Game Physics Engine Development, 2nd Edition

286 Chapter 12 Collision Detection

two objects, it should be added to the occupied list. Likewise, when we remove an

object from a cell, if the cell now contains just one object, it should be removed fro m

the list:

class Grid

{

// ... Previous code as before ...

std::vector<ObjectSet*> activeSets;

def add(Object* object)

{

unsigned location = getLocationIndex(object->center);

ObjectSet *set = locations + location;

if (set.size() == 1) activeSets.insert(set);

set.add(object);

}

def remove(Object* object)

{

unsigned location = getLocationIndex(object->center);

ObjectSet *set = locations + location;

if (set.size() == 2) activeSets.erase(set);

set.remove(object); ...