img2brs/src/img2brs.js

Converts images to Brickadia save files (.brs)

import brs from 'brs-js';
import { SIMPLE_DIRECTION_MAP, DEFAULT_DESCRIPTION } from './constants';
import { getSaveTime, srgbToLinear } from './utils';

/**
 * Converts inputted File into a .brs Blob
 *
 * @param {ImageBitmap} file - User uploaded image as ImageBitmap
 * @param {String} options.brick - value in BRICKS
 * @param {String} options.material - value in MATERIALS
 * @param {[Number, Number, Number]} options.size
 * @returns {Blob} representing a .brs file
 */
export default function img2brs(file, options) {
  const {
    brick,
    material,
    size,
    simpleDirection,
    description,
  } = options;

  const img = file;

  const canvas = new OffscreenCanvas(img.width, img.height);
  const ctx = canvas.getContext('2d');
  ctx.drawImage(img, 0, 0);

  const imageData = ctx.getImageData(0, 0, canvas.width, canvas.height);
  const pixels = imageData.data;

  const bricks = [];
  for (let x = 0; x < canvas.width; x++) {
    for (let y = 0; y < canvas.height; y++) {
      const index = (y * canvas.width + x) * 4;
      const pixelRgba = {
        r: pixels[index],
        g: pixels[index + 1],
        b: pixels[index + 2],
        a: pixels[index + 3]
      };

      if (pixelRgba.a > 0) {
        bricks.push(pixelToBrick(x, y, pixelRgba, size, simpleDirection, canvas.height));
      }
    }
  }

  const writeData = {
    description: description || DEFAULT_DESCRIPTION,
    save_time: getSaveTime(),
    brick_assets: [brick],
    materials: [material],
    bricks,
  };

  return new Blob([brs.write(writeData)]);
}

/**
 * Converts image pixel and a few options into a Brick object
 * @param {Number} x - pixel x-coordinate in image
 * @param {Number} y - pixel y-coordinate in image
 * @param {RGBA} pixelRgba
 * @param {[Number, Number, Number]} size
 * @param {string} simpleDirection - 'vertical' or 'horizontal'
 * @param {Number} imgHeight
 * @returns {Brick}
 */
function pixelToBrick(x, y, pixelRgba, size, simpleDirection, imgHeight) {
  const { r, g, b, a } = pixelRgba;
  const isVertical = simpleDirection === 'vertical';

  // Calculations taken from the original img2brs by mraware
  const newX = isVertical ? x * size[1] * 2 + size[1] : x * size[0] * 2 + size[0];
  const newY = isVertical ? y * size[0] * 2 + size[0] : y * size[1] * 2 + size[1];
  const position = isVertical ? [newX, size[2], -newY + (imgHeight * size[0] * 2)] : [newX, newY, size[2]];

  return {
    color: [srgbToLinear(r), srgbToLinear(g), srgbToLinear(b), a],
    size,
    direction: SIMPLE_DIRECTION_MAP[simpleDirection],
    position,

    asset_name_index: 0, // always zero because brick_assets array in save file will only consist of the selected brick
    material_index: 0,  // always zero because materials array in save file will only consist of the selected brick
    rotation: 0,
    collision: true,
    visibility: true,
  };
}