Data Cart npm Package

Thu, 26 Jun 2025 22:14:57 UTC

I have a javascript/typescript module for packing arbitrary data into a cartridge that I use for a handful of my projects. I recently published it as an npm package as I thought it may be helpful to more people.

Below is an example cart where I used this package to quickly prepare a cart with a payload of polygonal shape data, followed by the script that was used to build it.
(The resulting p8 cart was exported as a png cart separately)

Use ◀️/▶️/🅾️/❎ to change shape.

p8_data_cart_example

by siwu

[Click to Play]

import { readFileSync, writeFileSync } from 'fs';
import { CartData, writeCart } from 'p8-data-cart';

const shapes = [
    // Square shape
    [

        -0.3, -0.3,
        0.3, -0.3,
        0.3, 0.3,
        -0.3, 0.3
    ],

    // Star shape
    [
        -0.33867, -0.11005,
        -0.07969, -0.11005,
        0.00000, -0.35553,
        0.07969, -0.11005,
        0.33867, -0.11005,
        0.12912, 0.04222,
        0.20885, 0.28781,
        0.00000, 0.13605,
        -0.20885, 0.28781,
        -0.12912, 0.04222
    ],
    // Heart shape
    [
        0.27532, -0.04442,
        0.25741, -0.01513,
        0.23889, 0.01376,
        0.21978, 0.04224,
        0.20008, 0.07030,
        0.17980, 0.09794,
        0.15894, 0.12513,
        0.13751, 0.15189,
        0.11553, 0.17819,
        0.09298, 0.20402,
        0.06990, 0.22938,
        0.04627, 0.25427,
        0.02210, 0.27866,
        0.01915, 0.28138,
        0.01593, 0.28362,
        0.01250, 0.28539,
        0.00891, 0.28668,
        0.00520, 0.28750,
        0.00144, 0.28783,
        -0.00234, 0.28768,
        -0.00608, 0.28706,
        -0.00973, 0.28595,
        -0.01324, 0.28435,
        -0.01657, 0.28227,
        -0.01966, 0.27970,
        -0.01975, 0.27962,
        -0.01983, 0.27953,
        -0.01992, 0.27945,
        -0.02001, 0.27936,
        -0.02010, 0.27927,
        -0.02019, 0.27919,
        -0.02027, 0.27910,
        -0.02036, 0.27901,
        -0.02044, 0.27893,
        -0.02053, 0.27884,
        -0.02062, 0.27875,
        -0.02070, 0.27866,
        -0.04491, 0.25428,
        -0.06860, 0.22940,
        -0.09174, 0.20404,
        -0.11433, 0.17821,
        -0.13637, 0.15191,
        -0.15785, 0.12516,
        -0.17875, 0.09796,
        -0.19909, 0.07032,
        -0.21884, 0.04226,
        -0.23800, 0.01377,
        -0.25656, -0.01512,
        -0.27452, -0.04442,
        -0.29418, -0.09758,
        -0.29962, -0.14669,
        -0.29277, -0.19072,
        -0.27559, -0.22866,
        -0.25001, -0.25950,
        -0.21800, -0.28221,
        -0.18148, -0.29578,
        -0.14242, -0.29919,
        -0.10275, -0.29142,
        -0.06443, -0.27146,
        -0.02939, -0.23829,
        0.00040, -0.19089,
        0.03020, -0.23829,
        0.06523, -0.27146,
        0.10355, -0.29142,
        0.14322, -0.29919,
        0.18228, -0.29578,
        0.21880, -0.28221,
        0.25082, -0.25950,
        0.27639, -0.22866,
        0.29357, -0.19072,
        0.30042, -0.14669,
        0.29499, -0.09758
    ]
];

function buildPayload(shapes: number[][]) {
    const payload: number[] = [];

    payload.push(shapes.length); // Shape count

    // Shape offset table
    let offset = 1 + shapes.length; // Shape count byte + offset table size
    for (const shapeData of shapes) {
        payload.push(offset);
        offset += 1 + shapeData.length; // 1 byte for point count + length of point data
    }

    // Shape point data
    for (const shapeData of shapes) {

        const pointCount = shapeData.length / 2;
        payload.push(pointCount);

        for (const shapePointComponent of shapeData) {
            // Center points around 0.5, 0.5 and scale range -1 - 1 to 0 - 255
            const ratio = (255 - 0) / (1 - -1)
            const centeredComponent = (shapePointComponent + 1);
            const scaledComponent = Math.round(centeredComponent * ratio);
            payload.push(scaledComponent);
        }
    }

    return new Uint8Array(payload);
}

const luaScript = readFileSync('shapes.lua', 'utf-8');
const payload = buildPayload(shapes);

const cartData = new CartData();
cartData.data.set(payload);
cartData.lua = luaScript;

const cartString = writeCart(cartData);
writeFileSync('shapes.p8', cartString);

Globbo

Tue, 15 Feb 2022 22:17:45 UTC

This is Globbo!

A PICO-8 adaptation of the classic Mac game Blobbo.

The goal of the game is to pick up all toy chests before proceeding to the next room through the stairs. Tread carefully though, or you might find yourself squished by a bowling ball or punctured by an arrow.

The game contains a subset of the features found in the original. Many of the rooms in this version have been inspired by the original. My approach for these rooms has been to try to make condensed versions of the originals, trying to capture the "theme" of a room while taking liberties with its layout to accommodate the 16x16 grid.

The aim was not to make a fully featured port of the original, but rather to pluck the best parts and reshape it in a way that works well with PICO-8.

Please enjoy! ^_^

Globbo 1.1

by siwu

[Click to Play]

Controls

D-pad / Arrow Keys: Move Globbo
Hold Cross / X + Circle / Z: Undo
Hold Cross / X + Up: Show play statistics

siwu [Lexaloffle Blog Feed]

Data Cart npm Package

Globbo

Controls

Changelog

Version 1.1

Version 1.0

Beta 0.5

Alpha 0.4

Alpha 0.3.1

Alpha 0.3

Alpha 0.2