christoph/cpp-masssprings
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replace physics loop with fixed-step loop

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This commit is contained in:
Christoph Urlacher
2026-02-22 00:27:56 +01:00
parent cc4f8ce865
commit 05172d0d8f
4 changed files with 26 additions and 27 deletions
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39
src/main.cpp
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@ -63,9 +63,13 @@ auto main(int argc, char *argv[]) -> int {
std::chrono::duration<double, std::milli>(0);
std::chrono::duration<double, std::milli> render_time_accumulator =
std::chrono::duration<double, std::milli>(0);
int time_measure_count = 0;
int loop_count = 0;
#endif
float timestep_accumulator = 0.0;
int update_accumulator = 0;
while (!WindowShouldClose()) {
timestep_accumulator += GetFrameTime();
// Input update
state.previous_state = state.current_state;
input.HandleInput();
@ -76,16 +80,17 @@ auto main(int argc, char *argv[]) -> int {
std::chrono::high_resolution_clock::time_point ps =
std::chrono::high_resolution_clock::now();
#endif
for (int i = 0; i < UPDATES_PER_FRAME; ++i) {
while (timestep_accumulator > TIMESTEP) {
mass_springs.ClearForces();
mass_springs.CalculateSpringForces();
mass_springs.CalculateRepulsionForces();
#ifdef VERLET_UPDATE
mass_springs.VerletUpdate(GetFrameTime() / UPDATES_PER_FRAME * SIM_SPEED);
#else
mass_springs.EulerUpdate(GetFrameTime() * SIM_SPEED);
#endif
mass_springs.VerletUpdate(TIMESTEP * SIM_SPEED);
timestep_accumulator -= TIMESTEP;
update_accumulator++;
}
#ifdef PRINT_TIMINGS
std::chrono::high_resolution_clock::time_point pe =
std::chrono::high_resolution_clock::now();
@ -97,6 +102,7 @@ auto main(int argc, char *argv[]) -> int {
std::chrono::high_resolution_clock::time_point rs =
std::chrono::high_resolution_clock::now();
#endif
renderer.UpdateCamera(mass_springs, state.current_state);
renderer.UpdateTextureSizes();
renderer.DrawMassSprings(mass_springs, state.current_state,
@ -107,23 +113,26 @@ auto main(int argc, char *argv[]) -> int {
renderer.DrawMenu(mass_springs, state.current_preset, state.current_state,
state.winning_states);
renderer.DrawTextures();
#ifdef PRINT_TIMINGS
std::chrono::high_resolution_clock::time_point re =
std::chrono::high_resolution_clock::now();
render_time_accumulator += re - rs;
time_measure_count++;
loop_count++;
if (GetTime() - last_print_time > 10.0) {
std::cout << " - Physics time avg: "
<< physics_time_accumulator / time_measure_count << "."
<< std::endl;
std::cout << " - Render time avg: "
<< render_time_accumulator / time_measure_count << "."
<< std::endl;
std::cout << " - Physics time avg: "
<< physics_time_accumulator / loop_count << "." << std::endl;
std::cout << " - Render time avg: "
<< render_time_accumulator / loop_count << "." << std::endl;
std::cout << " - Physics updates avg: "
<< static_cast<float>(update_accumulator) / loop_count
<< "x per frame." << std::endl;
last_print_time = GetTime();
physics_time_accumulator = std::chrono::duration<double, std::milli>(0);
render_time_accumulator = std::chrono::duration<double, std::milli>(0);
time_measure_count = 0;
loop_count = 0;
update_accumulator = 0;
}
#endif
}