四叉树的js实现

基于

https://gamedevelopment.tutsplus.com/tutorials/quick-tip-use-quadtrees-to-detect-likely-collisions-in-2d-space--gamedev-374

quadtree-js

This is a JavaScript Quadtree implementation of the Java Methods described in this tutorial:http://gamedev.tutsplus.com/tutorials/implementation/quick-tip-use-quadtrees-to-detect-likely-collisions-in-2d-space/

This is not a collision engine, but an algorithm to narrow down objects of possible collision.

Please read the tutorial if you want to know more about Quadtrees.

There are two examples: simple and dynamic.

• red squares represent Quadtree Nodes
• empty white squares represent objects in our Quadtree
• the cursor is the area we constantly test for
• objects turned green are candidates for collision, returned from the receive-function

How to use

Create a new Quadtree with default values for max_objects (10) and max_levels (4)

var myTree = new Quadtree({
	x: 0,
	y: 0,
	 400,
	height: 300
});

If you want to specify max_objects and max_levels on your own, you can pass them as a 2nd and 3rd argument

var myTree = new Quadtree({
	x: 0,
	y: 0,
	 800,
	height: 600
}, 5, 8);

Insert an element in the Quadtree

myTree.insert({
	x : 200,
	y : 150,
	width : 20,
	height : 20
});

Retrieve elements that "collide" with the given bounds

var elements = myTree.retrieve({
	x : 150,
	y : 100,
	width : 20,
	height : 20
});

Clear the Quadtree

myTree.clear();

Check out the examples for more information. Feel free to open an issue if you have any problems.

There is an alternative quadtree-js hitman branch available that allows you to update and remove single objects. This can be handy when most of the objects in your Quadtree are static.