Awesome
simple-quadtree
simple-quadtree
is a minimal quadtree implementation that supports simple put
, get
, remove
and clear
operations on objects having a x, y
position and w, h
dimension.
Installation
npm install simple-quadtree
Should also work in all browsers as is. simple-quadtree
has no dependencies.
Usage
Create a quadtree by giving it some bounds, e.g. x, y, width and height
var QuadTree = require('simple-quadtree');
var qt = QuadTree(0, 0, 100, 100);
You can also give QuadTree
some options; currently, the only option is the maximum number of children in a quadtree node until it is subdivided:
var qt = QuadTree(0, 0, 100, 100, { maxchildren: 25 }); // defaults to 25
Putting objects
Put objects into the quadtree by using put
. The objects can be anything as long as they have x, y, w, h
properties as numbers indicating the bounding area of that object:
qt.put({x: 5, y: 5, w: 0, h: 0, string: 'test'});
Each w
and h
property must be nonnegative.
Getting objects
Iterate over the objects by giving an area and a callback:
qt.get({x:0, y: 0, w: 10, h: 10}, function(obj) {
// obj == {x: 5, y: 5, w: 0, h: 0, string: 'test'}
});
Iterating over objects continues as long as there are remaining objects and the callback function returns true
. If the callback does not return true
, the iteration is interrupted.
Alternatively you can omit the callback to return an array of all matching objects:
var result = qt.get({x:0, y: 0, w: 10, h: 10});
// result == [{x: 5, y: 5, w: 0, h: 0, string: 'test'}]
You can also give a buffer threshold, indicating that you want to iterate over all objects in the area expanded by the threshold to all directions:
qt.get({x:0, y: 0, w: 4, h: 4}, 2, function(obj) {
// obj == {x: 5, y: 5, w: 0, h: 0, string: 'test'}
});
Alternatively, you can also iterate over all objects that are close to a line segment. The line segment is defined by having x, y, dx, dy, dist
properties:
qt.get({x: 0, y: 0, dx: 1, dy: 1}, 1, function(obj) {
// obj == {x: 5, y: 5, w: 0, h: 0, string: 'test'}
});
Please note it is assumed that dx, dy
are a 2-d vector normalized to the length of 1. The dist
property of the object tells the length of the line segment to this direction. If dist
is undefined or negative, it is assumed to be an infinite line instead of a line segment.
Please also note that getting objects close to a line segment will guarantee that all objects close to the line will be iterated over, but other non-overlapping objects may also be returned.
You can also use a buffer threshold when iterating based on a line segment.
Modifying objects
In order to remove or update an object already in the quadtree, you have to identify the object. By default, update
and remove
affect all objects with x, y, w, h
identical to the passed object.
If you want to remove only a specific object, you can should pass the name of the uniquely identifying property to update
and remove
.
Updating objects
If the coordinates of an object already put into the quadtree change, you should call update
to make sure it is still indexed in the right location:
var obj = { x: 5, y: 5, w: 0, h: 0, string: 'test', id: 4233 };
qt.put(obj);
assert(obj.x == 5);
qt.update(obj, 'id', { x: 10 }); // change obj.x to 10
assert(obj.x == 10);
Call to update
also modifies the coordinates of the object to be updated, and returns true
if the object was correctly updated and false
if the object to be updated was not found.
Please note that despite passing 'id'
as the identifying attribute, the object passed to update
must still have the same x, y, w, h
properties as the original inserted object. update
traverses the tree similarly as put
, so if these properties are not the same, it is possible that the object to be updated is not found.
Removing objects
To remove objects, call remove
with the original object that was passed to put
:
var obj = { x: 5, y: 5, w: 0, h: 0, string: 'test', id: 4233 };
qt.put(obj);
qt.remove(obj); // remove all objects with matching coordinates
var obj1 = { x: 5, y: 5, w: 0, h: 0, string: 'test', id: 4233 };
var obj2 = { x: 5, y: 5, w: 0, h: 0, string: 'test', id: 4234 };
qt.put(obj1);
qt.put(obj2);
// remove by uniquely identifying attribute
qt.remove(obj1, 'id'); // only obj1 removed
qt.remove(obj1); // obj2 removed
Please note that despite passing 'id'
as the identifying attribute, the object passed to put
must still have the same x, y, w, h
properties as the object to be removed. remove
traverses the tree similarly as put
, so if these properties are not the same, it is possible that the object to be removed is not found.
Clearing the quadtree
To clear the quadtree call clear:
qt.clear();
This creates a new root node effectively putting the existing one up for garbage collection.
License
(The MIT License)
Copyright (c) 2013 Antti Saarinen <antti.p.saarinen@gmail.com>
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.