Proper bridge mask

ts/mask.ts

@@ -0,0 +1,42 @@
+export class Mask {
+  mask: boolean[][] = [];
+
+  constructor(width: number, height: number) {
+    for (let x = 0; x < width; x++) {
+      this.mask.push(Array(height).fill(false));
+    }
+  }
+
+  static from_string(mask_string: string): Mask {
+    // mask_string: '\n+++\n+++\n'
+    const rows = mask_string.trim().split('\n');
+    // rows: ['+++', '+++']
+
+    const mask = new Mask(rows[0].length, rows.length);
+
+    for (let y = 0; y < rows.length; y++) {
+      const row = rows[y];
+      for (let x = 0; x < row.length; x++) {
+        const cell = row[x].toLowerCase();
+        if (cell == '+' || cell == 'x') {
+          mask.set(x, y, true);
+        }
+      }
+    }
+
+    return mask;
+  }
+
+  set(x: number, y: number, val: boolean) {
+    this.mask[x][y] = val;
+  }
+
+  update(x: number, y: number, src: Mask) {
+    for (let xi = 0; xi < src.mask.length; xi++) {
+      const col = src.mask[xi];
+      for (let yi = 0; yi < col.length; yi++) {
+        this.set(x + xi, y + yi, col[yi]);
+      }
+    }
+  }
+}