In Java (Swing), say I've got a 2D game where I have various types
of entities on the screen, such as a player, bad guys, powerups, etc. When the player moves across the screen, in order to do efficient checking
of what is in the immediate vicinity
of the player, I would think I'd want indexed access to the things that are near the character based on their position.
For example, if player 'P' steps onto element 'E' in the following example...
| | | | | |
| | | |P| |
| | |E| | |
| | | | | |
... would be to do something like:
if(player.getPosition().x == entity.getPosition().x &&
entity.getPosition.y == thing.getPosition().y)
{
//do something
}
And thats fine, but that implies that the entities hold their positions, and therefor if I had MANY entities on the screen I would have to loop through all possible entities available and check each ones position against the player position. This seems really inefficient especially if you start getting tons
of entities.
So, I would suspect I'd want some sort
of map like
Map<Point, Entity> map = new HashMap<Point, Entity>();
And store my
point information there, so that I could access these entities in constant time. The only problem with that approach is that, if I want to move an entity to a different
point on the screen, I'd have to search through the values
of the HashMap for the entity I want to move (inefficient since I dont know its
Point position ahead
of time), and then once I've found it remove it from the HashMap, and re-insert it with the new position information.
Any suggestions or advice on what sort
of data structure / storage format I ought to be using here in order to have efficient access to Entities based on their position, as well as Position's based on the Entity?
