294 lines
15 KiB
Plaintext
294 lines
15 KiB
Plaintext
%% title = "tairu - an interactive exploration of 2D autotiling techniques"
|
|
scripts = [
|
|
"tairu/cardinal-directions.js",
|
|
"tairu/framework.js",
|
|
"tairu/tairu.js",
|
|
"tairu/tilemap-registry.js",
|
|
]
|
|
styles = ["tairu.css"]
|
|
|
|
% id = "01HPD4XQPWM8ECT2QM6AT9YRWB"
|
|
- I remember since my early days doing programming, I've been interested in how games like Terraria handle automatically tiling their terrain.
|
|
|
|
% id = "01HPD4XQPWPDBH6QQAZER7A05G"
|
|
- in Terraria, you can fully modify the terrain however you want, and the tiles will connect to each other seamlessly.
|
|
|
|
% id = "01HPD4XQPW8HE7681P7H686X4N"
|
|
- TODO: short videos demoing this here
|
|
|
|
% id = "01HPD4XQPWJBTJ4DWAQE3J87C9"
|
|
- once upon a time I heard of a technique called...\
|
|
**bitwise autotiling**
|
|
|
|
% id = "01HPD4XQPW6VK3FDW5QRCE6HSS"
|
|
+ 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
|
|
|
|
% id = "01HPD4XQPWJ1CE9ZVRW98X7HE6"
|
|
- Construct 2 was one of my first programming experiences and the first game engine I truly actually liked :smile:
|
|
|
|
% id = "01HPJ8GHDET8ZGNN0AH3FWA8HX"
|
|
- let's begin with a tilemap. say we have the following grid of tiles: (the examples are interactive, try editing it!)
|
|
|
|
<canvas
|
|
is="tairu-editor"
|
|
data-tilemap-id="bitwiseAutotiling"
|
|
data-tile-size="40">
|
|
Your browser does not support <canvas>.
|
|
</canvas>
|
|
|
|
% id = "01HPJ8GHDEC0Z334M04MTNADV9"
|
|
- for each tile, we can assign a bitset of cardinal directions like so:
|
|
|
|
<canvas
|
|
is="tairu-editor-cardinal-directions"
|
|
data-tilemap-id="bitwiseAutotiling"
|
|
data-tile-size="40">
|
|
Your browser does not support <canvas>.
|
|
</canvas>
|
|
|
|
% template = true
|
|
id = "01HPJ8GHDE9QKQ4QFZK1Z1KQD4"
|
|
classes.branch = "tileset-cardinal-directions-demo"
|
|
+ now given a tileset, such as the one below that I drew a while ago, we can assign each tile to a set of cardinal directions.
|
|
I'll indicate where there's a connection between individual tiles with the letters **N**, **E**, **S**, **W**, standing for the cardinal directions **N**orth, **E**ast, **S**outh, and **W**est.
|
|
|
|
<ul class="tileset-demo">
|
|
<li class="full-image">
|
|
<img alt="a 16-tile tileset of 8x8 pixel metal" src="{% pic 01HPHVDRV0F0251MD0A2EG66C4 %}">
|
|
</li>
|
|
<li class="tileset-pieces">
|
|
<span class="metal x-0 y-0"><span class="east">E</span><span class="south">S</span></span>
|
|
<span class="metal x-1 y-0"><span class="east">E</span><span class="south">S</span><span class="west">W</span></span>
|
|
<span class="metal x-2 y-0"><span class="south">S</span><span class="west">W</span></span>
|
|
<span class="metal x-3 y-0"><span class="south">S</span></span>
|
|
<span class="metal x-0 y-1"><span class="east">E</span><span class="south">S</span><span class="north">N</span></span>
|
|
<span class="metal x-1 y-1"><span class="east">E</span><span class="south">S</span><span class="west">W</span><span class="north">N</span></span>
|
|
<span class="metal x-2 y-1"><span class="south">S</span><span class="west">W</span><span class="north">N</span></span>
|
|
<span class="metal x-3 y-1"><span class="south">S</span><span class="north">N</span></span>
|
|
<span class="metal x-0 y-2"><span class="east">E</span><span class="north">N</span></span>
|
|
<span class="metal x-1 y-2"><span class="east">E</span><span class="west">W</span><span class="north">N</span></span>
|
|
<span class="metal x-2 y-2"><span class="west">W</span><span class="north">N</span></span>
|
|
<span class="metal x-3 y-2"><span class="north">N</span></span>
|
|
<span class="metal x-0 y-3"><span class="east">E</span></span>
|
|
<span class="metal x-1 y-3"><span class="east">E</span><span class="west">W</span></span>
|
|
<span class="metal x-2 y-3"><span class="west">W</span></span>
|
|
<span class="metal x-3 y-3"></span>
|
|
</li>
|
|
</ul>
|
|
|
|
% id = "01HPMVT9BM65YD5AXWPT4Z67H5"
|
|
- (it's frustratingly hard to center individual letters like this in CSS. please forgive me for how crooked these are!)
