To get started with game development I purchased some top-down sprite assets which come arranged in a grid, but to use them with a typical 2D rendering engine (I'm using Pixi.JS), I need a JSON file tracking the coordinates and dimensions of the grid the assets are arranged onto (which was not included in the package I purchased).
So I bought a license for TexturePacker thinking I would be able to somehow generate that JSON. I suppose I could write a program that generates the JSON file (since I do know the assets grid size for the PNG) but I'm wondering if I'm missing some easier way.
The thing is, I purchased probably ten different assets packs and most of them include many of their assets in a plain PNG grid layout with no JSON file tracking the dimensions of the grid. So it seems like a normal format. So I'm perplexed by the idea of having to manually separate the grid into separate PNG assets to then feed it to TexturePacker to re-combine the assets into a grid.
Is there an easier way?