How to optimize game physics and collision detection in C++?

In order to optimize game physics, this article provides four techniques: 1) Space partitioning divides the world into smaller areas to quickly eliminate unnecessary collision checks; 2) Wide-phase collision detection uses proxy bodies for rough collision checks; 3 ) Lazy evaluation only performs collision detection when needed; 4) Multi-threading distributes collision detection tasks to multiple threads to improve concurrency. By applying these technologies, gaming performance can be significantly improved, resulting in a smoother experience.

C How to optimize game physics and collision detection

Optimizing game physics and collision detection is crucial to improving performance. This article will Provide some useful techniques and practical cases.

1. Space partitioning

Divide the game world into small areas (for example, grids or quadtrees), which can quickly exclude objects that do not need to be checked for collisions .

Practical case:

// 使用四叉树来管理游戏对象
QuadTree<GameObject> myQuadTree;

// 在游戏循环中更新四叉树
myQuadTree.Update(gameObjects);

// 对于每个需要检测碰撞的游戏对象
for (GameObject& obj : gameObjects) {
  // 获取对象的边界框
  AABB boundingBox = obj.GetBoundingBox();

  // 查找可能与 obj 碰撞的所有其他对象
  vector<GameObject*> potentialCollisions = myQuadTree.QueryRange(boundingBox);

  // 检查实际的碰撞
  for (GameObject* otherObj : potentialCollisions) {
    // ... 碰撞检查逻辑 ...
  }
}

2. Wide-phase collision detection

Before conducting expensive narrow-phase collision detection, Perform rough collision checking using a simple proxy body such as a sphere or AABB.

Practical case:

// 使用球体作为代理体
SphereCollider sphereCollider(obj.GetPosition(), obj.GetRadius());

// 对于每个需要检测碰撞的游戏对象
for (GameObject& obj : gameObjects) {

  // 更新代理体
  sphereCollider.SetPosition(obj.GetPosition());

  // 检查粗略碰撞
  for (SphereCollider& otherSphereCollider : otherColliders) {
    if (sphereCollider.Intersects(otherSphereCollider)) {
      // ... 狭相碰撞检查逻辑 ...
    }
  }
}

3. Lazy Evaluation

Only perform collision detection when really needed. For example, if the object is slower or farther away, detection can be skipped.

Practical case:

// 检查两个对象是否足够靠近以进行碰撞检测
float distanceSq = (obj1.GetPosition() - obj2.GetPosition()).LengthSquared();
float minDistanceSq = (obj1.GetRadius() + obj2.GetRadius()) * (obj1.GetRadius() + obj2.GetRadius());

if (distanceSq < minDistanceSq) {
  // ... 碰撞检查逻辑 ...
}

4. Multi-threading

If possible, distribute the collision detection task to multiple threads to improve concurrency.

Practical case:

// 创建线程池
ThreadPool threadPool(NumThreads);

// 对于每个需要检测碰撞的游戏对象
for (GameObject& obj : gameObjects) {
  // 创建任务并添加到线程池
  auto task = threadPool.AddTask([&obj]() {
    // ... 碰撞检查逻辑 ...
  });
}

// 等待所有任务完成
threadPool.WaitAllTasks();

By applying these technologies, game physics and collision detection performance can be significantly optimized to create a smoother and more responsive gaming experience.

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