%% title = "tairu - an interactive exploration of 2D autotiling techniques"
   scripts = ["tairu/tiling-demo.js", "tairu/tairu.js"]

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- I remember since my early days doing programming, I've been interested in how games like Terraria handle automatically tiling their terrain.

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    - in Terraria, you can fully modify the terrain however you want, and the tiles will connect to each other seamlessly.

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        - TODO: short videos demoing this here

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- once upon a time I heard of a technique called *bitwise autotiling*

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    + I learned about it back when I was building 2D Minecraft clones using [Construct 2](https://www.construct.net/en/construct-2/manuals/construct-2), and I wanted my terrain to look nice as it does in Terraria

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        - Construct 2 was one of my first programming experiences and the first game engine I truly actually liked :smile:

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    - this technique involves assigning the cardinal directions (north, south, east, west) to a bitset.
    then for each tile you look at which adjacent tiles should be connected to

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        - this connection condition can be whatever you want - in most cases it's just "is the adjacent tile of the same type as the current tile?"

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            - for example, "is the tile to the left a dirt tile?"

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    - and then you use this bitset to index into a lookup table of tiles

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        - for example, say we have the following grid of tiles:\
        TODO editable grid on javascript

        for each tile, we can assign a bitset of cardinal directions like so:\
        TODO grid linked with the other grid to show which adjacent tiles each tile connects to

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    - in JavaScript it would look something like this:
    ```javascript
    // TODO code example
    ```

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- bitwise autotiling is a really cool technique that I've used in plenty of games in the past

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    - as I mentioned before, [I've known it since my Construct 2 days][branch:01HPD4XQPW6VK3FDW5QRCE6HSS], but when it comes to my released games [Planet Overgamma] would probably be the first to utilize it properly

    TODO video of some Planet Overgamma gameplay showing the autotiling in action

    [Planet Overgamma]: https://liquidev.itch.io/planet-overgamma-classic

        - this accursed game has been haunting me for years since; there have been many iterations.
        he autotiling source code of the one in the video can be found [here][autotiling source code].

        [autotiling source code]: https://github.com/liquidev/planet-overgamma/blob/classic/jam/map.lua#L209

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+ but one day I found a really cool project called [Tilekit](https://rxi.itch.io/tilekit)

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    + (of course it's really cool, after all rxi made it)

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        - for context rxi is the genius behind the Lua-powered, simple, and modular text editor `lite` that I was using for quite a while

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            - after a while I switched to a fork - Lite XL, which had better font rendering and more features

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            - I stopped using it because VS Code was just more feature packed and usable; no need to reinvent the wheel, rust-analyzer *just works.*

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                - the LSP plugin for Lite XL had some issues around autocompletions not filling in properly :pensive:\
                it's likely a lot better now, but back then I decided this is too much for my nerves.
                while tinkering with your editor is something really cool, in my experience it's only cool up to a point.

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- the cool thing with Tilekit is that it's *more* than just your average bitwise autotiling - of course it *can* do basic autotiling, but it can also do so much more

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    - if I had to describe it, it's basically something of a *shader langauge for tilesets.* this makes it really powerful, as you can do little programs like

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        - autotile using this base tileset

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        - if the tile above is empty AND with a 50% chance

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            - then grass

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        - if the tile above is solid AND with a 10% chance

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            - then vines

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        - if the tile above is vines AND with a 50% chance

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            - then vines

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    - I mean, after all - bitwise autotiling is basically a clever solution to an `if` complexity problem, so why not extend that with more logic and rules and stuff to let you build more complex maps?

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- ever since then I've been wanting to build something just like Tilekit, but in the form of an educational, interactive blog post to demonstrate the ideas in a fun way

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    - and what you're reading is the result of that.

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- so let's get going! first, we'll build a basic tile editor using JavaScript.

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    + not my favorite language, but we're on the Web so it's not like we have much more of a choice.

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        - I could use TypeScript, but this page follows a philosophy of not introducing complexity where I can deal without it.
        TypeScript is totally cool, but not necessary.

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    - I'll be using Web Components (in particular, custom elements) combined with canvas to add stuff onto the page.