Awesome

QuadtreeSprite Starling extension

About

QuadtreeSprite is a Starling extensions which is useful when you need a container for large amount of children DisplayObjects which are usually not visible on the screen at the same time. Perfect use-case: Large 2D world map.

There are a few things different in the API so check the usage section below.

The example creates 100,000 Quad objects on 20,000 x 20,000 world, which results in the following performance on my machine:

• Sprite - 0.9 FPS (Not really designed for this :) )
• QuadtreeSprite - 60 FPS

Demo

You can check out the demo and introduction at: http://justpinegames.com/blog/2013/03/quadtreesprite/

Usage

Creation:

// Define the world bounds, if objects is outside them it will always be displayed
var worldBounds:Rectangle = new Rectangle(...);
var container:QuadtreeSprite = new QuadtreeSprite(worldBounds);

Adding/Removing children:

// Same as in Starling:
container.addChild(new Quad(...));
container.removeChild(...);

Important to note is that you have to explicitly update object when it's position or size has changed!

var object:Quad = ...;
container.addChild(object);
object.x = 10;
container.updateChild(object);

To change the visible portion of the scene use visibleViewport, everything outside that rectangle will be removed from display list:

container.visibleViewport = new Rectangle(...);

When visible objects change you can listen to Event.CHANGE, you should sort here if you need your objects to be in order:

container.addEventListener(Event.CHANGE, ...);

You can iterate through the currently visible objects, or all of which the container holds:

// visible objects
for (var i:int = 0; i < container.numChildren; ++i) {
    var object:DisplayObject = container.getChildAt(i);
}

// all objects
for (var i:int = 0; i < container.dynamicNumChildren; ++i) {
    var object:DisplayObject = container.dynamicGetChildAt(i);
}

Note! Order of insertion is not maintained by default, as it has a performance cost. You can enable it when creating an object:

var container:QuadtreeSprite = new QuadtreeSprite(worldBounds, true);