/**
* Given a pointer to an entity and a std container of pointers to nearby entities, this function
* checks to see if there is an overlap between entities. If there is, then the entities are moved
* away from each other
*/
public static <T extends BaseGameEntity, conT extends List<? extends BaseGameEntity>>
void EnforceNonPenetrationContraint(T entity, final conT others) {
ListIterator<? extends BaseGameEntity> it = others.listIterator();
// iterate through all entities checking for any overlap of bounding
// radii
while (it.hasNext()) {
BaseGameEntity curOb = it.next();
// make sure we don't check against this entity
if (curOb == entity) {
continue;
}
// calculate the distance between the positions of the entities
Vector2D ToEntity = sub(entity.Pos(), curOb.Pos());
double DistFromEachOther = ToEntity.Length();
// if this distance is smaller than the sum of their radii then this
// entity must be moved away in the direction parallel to the
// ToEntity vector
double AmountOfOverLap = curOb.BRadius() + entity.BRadius() - DistFromEachOther;
if (AmountOfOverLap >= 0) {
// move the entity a distance away equivalent to the amount of overlap.
entity.SetPos(add(entity.Pos(), mul(div(ToEntity, DistFromEachOther), AmountOfOverLap)));
}
} // next entity
}
/**
* tags any entities contained in a std container that are within the radius of the single entity
* parameter
*/
public static <T extends BaseGameEntity, conT extends List<? extends T>> void TagNeighbors(
T entity, conT others, final double radius) {
ListIterator<? extends T> it = others.listIterator();
// iterate through all entities checking for range
while (it.hasNext()) {
T curOb = it.next();
// first clear any current tag
curOb.UnTag();
// work in distance squared to avoid sqrts
Vector2D to = sub(curOb.Pos(), entity.Pos());
// the bounding radius of the other is taken into account by adding it
// to the range
double range = radius + curOb.BRadius();
// if entity within range, tag for further consideration
if ((curOb != entity) && (to.LengthSq() < range * range)) {
curOb.Tag();
}
} // next entity
}
