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    @thi.ng/grid-iterators
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    2.3.24 • Public • Published

    grid-iterators

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

    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

    anim

    Source

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

    Diagonal

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

    Hilbert curve

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    Source

    Interleave columns

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    Source

    Supports custom strides... example uses step = 4

    Interleave rows

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    Supports custom strides... example uses step = 4

    Random

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

    Rows

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

    Outward spiral

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    Z-curve

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    Zigzag columns

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    Zigzag diagonal

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    Zigzag rows

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    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:

    Status

    STABLE - used in production

    Search or submit any issues for this package

    Related packages

    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 (brotli'd, pre-treeshake): ESM: 2.19 KB

    Dependencies

    Usage examples

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

    A selection:

    Screenshot Description Live demo Source
    Visualization of different grid iterator strategies Demo Source

    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 - 2022 Karsten Schmidt // Apache Software License 2.0

    Install

    npm i @thi.ng/grid-iterators

    DownloadsWeekly Downloads

    180

    Version

    2.3.24

    License

    Apache-2.0

    Unpacked Size

    67.3 kB

    Total Files

    48

    Last publish

    Collaborators

    • thi.ng