MapLoader: use square tile texture rather than long Nx1 rectangle

By placing the tiles in a square texture, the dimensions are bounded by the
square root of the dimension in the old solution. This way we can fit a
significantly higher number of tiles into it without using up all the
accuracy of the coordinates.

2 files changed, 50 insertions, 35 deletions

diff --git a/src/view/MapLoader.ts b/src/view/MapLoader.ts
index 290f095..6953321 100644
--- a/src/view/MapLoader.ts
+++ b/src/view/MapLoader.ts
@@ -4,6 +4,11 @@ import MapState from '../model/state/MapState';
 import MapView from './MapView';
 import Renderer from './renderer/Renderer';
 
+export interface TileMap {
+	texture: WebGLTexture;
+	tiles: Map<string, [number, number, number, number]>;
+}
+
 function loadImage(url: string): Promise<HTMLImageElement> {
 	return new Promise((resolve, reject) => {
 		const img = new Image();
@@ -36,27 +41,42 @@ function mkTexture(gl: WebGLRenderingContext, src: HTMLCanvasElement|HTMLImageEl
 	return texture;
 }
 
-function mkTileTexture(gl: WebGLRenderingContext, tiles: Map<string, HTMLImageElement>):
-[WebGLTexture, Map<string, number>] {
+function mkTileMap(
+	gl: WebGLRenderingContext,
+	tiles: Map<string, HTMLImageElement>,
+): TileMap {
+	const tileSize = MapView.tileSize;
+
+	const canvasDim = nextPowerOf2(Math.sqrt(tiles.size));
+	const canvasSize = canvasDim * tileSize;
+
 	const canvas = document.createElement('canvas');
-	canvas.width = nextPowerOf2(tiles.size) * MapView.tileSize;
-	canvas.height = MapView.tileSize;
+	canvas.width = canvas.height = canvasSize;
 
-	let i = 0;
-	const ret: Map<string, number> = new Map();
+	let x = 0, y = 0;
+	const map: Map<string, [number, number, number, number]> = new Map();
 	const ctx = canvas.getContext('2d') as CanvasRenderingContext2D;
 
 	for (const [k, tile] of tiles) {
-		ctx.drawImage(tile, i * MapView.tileSize, 0);
-		ret.set(k, i++);
+		ctx.drawImage(tile, x * tileSize, y * tileSize);
+		map.set(k, [x / canvasDim, y / canvasDim, (x + 1) / canvasDim, (y + 1) / canvasDim]);
+
+		x++;
+		if (x === canvasDim) {
+			x = 0;
+			y++;
+		}
 	}
 
-	return [mkTexture(gl, canvas), ret];
+	return {
+		texture: mkTexture(gl, canvas),
+		tiles: map,
+	};
 }
 
 export async function loadMap(r: Renderer, map: MapState): Promise<MapView> {
 	const tiles = await loadTiles(map.data.tiles);
-	const [tileTexture, tileMap] = mkTileTexture(r.getContext(), tiles);
+	const tileMap = mkTileMap(r.getContext(), tiles);
 
-	return new MapView(r, map, tileTexture, tileMap);
+	return new MapView(r, map, tileMap);
 }
diff --git a/src/view/MapView.ts b/src/view/MapView.ts
index 92784b7..5c30f20 100644
--- a/src/view/MapView.ts
+++ b/src/view/MapView.ts
@@ -1,6 +1,5 @@
-import {nextPowerOf2} from '../util';
-
 import MapState from '../model/state/MapState';
+import {TileMap} from './MapLoader';
 import Renderer from './renderer/Renderer';
 
 export default class MapView {
@@ -14,17 +13,14 @@ export default class MapView {
 	constructor(
 		private readonly r: Renderer,
 		private readonly map: MapState,
-		private readonly tileTexture: WebGLTexture,
-		private readonly tileMap: Map<string, number>,
+		private readonly tileMap: TileMap,
 	) {
 		const vertexData: number[] = [];
 		const textureData: number[] = [];
 
-		const tileCount = nextPowerOf2(tileMap.size);
-
 		for (let x = 0; x < map.data.width; x++)
 			for (let y = 0; y < map.data.height; y++)
-				this.addTile(vertexData, textureData, x, y, map.data.layers[0][y][x], tileCount);
+				this.addTile(vertexData, textureData, x, y, map.data.layers[0][y][x]);
 
 		const gl = r.getContext();
 
@@ -43,7 +39,7 @@ export default class MapView {
 		gl.clear(gl.COLOR_BUFFER_BIT);
 
 		gl.activeTexture(gl.TEXTURE0);
-		gl.bindTexture(gl.TEXTURE_2D, this.tileTexture);
+		gl.bindTexture(gl.TEXTURE_2D, this.tileMap.texture);
 		gl.uniform1i(this.r.getSamplerLoc(), 0);
 
 		gl.bindBuffer(gl.ARRAY_BUFFER, this.vertexBuffer);
@@ -55,25 +51,24 @@ export default class MapView {
 		gl.drawArrays(gl.TRIANGLES, 0, 6 * this.map.data.width * this.map.data.height);
 	}
 
-	private addTile(vertexData: number[], textureData: number[], x: number, y: number, tile: string, tileCount: number) {
-		const tileID = this.tileMap.get(tile);
-		if (tileID === undefined)
-			throw new Error('invalid tile specifier in map data');
+	private pushTile(buf: number[], coords: [number, number, number, number]) {
+		const [x1, y1, x2, y2] = coords;
 
-		vertexData.push(x); vertexData.push(y);
-		vertexData.push(x + 1); vertexData.push(y);
-		vertexData.push(x); vertexData.push(y + 1);
+		buf.push(x1); buf.push(y1);
+		buf.push(x2); buf.push(y1);
+		buf.push(x1); buf.push(y2);
 
-		vertexData.push(x); vertexData.push(y + 1);
-		vertexData.push(x + 1); vertexData.push(y);
-		vertexData.push(x + 1); vertexData.push(y + 1);
+		buf.push(x1); buf.push(y2);
+		buf.push(x2); buf.push(y1);
+		buf.push(x2); buf.push(y2);
+	}
 
-		textureData.push(tileID / tileCount); textureData.push(0);
-		textureData.push((tileID + 1) / tileCount); textureData.push(0);
-		textureData.push(tileID / tileCount); textureData.push(1);
+	private addTile(vertexData: number[], textureData: number[], x: number, y: number, tile: string) {
+		const tilePos = this.tileMap.tiles.get(tile);
+		if (!tilePos)
+			throw new Error('invalid tile specifier in map data');
 
-		textureData.push(tileID / tileCount); textureData.push(1);
-		textureData.push((tileID + 1) / tileCount); textureData.push(0);
-		textureData.push((tileID + 1) / tileCount); textureData.push(1);
+		this.pushTile(vertexData, [x, y, x + 1, y + 1]);
+		this.pushTile(textureData, tilePos);
 	}
 }