),
current_state(generators[current_preset]()),
previous_state(current_state), edited(false) {
mass_springs.AddMass(MASS, Vector3Zero(), false, current_state);
mass_springs.AddMass(MASS, false, current_state);
}
StateManager(const StateManager &copy) = delete;

15
src/klotski.cpp
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@ -262,11 +262,10 @@ auto State::GetNextStates() const -> std::vector<State> {
return new_states;
}
auto State::Closure() const
-> std::pair<std::unordered_set<std::string>,
std::vector<std::pair<std::string, std::string>>> {
std::unordered_set<std::string> states;
std::vector<std::pair<std::string, std::string>> links;
auto State::Closure() const -> std::pair<std::unordered_set<State>,
std::vector<std::pair<State, State>>> {
std::unordered_set<State> states;
std::vector<std::pair<State, State>> links;
std::unordered_set<State> remaining_states;
remaining_states.insert(*this);
@ -276,10 +275,10 @@ auto State::Closure() const
remaining_states.erase(current);
std::vector<State> new_states = current.GetNextStates();
for (State &s : new_states) {
if (!states.contains(s.state)) {
for (const State &s : new_states) {
if (!states.contains(s)) {
remaining_states.insert(s);
states.insert(s.state);
states.insert(s);
}
links.emplace_back(current.state, s.state);
}

39
src/mass_springs.cpp
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@ -1,10 +1,11 @@
#include "mass_springs.hpp"
#include "config.hpp"
#include <format>
#include <numeric>
#include <raylib.h>
#include <raymath.h>
#include <unordered_map>
#include <utility>
#include <vector>
auto Mass::ClearForce() -> void { force = Vector3Zero(); }
@ -76,33 +77,39 @@ auto Spring::CalculateSpringForce() const -> void {
massB.force = Vector3Add(massB.force, force_b);
}
auto MassSpringSystem::AddMass(float mass, Vector3 position, bool fixed,
const State &state) -> void {
if (!masses.contains(state.state)) {
masses.insert(std::make_pair(state.state, Mass(mass, position, fixed)));
auto MassSpringSystem::AddMass(float mass, bool fixed, const State &state)
-> void {
if (!masses.contains(state)) {
masses.insert(
std::make_pair(state.state, Mass(mass, Vector3Zero(), fixed)));
}
}
auto MassSpringSystem::GetMass(const State &state) -> Mass & {
return masses.at(state.state);
return masses.at(state);
}
auto MassSpringSystem::AddSpring(const State &massA, const State &massB,
float spring_constant,
float dampening_constant, float rest_length)
-> void {
std::string states;
if (std::hash<std::string>{}(massA.state) <
std::hash<std::string>{}(massB.state)) {
states = std::format("{}{}", massA.state, massB.state);
} else {
states = std::format("{}{}", massB.state, massA.state);
}
std::pair<State, State> key = std::make_pair(massA, massB);
if (!springs.contains(key)) {
Mass &a = GetMass(massA);
Mass &b = GetMass(massB);
Vector3 position = a.position;
Vector3 offset = Vector3(static_cast<float>(GetRandomValue(-100, 100)),
static_cast<float>(GetRandomValue(-100, 100)),
static_cast<float>(GetRandomValue(-100, 100)));
offset = Vector3Scale(Vector3Normalize(offset), REST_LENGTH);
if (b.position == Vector3Zero()) {
b.position = Vector3Add(position, offset);
}
if (!springs.contains(states)) {
springs.insert(std::make_pair(
states, Spring(GetMass(massA), GetMass(massB), spring_constant,
dampening_constant, rest_length)));
key, Spring(a, b, spring_constant, dampening_constant, rest_length)));
}
}

6
src/renderer.cpp
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@ -90,7 +90,7 @@ auto OrbitCamera3D::Update(const Mass &current_mass) -> void {
auto Renderer::UpdateCamera(const MassSpringSystem &masssprings,
const State &current) -> void {
const Mass &c = masssprings.masses.at(current.state);
const Mass &c = masssprings.masses.at(current);
camera.Update(c);
}
@ -130,7 +130,7 @@ auto Renderer::DrawMassSprings(const MassSpringSystem &masssprings,
// Draw masses (high performance impact)
for (const auto &[state, mass] : masssprings.masses) {
if (state == current.state) {
if (state == current) {
DrawCube(mass.position, 4 * VERTEX_SIZE, 4 * VERTEX_SIZE, 4 * VERTEX_SIZE,
RED);
} else if (winning_states.contains(state)) {
@ -140,7 +140,7 @@ auto Renderer::DrawMassSprings(const MassSpringSystem &masssprings,
4 * VERTEX_SIZE, BLUE);
}
if (connect_solutions) {
DrawLine3D(mass.position, masssprings.masses.at(current.state).position,
DrawLine3D(mass.position, masssprings.masses.at(current).position,
PURPLE);
}
} else if (masssprings.masses.size() <= DRAW_VERTICES_LIMIT) {

27
src/state.cpp
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@ -1,4 +1,5 @@
#include "state.hpp"
#include "config.hpp"
#include "presets.hpp"
#include <raymath.h>
@ -33,18 +34,10 @@ auto StateManager::NextPreset() -> void {
auto StateManager::FillGraph() -> void {
ClearGraph();
std::pair<std::unordered_set<std::string>,
std::vector<std::pair<std::string, std::string>>>
std::pair<std::unordered_set<State>, std::vector<std::pair<State, State>>>
closure = current_state.Closure();
for (const auto &state : closure.first) {
// TODO: Insert masses in the spring loop and choose the position based on
// the existing mass
Vector3 pos =
Vector3(static_cast<float>(GetRandomValue(-10000, 10000)) / 1000.0,
static_cast<float>(GetRandomValue(-10000, 10000)) / 1000.0,
static_cast<float>(GetRandomValue(-10000, 10000)) / 1000.0);
mass_springs.AddMass(MASS, pos, false, state);
mass_springs.AddMass(MASS, false, state);
}
for (const auto &[from, to] : closure.second) {
mass_springs.AddSpring(from, to, SPRING_CONSTANT, DAMPENING_CONSTANT,
@ -64,15 +57,9 @@ auto StateManager::FillGraph() -> void {
}
auto StateManager::UpdateGraph() -> void {
if (previous_state != current_state.state) {
mass_springs.AddMass(
MASS,
// TODO: Add beside previous_state
Vector3(static_cast<float>(GetRandomValue(-1000, 1000)) / 1000.0,
static_cast<float>(GetRandomValue(-1000, 1000)) / 1000.0,
static_cast<float>(GetRandomValue(-1000, 1000)) / 1000.0),
false, current_state.state);
mass_springs.AddSpring(current_state.state, previous_state, SPRING_CONSTANT,
if (previous_state != current_state) {
mass_springs.AddMass(MASS, false, current_state);
mass_springs.AddSpring(current_state, previous_state, SPRING_CONSTANT,
DAMPENING_CONSTANT, REST_LENGTH);
if (win_conditions[current_preset](current_state)) {
winning_states.insert(current_state);
@ -83,7 +70,7 @@ auto StateManager::UpdateGraph() -> void {
auto StateManager::ClearGraph() -> void {
winning_states.clear();
mass_springs.Clear();
mass_springs.AddMass(MASS, Vector3Zero(), false, current_state);
mass_springs.AddMass(MASS, false, current_state);
// The previous_state is no longer in the graph
previous_state = current_state;