Optimizing tests by getting only entities nearby

When performing collision, intersection or proximity tests it is better to perform those tests, which commonly involve lots of processing, only on entities that are in the buckets nearby the object's location. It avoids having to perform expensive tests on entities that are too far.

Functions like GetEntitiesAroundBucket or GetEntitiesAroundEntity seek entities in the area. Sample:

vector2 bombPos(200.0f, 300.0f);
vector2 bombBucket = GetBucket(bombPos);  
ETHEntityArray entities;

// Copies into 'entities' a handle to each entity contained in the buckets around 'bombBucket'
GetEntitiesAroundBucket(bombBucket, entities);

for (uint t = 0; t < entities.Size(); t++)
    print(entities[t].GetEntityName() + " is around the bomb! Careful!");