resize the tileset used by a tiled map, preserving the col, row locations

resize-tiled-map.js

let level = require('./level.js')


// given a tiled level that references a tileset of certain dimensions, update to a tileset of different dimensions

let idx = -1

const locations = [ ]

do {
    idx = level.indexOf('<data encoding="csv">', idx+1)
    if (idx > 0)
        locations.push(idx)
} while(idx > 0)

const originalTilesetColumns = 15
const newTilesetColumns = 120

while (locations.length) {
    const startIdx = locations.pop() + 21
    const endIdx = level.indexOf('</data>', startIdx)

    // everything in the level up to the data set
    const pre = level.substring(0, startIdx+1)

    // the data set
    const rawData = level.substring(startIdx, endIdx)

    const data = rawData
                      .trim()
                      .split(',')
                      .map((raw) => parseInt(raw.trim(), 10))
                      .map((cell) => {
                          // 0 means no tile set
                          if (cell === 0)
                              return 0

                          // cells are not 0 based, they are 1 based
                          cell--

                          const col = cell % originalTilesetColumns
                          const row = Math.floor(cell / originalTilesetColumns)

                          const newCell = (row * newTilesetColumns) + col

                          return newCell + 1
                      }).join(',')

    // everything after the data set
    const post = level.substring(endIdx)

    level = pre + data + post
}

console.log(level.trim())