function addRectangles(rectangles) {
let grid = createGrid();
for (let i = 0; i < rectangles.length; i++) {
let rectangle = rectangles[i];
for (let j = 0; j < rectangle.width / 30; j++) {
for (let k = 0; k < rectangle.height / 30; k++) {
let x = rectangle.x / 30 + j;
let y = rectangle.y / 30 + k;
if (grid[y] !== undefined && grid[y][x] !== undefined) {
grid[y][x] = true;
}
}
}
}
return grid;
}