christoph/cpp-masssprings
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implement klotski graph closure solving + improve camera controls (panning)

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Christoph Urlacher
2026-02-18 00:53:42 +01:00
parent 039d96eee3
commit 47fcea6bcb
10 changed files with 226 additions and 96 deletions
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35
src/mass_springs.cpp
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@ -1,7 +1,7 @@
#include "mass_springs.hpp"
#include "config.hpp"
#include <cstddef>
#include <format>
#include <raymath.h>
auto Mass::ClearForce() -> void { force = Vector3Zero(); }
@ -44,13 +44,13 @@ auto Mass::VerletUpdate(const float delta_time) -> void {
Vector3 accel_term = Vector3Scale(acceleration, delta_time * delta_time);
// Minimal dampening
displacement = Vector3Scale(displacement, 0.99);
displacement = Vector3Scale(displacement, 1.0 - VERLET_DAMPENING);
position = Vector3Add(Vector3Add(position, displacement), accel_term);
previous_position = temp_position;
}
auto Spring::CalculateSpringForce() -> void {
auto Spring::CalculateSpringForce() const -> void {
Vector3 delta_position;
float current_length;
Vector3 delta_velocity;
@ -74,7 +74,7 @@ auto Spring::CalculateSpringForce() -> void {
}
auto MassSpringSystem::AddMass(float mass, Vector3 position, bool fixed,
std::string state) -> void {
const std::string &state) -> void {
if (!masses.contains(state)) {
masses.insert(std::make_pair(state, Mass(mass, position, fixed)));
}
@ -89,8 +89,18 @@ auto MassSpringSystem::AddSpring(const std::string &massA,
float spring_constant,
float dampening_constant, float rest_length)
-> void {
springs.emplace_back(GetMass(massA), GetMass(massB), spring_constant,
dampening_constant, rest_length);
std::string states;
if (std::hash<std::string>{}(massA) < std::hash<std::string>{}(massB)) {
states = std::format("{}{}", massA, massB);
} else {
states = std::format("{}{}", massB, massA);
}
if (!springs.contains(states)) {
springs.insert(std::make_pair(
states, Spring(GetMass(massA), GetMass(massB), spring_constant,
dampening_constant, rest_length)));
}
}
auto MassSpringSystem::Clear() -> void {
@ -105,7 +115,7 @@ auto MassSpringSystem::ClearForces() -> void {
}
auto MassSpringSystem::CalculateSpringForces() -> void {
for (auto &spring : springs) {
for (auto &[states, spring] : springs) {
spring.CalculateSpringForce();
}
}
@ -116,25 +126,24 @@ auto MassSpringSystem::CalculateRepulsionForces() -> void {
Vector3 dx = Vector3Subtract(mass.position, m.position);
// This can be accelerated with a spatial data structure
if (Vector3Length(dx) >= 3 * DEFAULT_REST_LENGTH) {
if (Vector3Length(dx) >= 3 * REST_LENGTH) {
continue;
}
mass.force =
Vector3Add(mass.force, Vector3Scale(Vector3Normalize(dx),
DEFAULT_REPULSION_FORCE));
mass.force = Vector3Add(
mass.force, Vector3Scale(Vector3Normalize(dx), REPULSION_FORCE));
}
}
}
auto MassSpringSystem::EulerUpdate(const float delta_time) -> void {
auto MassSpringSystem::EulerUpdate(float delta_time) -> void {
for (auto &[state, mass] : masses) {
mass.CalculateVelocity(delta_time);
mass.CalculatePosition(delta_time);
}
}
auto MassSpringSystem::VerletUpdate(const float delta_time) -> void {
auto MassSpringSystem::VerletUpdate(float delta_time) -> void {
for (auto &[state, mass] : masses) {
mass.VerletUpdate(delta_time);
}