|
|
|
|
% id = "01HPMVT9BM5V4BP8K80X0C1HJZ"
|
|
- note that the state of connection for a given cardinal direction can be represented using two values: **connected**, and **not connected**.
|
|
two values make one bit, so we can pack these four connection states into four bits, and use that as an array index!
|
|
|
|
% classes.branch = "tileset-cardinal-directions-demo"
|
|
id = "01HPMVT9BM4AXG2Z1D2QBH828G"
|
|
+ for that to work though, we need to rearrange our tilemap somewhat such that we can index into it easily using our integer.
|
|
assuming we pack our bits as `NWSE` (bit 0 is east, each next bit we go clockwise),
|
|
therefore the final arrangement is this:
|
|
|
|
<div class="horizontal-tile-strip">
|
|
<span class="metal x-3 y-3"></span>
|
|
<span class="metal x-0 y-3"><span class="east">E</span></span>
|
|
<span class="metal x-3 y-0"><span class="south">S</span></span>
|
|
<span class="metal x-0 y-0"><span class="east">E</span><span class="south">S</span></span>
|
|
<span class="metal x-2 y-3"><span class="west">W</span></span>
|
|
<span class="metal x-1 y-3"><span class="east">E</span><span class="west">W</span></span>
|
|
<span class="metal x-2 y-0"><span class="south">S</span><span class="west">W</span></span>
|
|
<span class="metal x-1 y-0"><span class="east">E</span><span class="south">S</span><span class="west">W</span></span>
|
|
<span class="metal x-3 y-2"><span class="north">N</span></span>
|
|
<span class="metal x-0 y-2"><span class="east">E</span><span class="north">N</span></span>
|
|
<span class="metal x-3 y-1"><span class="south">S</span><span class="north">N</span></span>
|
|
<span class="metal x-0 y-1"><span class="east">E</span><span class="south">S</span><span class="north">N</span></span>
|
|
<span class="metal x-2 y-2"><span class="west">W</span><span class="north">N</span></span>
|
|
<span class="metal x-1 y-2"><span class="east">E</span><span class="west">W</span><span class="north">N</span></span>
|
|
<span class="metal x-2 y-1"><span class="south">S</span><span class="west">W</span><span class="north">N</span></span>
|
|
<span class="metal x-1 y-1"><span class="east">E</span><span class="south">S</span><span class="west">W</span><span class="north">N</span></span>
|
|
</div>
|
|
|
|
packing that into a single tilesheet, or rather tile *strip*, we get this image:
|
|
|
|
![horizontal tile strip of 16 8x8 pixel metal tiles][pic:01HPMMR6DGKYTPZ9CK0WQWKNX5]
|
|
|
|
% id = "01HPMVT9BMMEM4HT4ANZ40992P"
|
|
- in JavaScript, drawing on a `<canvas>` using bitwise autotiling would look like this:
|
|
```javascript
|
|
for (let y = 0; y < tilemap.height; ++y) {
|
|
for (let x = 0; x < tilemap.width; ++x) {
|
|
// Assume `tilemap.at` is a function which returns the type of tile
|
|
// stored at coordinates (x, y).
