add world utility function for setting tiles to empty.

previously, world generation would represent empty tiles as the number
0, while other code would expect them to be an object with its `type`
property set to `"empty"`. the object representation is now used
consistently.

js/graphics.mjs

@@ -37,8 +37,7 @@ export function draw_world (box, start_x = 0, start_y = 0, scale = BASE_SCALE) {
 
 	draw_floor(start_x, start_y, scale, !checkerboard(start_x, start_y));
 
-	iter_2d(range(0, world.BOX_SIZE - 1), (x, y) => {
-		const tile = world.get_tile(box, x, y);
+	world.for_each_tile(box, (x, y, tile) => {
 		draw_tile(tile, x * scale + start_x, y * scale + start_y, scale);
 	});
 

js/main.mjs

@@ -1,5 +1,5 @@
 import * as graphics from "./graphics.mjs";
-import { BOX_SIZE, get_tile } from "./world.mjs";
+import { BOX_SIZE, get_tile, get_root } from "./world.mjs";
 import { get_player_box } from "./player.mjs";
 import { save_in_browser, load_from_browser } from "./save_load.mjs";
 import { tick } from "/js/tile_update.mjs";
@@ -21,7 +21,7 @@ function main (timestamp) {
 	const delta = dt_ms / 1000;
 
 	render(delta);
-	tick(delta);
+	tick(get_root(), delta);
 
 	requestAnimationFrame(main);
 }

js/player.mjs

@@ -33,9 +33,7 @@ on_press(" ", _ => {
 });
 
 function clear_tile (x, y) {
-	world.set_tile(player.box, x, y, {
-		type: "empty",
-	});
+	world.clear_tile(player.box, x, y);
 }
 
 on_press("Backspace", _ => {

js/tile_update.mjs

@@ -6,8 +6,7 @@ import * as random from "/js/utils/random.mjs";
 
 // lots of this code is very hacky temporary for testing things out & getting started with tile updates.
 
-export function tick (delta_time) {
-	const box = get_player_box();
+export function tick (box, delta_time) {
 	world.for_each_tile(box, (x, y, tile) => {
 		if (tile_tickers.has(tile.type)) {
 			tile_tickers.get(tile.type)(box, x, y, delta_time);
@@ -24,15 +23,25 @@ const dirs = [
 	[ 0, 1 ],
 ];
 
+// this might become terrible for performance eventually.
+tile_tickers.set("box", (box, x, y, delta_time) => {
+	tick(world.get_tile(box, x, y).box, delta_time);
+});
+
 tile_tickers.set("grass", (box, x, y, delta_time) => {
 	const tile = world.get_tile(box, x, y);
-	if (Math.random() > 0.9 ** delta_time) {
+	if (Math.random() > 0.8 ** delta_time) {
 		const dir = random.item(dirs);
-		const [ d_x, d_y ] = dir;
-		if (world.get_tile(box, x + d_x, y + d_y).type === "empty") {
-			world.set_tile(box, x + d_x, y + d_y, {
-				type: "grass",
-			});
+		const spaces = random.shuffle(dirs)
+			.map(([d_x, d_y]) => [x + d_x, y + d_y]);
+
+		for (const [new_x, new_y] of spaces) {
+			if (world.get_tile(box, new_x, new_y).type === "empty") {
+				world.set_tile(box, new_x, new_y, {
+					type: "grass",
+				});
+				break;
+			}
 		}
 	};
 });

js/utils/random.mjs

@@ -9,3 +9,13 @@ export function integer (min, max) {
 export function item (array) {
 	return array[integer(0, array.length)];
 }
+
+export function shuffle (array) {
+	const copy = [ ...array ];
+	const result = [];
+	while (copy.length > 0) {
+		const index = integer(0, copy.length);
+		result.push(copy.splice(index, 1)[0]);
+	}
+	return result;
+}

js/world.mjs

@@ -7,12 +7,18 @@ export const CENTER = Math.floor(BOX_SIZE / 2);
 
 function create_world (size) {
 	return {
-		tiles: Array(size).fill(0).map(_ => Array(size).fill(0)),
+		tiles: Array(size).fill(0).map(_ =>
+			Array(size).fill(0).map(_ => empty_tile())
+		),
 		depth: 0,
 	};
 }
 const world = create_world(BOX_SIZE);
 
+export function empty_tile () {
+	return { type: "empty" };
+}
+
 export function create_new () {
 	return create_world(BOX_SIZE);
 }
@@ -27,6 +33,10 @@ export function get_tile (world, x, y) {
 	return world.tiles[x][y];
 }
 
+export function clear_tile (box, x, y) {
+	set_tile(box, x, y, empty_tile());
+}
+
 export function create_box (parent) {
 	return {
 		...create_world(BOX_SIZE),
@@ -73,7 +83,10 @@ function reconstruct_parent (world, parent) {
 }
 
 export function from_json (json) {
-	const result = JSON.parse(json);
+	const result = JSON.parse(json, (key, value) => {
+		if (value === undefined || value === 0 || value === null) return empty_tile();
+		return value;
+	});
 
 	for_each_tile(result, (x, y, tile) => {
 		if (tile.type === "box") {