@thi.ng/grid-iterators v4.0.111

This project is part of the @thi.ng/umbrella monorepo.

• About
  • Columns
  • Diagonal
  • Hilbert curve
  • Interleave columns
  • Interleave rows
  • Random
  • Rows
  • Outward spiral
  • Z-curve
  • Zigzag columns
  • Zigzag diagonal
  • Zigzag rows
  • Flood filling
  • Miscellaneous
  • Status
  • Related packages
• Installation
• Dependencies
• Usage examples
• API
• Authors
• License

About

2D grid and shape iterators w/ multiple orderings.

Provides the altogether 25 following orderings to generate grid coordinates, including iterators for shape rasterization, drawing, clipping, filling, processing in general:

Columns

Source

Also see the filtered version columnEnds2d(), which only includes the end points of each column.

Diagonal

Source

Also see the filtered version diagonalEnds2d(), which only includes the end points of the diagonals.

Hilbert curve

Source

Interleave columns

Source

Supports custom strides... example uses step = 4

Interleave rows

Source

Supports custom strides... example uses step = 4

Random

Source

Supports custom PRNG implementations via IRandom interface defined in @thi.ng/random

Rows

Source

Also see the filtered version rowEnds2d(), which only includes the end points of each row.

Outward spiral

Source

Z-curve

Source

Zigzag columns

Source

Zigzag diagonal

Source

Zigzag rows

Source

Some functions have been ported from Christopher Kulla's Java-based Sunflow renderer.

For more basic 2D/3D grid iteration, also see range2d() & range3d() in @thi.ng/transducers.

Flood filling

The floodFill() iterator can be used to iterate arbitrary 2D grids using an user-provided predicate function. The function recursively explores (in a row-major manner) the space in the [0,0]..(width,height) interval, starting at given x,y and continues as long given predicate function returns a truthy value. Any eligible 90-degree connected regions will be found and iterated recursively. The predicate function is used to select eligible grid cells (e.g. "pixels" of sorts).

// source "image"
const img = [
    "█", " ", " ", " ", "█",
    "█", " ", "█", " ", " ",
    " ", " ", "█", " ", "█",
    " ", "█", "█", " ", " ",
    " ", " ", " ", "█", "█",
];

// flood fill iterator from point (1,0)
// only accept " " as source pixel value
// image size is 5x5
const region = floodFill((x, y) => img[x + y * 5] === " ", 1, 0, 5, 5);

// label filled pixels using increasing ASCII values
let ascii = 65; // "A"
for(let [x,y] of region) img[x + y * 5] = String.fromCharCode(ascii++);

// result image showing fill order
img
// [
//   "█", "A", "B", "C", "█",
//   "█", "I", "█", "D", "E",
//   "K", "J", "█", "F", "█",
//   "L", "█", "█", "G", "H",
//   "M", "N", "O", "█", "█"
// ]

Miscellaneous

Additionally, the following shape iterators are available, all also with optional clipping:

• circle (Bresenham)
• hline
• vline
• line (Bresenham)

Status

STABLE - used in production

Search or submit any issues for this package

Related packages

• @thi.ng/morton - Z-order curve / Morton encoding, decoding & range extraction for arbitrary dimensions
• @thi.ng/rasterize - 2D shape drawing & rasterization
• @thi.ng/transducers - Lightweight transducer implementations for ES6 / TypeScript

Installation

yarn add @thi.ng/grid-iterators

ES module import:

<script type="module" src="https://cdn.skypack.dev/@thi.ng/grid-iterators"></script>

Skypack documentation

For Node.js REPL:

# with flag only for < v16
node --experimental-repl-await

> const gridIterators = await import("@thi.ng/grid-iterators");

Package sizes (gzipped, pre-treeshake): ESM: 2.08 KB

Dependencies

• @thi.ng/api
• @thi.ng/arrays
• @thi.ng/binary
• @thi.ng/bitfield
• @thi.ng/morton
• @thi.ng/random
• @thi.ng/transducers

Usage examples

Several demos in this repo's /examples directory are using this package.

A selection:

API

Generated API docs

import * as gi from "@thi.ng/grid-iterators";

[...gi.zigzagRows2d(4, 4)]

// [
//   [ 0, 0 ], [ 1, 0 ], [ 2, 0 ], [ 3, 0 ],
//   [ 3, 1 ], [ 2, 1 ], [ 1, 1 ], [ 0, 1 ],
//   [ 0, 2 ], [ 1, 2 ], [ 2, 2 ], [ 3, 2 ],
//   [ 3, 3 ], [ 2, 3 ], [ 1, 3 ], [ 0, 3 ]
// ]

Authors

Karsten Schmidt

If this project contributes to an academic publication, please cite it as:

@misc{thing-grid-iterators,
  title = "@thi.ng/grid-iterators",
  author = "Karsten Schmidt",
  note = "https://thi.ng/grid-iterators",
  year = 2019
}

License

© 2019 - 2021 Karsten Schmidt // Apache Software License 2.0