Some slight refactoring

util.ts

@@ -44,4 +44,38 @@ export const drawTransparentRect = (x: number, y: number, w: number, h: number)
 		const jy = Math.floor(j/w);
 		setPixelColor(x+jx, y+jy, (jx+jy)%2 ? COLOR.BLACK : COLOR.DARKGRAY);
 	})
-}
+}
+
+export const subgrid = <T>(array: Array<T>, gridW: number, x: number, y: number, w: number, h: number): Array<T> => {
+	return Array(h).fill(0).flatMap((_, i) => {
+		const start = (y+i)*gridW+x;
+		return array.slice(start, start+w);
+	})
+}
+
+export const LinearGrid = <T>(array: Array<T>, gridW: number) => {
+	return {
+		get(x: number, y: number) {
+			return array[this.coordsToIndex(x, y)]
+		},
+		getIndex(i: number) {
+			return array[i];
+		},
+		set(x: number, y: number, value: T) {
+			array[this.coordsToIndex(x, y)] = value;
+		},
+		setIndex(i: number, value: T) {
+			array[i] = value;
+		},
+		values: array,
+		indexToCoords: (i: number) => {
+			return [i%gridW, Math.floor(i/gridW)];
+		},
+		coordsToIndex: (x: number, y: number) => {
+			return y*gridW+x;
+		},
+		// TODO: make alterations to subgrid affect parent grid
+		subgrid: (x: number, y: number, w: number, h: number) => LinearGrid(subgrid(array, gridW, x, y, w, h), w),
+	}
+}
+