Handling Large Time Deltas
How can we handle very large time deltas that might occur if the game is paused or minimized?
Handling large time deltas is crucial for maintaining game stability and preventing unexpected behavior when a game is paused, minimized, or experiences a sudden lag spike. Here are some strategies to deal with this issue:
Capping the Time Delta
The simplest approach is to cap the time delta to a maximum value. This prevents the game from trying to catch up all at once if there's a long pause:
#include <SDL.h>
#include <algorithm>
// Maximum of 100ms
const float MAX_DELTA_TIME = 0.1f;
void updateGame(float deltaTime) {
// Game update logic here
}
int main() {
SDL_Init(SDL_INIT_VIDEO);
Uint64 previousTime = SDL_GetTicks64();
while (true) {
Uint64 currentTime = SDL_GetTicks64();
float deltaTime = (currentTime -
previousTime) / 1000.0f;
// Cap the delta time
deltaTime = std::min(deltaTime,
MAX_DELTA_TIME);
updateGame(deltaTime);
previousTime = currentTime;
}
SDL_Quit();
return 0;
}Accumulating Time and Updating in Fixed Steps
Another approach is to accumulate time and update the game in fixed time steps. This method is particularly useful for physics simulations:
#include <SDL.h>
// 60 updates per second
const float FIXED_TIME_STEP = 0.016f;
void updateGame(float deltaTime) {
// Game update logic here
}
int main() {
SDL_Init(SDL_INIT_VIDEO);
Uint64 previousTime = SDL_GetTicks64();
float accumulatedTime = 0.0f;
while (true) {
Uint64 currentTime = SDL_GetTicks64();
float deltaTime = (currentTime -
previousTime) / 1000.0f;
accumulatedTime += deltaTime;
while (accumulatedTime >= FIXED_TIME_STEP) {
updateGame(FIXED_TIME_STEP);
accumulatedTime -= FIXED_TIME_STEP;
}
previousTime = currentTime;
}
SDL_Quit();
return 0;
}This approach ensures that the game logic always updates with a consistent time step, regardless of how much real time has passed.
Pausing Game Logic
When the game is explicitly paused or minimized, you might want to skip updating game logic entirely:
#include <SDL.h>
bool isPaused = false;
void updateGame(float deltaTime) {
// Game update logic here
}
int main() {
SDL_Init(SDL_INIT_VIDEO);
Uint64 previousTime = SDL_GetTicks64();
while (true) {
SDL_Event event;
while (SDL_PollEvent(&event)) {
if (event.type == SDL_WINDOWEVENT) {
if (event.window.event ==
SDL_WINDOWEVENT_MINIMIZED) {
isPaused = true;
} else if (event.window.event ==
SDL_WINDOWEVENT_RESTORED) {
isPaused = false;
// Reset the previous time
previousTime = SDL_GetTicks64();
}
}
}
if (!isPaused) {
Uint64 currentTime = SDL_GetTicks64();
float deltaTime = (currentTime -
previousTime) / 1000.0f;
updateGame(deltaTime);
previousTime = currentTime;
}
}
SDL_Quit();
return 0;
}By implementing these strategies, you can ensure that your game handles large time deltas gracefully, maintaining a smooth and consistent experience for players even when unexpected pauses or slowdowns occur.
Tick Rate and Time Deltas
Learn how to create smooth, time-aware game loops that behave consistently across different hardware configurations