|
|
let tile = tilemap.at(x, y);
|
|
|
|
// We need to treat *some* tile as an empty (fully transparent) tile.
|
|
// In our case that'll be 0.
|
|
if (tile != 0) {
|
|
let tileset = tilesets[tile];
|
|
|
|
// Now it's time to represent the tile connections as bits.
|
|
// For each cardinal direction we produce a different bit value, or 0 if there is
|
|
// no connection:
|
|
let connectedWithEast = shouldConnect(tile, tilemap.at(x + 1, y)) ? 0b0001 : 0;
|
|
let connectedWithSouth = shouldConnect(tile, tilemap.at(x, y + 1)) ? 0b0010 : 0;
|
|
let connectedWithWest = shouldConnect(tile, tilemap.at(x - 1, y)) ? 0b0100 : 0;
|
|
let connectedWithNorth = shouldConnect(tile, tilemap.at(x, y - 1)) ? 0b1000 : 0;
|
|
// Then we OR them together into one integer.
|
|
let tileIndex = connectedWithNorth
|
|
| connectedWithWest
|
|
| connectedWithSouth
|
|
| connectedWithEast;
|
|
|
|
// With that, we can draw the correct tile.
|
|
// Our strip is a single horizontal line, so we can assume
|
|
let tilesetTileSize = tileset.height;
|
|
let tilesetX = tileIndex * tilesetTileSize;
|
|
let tilesetY = 0;
|
|
ctx.drawImage(
|
|
tilesets[tile],
|
|
tilesetX, tilesetY, tilesetTileSize, tilesetTileSize,
|
|
x * tileSize, y * tileSize, tileSize, tileSize,
|
|
);
|
|
}
|
|
}
|
|
}
|
|
```
|
|
|
|
% template = true
|
|
id = "01HPMVT9BM9CS9375MX4H9WKW8"
|
|
- and that gives us this result:
|
|
|
|
<canvas
|
|
is="tairu-editor"
|
|
data-tilemap-id="bitwiseAutotiling"
|
|
data-tile-size="40"
|
|
>
|
|
Your browser does not support <canvas>.
|
|
<img class="resource" src="{% pic 01HPMMR6DGKYTPZ9CK0WQWKNX5 %}" data-tairu-tileset="1">
|
|
</canvas>
|
|
|
|
% id = "01HPMVT9BM3WR0BNZFHP2BPZ8A"
|
|
- but if you play around with it (or have *already* played around with it, and are therefore left with a non-default tilemap)
|
|
|
|
...something seems awful about it doesn't it?
|
|
|
|
% template = true
|
|
id = "01HPMVT9BMPA89037VPWPPWX8V"
|
|
- something's off about the corners. let me give you a fresh example to illustrate what I mean:
|
|
|
|
<canvas
|
|
is="tairu-editor"
|
|
data-tilemap-id="bitwiseAutotilingChapter2"
|
|
data-tile-size="40"
|
|
>
|
|
Your browser does not support <canvas>.
|
|
<img class="resource" src="{% pic 01HPMMR6DGKYTPZ9CK0WQWKNX5 %}" data-tairu-tileset="1">
|
|
</canvas>
|
|
|
|
% id = "01HPMVT9BM16EF3TV5J1K19JAM"
|
|
+ see that tile in the bottom left corner of the `L` shape? it's missing a corner.
|
|
the top-right corner, to be exact, which makes it visually disjoint from the tiles to the north and the east.
|
|
|
|
% id = "01HPMVT9BM5VWJSMDNPK2SRNZV"
|
|
- (I'm totally not trying to say this implementation is an L so far)
|
|
|
|
% id = "01HPMVT9BMWG6QHQ125Z884W8Z"
|
|
+ i'll cut right to the chase here and say it outright - the issue is that we simply don't have enough tiles to represent corner cases like this!
|
|
|
|
% id = "01HPMVT9BMQK8N1H68YV3J4CFQ"
|
|
- see what I did there?
|
|
|
|
% id = "01HPMVT9BMJTG3KD3K5EJ3BC93"
|
|
- the solution here is to introduce more tiles to handle these edge cases.
