ennea-tree

Immutable tilemap quad-tree with support for mega-tiles

Installation

npm install --save ennea-tree

Usage

import * as enneaTree from 'ennea-tree'

let tree = enneaTree.createTree(16);
tree = enneaTree.set(tree, 'hello', {top:0, left:0});
tree = enneaTree.set(tree, 'hi', {top:4, left:7, width:3, height:5});
for(const fruit of enneaTree.getIterator(tree, {top:0, left:0, width:16, height:16})){
    console.log(fruit);
}

Methods

enneaTree.get(tree, top, left)

Get the data at the position, or null.

// returns
{
    data,
    top,
    left,
    width,
    height
}

enneaTree.set(tree, data, {top, left, width=1, height=1, right=left+width, bottom=top+height})

Set the data at the position or area. Specify either the width/height or right/bottom. Returns the modified tree. If the area is not empty, returns the original tree.

See also setUnsafe, which does not check if the area is empty before setting, and can therefore result in corrupted data.

enneaTree.diff(treeBefore, treeAfter)

Get the differences between two trees. This is a generator, you can use for of to loop through the changes.

// returns
{
    type: SET,
    top,
    left,
    width,
    height,
    after
}

{
    type: UPDATE,
    top,
    left,
    width,
    height,
    before,
    after
}

{
    type: CLEAR,
    top,
    left,
    width,
    height,
    before
}

enneaTree.clear(tree, {top, left, width=1, height=1, right=left+width, bottom=top+height})

Clear the position or area. Returns the modified tree.

See also clearUnsafe, which returns null if the tree becomes empty.

enneaTree.update(tree, (before, context, {top, left}) => after)

Update multiple positions in a tree without creating intermediate tree structures.

const updater = enneaTree.update(tree, (before, context, {top, left}) => before+context);
updater.update({0, 0}, 10);
tree = updater.result([
    {area: {1, 1}, context: 5},
    {area: {1, 2}, context: 5},
    {area: {1, 3}, context: 5}
]);

Note: updater.result takes an array that can be used as a queue. You can push changes onto this queue from the update callback.

enneaTree.getAll(tree, {top, left, width=1, height=1, right=left+width, bottom=top+height})

Get all the data within the area as an array. This is a convenience method that uses getIterator.

// returns
[{
    data,
    top,
    left,
    width,
    height
}]

enneaTree.isEmpty(tree, {top, left, width=1, height=1, right=left+width, bottom=top+height})

Check if the area is empty, ie, if getAll returns an empty array.

enneaTree.setUnsafe(tree, data, , {top, left, width=1, height=1, right=left+width, bottom=top+height})

This method can result in corrupted trees.

See set.

enneaTree.createNode(size=1)

returns a new empty node with the specified size.

enneaTree.clearUnsafe()

This method will return null if the tree is empty after clearing

See clear.

enneaTree.getIterator(tree, {top, left, width=1, height=1, right=left+width, bottom=top+height})

Get all the data within the area as an iterator, than can be looped over with a for of loop.

// returns
{
    data,
    top,
    left,
    width,
    height
}

enneaTree.createTree(size=1)

See createNode.

Constants

enneaTree.SET

'set'

enneaTree.UPDATE

'update'

enneaTree.CLEAR

'clear'