Optimizing Ticking for Large Object Counts
How can we optimize ticking for a large number of objects without sacrificing performance?
Optimizing ticking for a large number of objects is crucial for maintaining good performance in complex games. Here are several strategies to achieve this.
Object Pooling
Instead of creating and destroying objects frequently, use an object pool to reuse inactive objects.
#include <queue>
#include <vector>
template <typename T>
class ObjectPool {
public:
ObjectPool(size_t initialSize) {
for (size_t i = 0; i < initialSize; ++i) {
objects.emplace_back(
std::make_unique<T>());
available.push(&(*objects.back()));
}
}
T* Get() {
if (available.empty()) {
objects.emplace_back(
std::make_unique<T>());
available.push(&(*objects.back()));
}
T* obj = available.front();
available.pop();
return obj;
}
void Return(T* obj) { available.push(obj); }
private:
std::vector<std::unique_ptr<T>> objects;
std::queue<T*> available;
};
class Bullet : public GameObject {
// Bullet implementation
};
class BulletManager {
public:
BulletManager() : pool(1000) {}
void SpawnBullet() {
Bullet* bullet = pool.Get();
activeBullets.push_back(bullet);
}
void TickAll() {
for (
auto it = activeBullets.begin();
it != activeBullets.end();
) {
if ((*it)->IsActive()) {
(*it)->Tick();
++it;
} else {
pool.Return(*it);
it = activeBullets.erase(it);
}
}
}
private:
ObjectPool<Bullet> pool;
std::vector<Bullet*> activeBullets;
};Spatial Partitioning
Use spatial partitioning techniques like quadtrees or grid systems to only update objects that are relevant to the current game state.
#include <unordered_map>
class GridCell {
public:
void AddObject(GameObject* obj) {
objects.push_back(obj);
}
void RemoveObject(GameObject* obj) {
objects.erase(
std::remove(objects.begin(),
objects.end(), obj),
objects.end());
}
void TickAll() {
for (auto* obj : objects) { obj->Tick(); }
}
private:
std::vector<GameObject*> objects;
};
class SpatialGrid {
public:
void AddObject(
GameObject* obj, int x, int y
) {
int cellX = x / cellSize;
int cellY = y / cellSize;
grid[{cellX, cellY}].AddObject(obj);
}
void TickAll() {
for (auto& [pos, cell] : grid) {
cell.TickAll();
}
}
private:
std::unordered_map<
std::pair<int, int>, GridCell> grid;
int cellSize{100}; // Size of each grid cell
};Multithreading
Utilize multiple threads to update objects in parallel.
#include <mutex>
#include <thread>
class World {
public:
void TickAll() {
const size_t numThreads =
std::thread::hardware_concurrency();
std::vector<std::thread> threads;
for (size_t i = 0; i < numThreads; ++i) {
threads.emplace_back(
[this, i, numThreads](){
for (size_t j = i; j < objects.size();
j += numThreads) {
objects[j]->Tick();
}
});
}
for (auto& thread : threads) {
thread.join();
}
}
private:
std::vector<std::unique_ptr<GameObject>>
objects;
std::mutex objectsMutex;
};Data-Oriented Design
Organize data for cache-friendly access patterns.
class ComponentSystem {
public:
void AddObject(int x, int y, float velocity) {
positions.emplace_back(x, y);
velocities.push_back(velocity);
}
void TickAll() {
for (
size_t i = 0;
i < positions.size();
++i
) {
positions[i].x += velocities[i];
positions[i].y += velocities[i];
}
}
private:
struct Position {
int x, y;
};
std::vector<Position> positions;
std::vector<float> velocities;
};Lazy Evaluation
Only update objects when their state is actually needed.
class LazyGameObject {
public:
void SetNeedsUpdate() { needsUpdate = true; }
void Tick() {
if (needsUpdate) {
DoUpdate();
needsUpdate = false;
}
}
private:
bool needsUpdate{false};
void DoUpdate() {
// Perform actual update logic
}
};Update Frequency Management
Allow different update frequencies for different types of objects.
class GameObject {
public:
GameObject(int updateFrequency) :
updateFrequency(updateFrequency) {}
void Tick(int currentFrame) {
if (currentFrame % updateFrequency == 0) {
DoTick();
}
}
private:
int updateFrequency;
virtual void DoTick() = 0;
};By implementing these optimization techniques, you can significantly improve the performance of your game when dealing with a large number of objects.
Remember to profile your game to identify bottlenecks and apply these optimizations where they'll have the most impact.
Ticking
Using Tick() functions to update game objects independently of events