|
|
|
|
TODO Explain
|
|
|
|
% id = "01HPD4XQPWT9N8X9BD9GKWD78F"
|
|
- bitwise autotiling is a really cool technique that I've used in plenty of games in the past
|
|
|
|
% id = "01HPD4XQPW5FQY8M04S6JEBDHQ"
|
|
- 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
|
|
|
|
% id = "01HPJ8GHDEN4XRPT1AJ1BTNTFJ"
|
|
- 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
|
|
|
|
% id = "01HPD4XQPWPN6HNA6M6EH507C6"
|
|
+ but one day I found a really cool project called [Tilekit](https://rxi.itch.io/tilekit)
|
|
|
|
% id = "01HPD4XQPW11EQTBDQSGXW3S52"
|
|
+ (of course it's really cool, after all rxi made it)
|
|
|
|
% id = "01HPD4XQPWYHS327BV586SB085"
|
|
- for context rxi is the genius behind the Lua-powered, simple, and modular text editor `lite` that I was using for quite a while
|
|
|
|
% id = "01HPD4XQPWJ9QAQ5MF2J5JBB8M"
|
|
- after a while I switched to a fork - Lite XL, which had better font rendering and more features
|
|
|
|
% id = "01HPD4XQPWB11TZSX5VAAJ6TCD"
|
|
- I stopped using it because VS Code was just more feature packed and usable; no need to reinvent the wheel, rust-analyzer *just works.*
|
|
|
|
% id = "01HPD4XQPW3G7BXTBBTD05MB8V"
|
|
- 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.
|
|
|
|
% id = "01HPD4XQPWV1BAPA27SNDFR93B"
|
|
- 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
|
|
|
|
% id = "01HPD4XQPWM1JSAPXVT6NBHKYY"
|
|
classes.branch_children = "branch-quote"
|
|
- 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
|
|
|
|
% id = "01HPD4XQPWE7ZVR0SS67DHTGHQ"
|
|
- autotile using this base tileset
|
|
|
|
% id = "01HPD4XQPW2BFZYQQ920SYHM9M"
|
|
- if the tile above is empty AND with a 50% chance
|
|
|
|
% id = "01HPD4XQPWJB7V67TS1M3HFCYE"
|
|
- then grass
|
|
|
|
% id = "01HPD4XQPWF7K85Z0CEK4WDDBZ"
|
|
- if the tile above is solid AND with a 10% chance
|
|
|
|
% id = "01HPD4XQPW5J3N6MVT9Z2W00S9"
|
|
- then vines
|
|
|
|
% id = "01HPD4XQPWGCMCEAR5Z9EETSGP"
|
|
- if the tile above is vines AND with a 50% chance
|
|
|
|
% id = "01HPD4XQPWP847T0EAM0FJ88T4"
|
|
- then vines
|
|
|
|
% id = "01HPD4XQPWK58Z63X6962STADR"
|
|
- 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?
|
|
|
|
% id = "01HPJ8GHDFRA2SPNHKJYD0SYPP"
|
|
- of course Tilekit's solution is a lot more simple, streamlined, and user-friendly, but you get the gist.
|
|
|
|
% id = "01HPD4XQPW4Y075XWJCT6AATB2"
|
|
- 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
|
|
|
|
% id = "01HPD4XQPWR8J9WCNBNCTJERZS"
|
|
- and what you're reading is the result of that.
|
|
|
|
% id = "01HPD4XQPW1EP8YHACRJVMA0GM"
|
|
- so let's get going! first, we'll build a basic tile editor using JavaScript.
|
|
|
|
% id = "01HPD4XQPWPNRTVJFNFGNHJMG1"
|
|
+ not my favorite language, but we're on the Web so it's not like we have much more of a choice.
|
|
|
|
% id = "01HPD4XQPWGK7M4XJYC99XE4T6"
|
|
- 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.
|
|
|
|
% id = "01HPD4XQPWAE0ZH46WME6WJSVP"
|
|
- I'll be using Web Components (in particular, custom elements) combined with canvas to add stuff onto the page.
|