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maze-generator.html
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maze-generator.html
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<html>
<head><title>Maze generator</title>
<style>
section {
display: grid;
grid-template-columns: repeat(41, 12px);
grid-template-rows: repeat(41, 12px);
cursor: pointer;
}
div {
width: 10px;
height: 10px;
background: lightgrey;
}
div.black { background: black; }
</style>
</head>
<body>
<span id="msg">Random Maze</span>
<section>
<!-- 41x41 empty div elements will be added here. -->
</section>
<p>Click and drag to draw.</p>
<button id="clear">Clear to all white</button>
<button id="fill">Fill with all black</button>
<button id="make_maze_recur">Make maze (recursive)</button>
<button id="make_maze_iter">Make maze (iterative)</button>
<script>
const boardSize = 41;
const mazeSize = 20;
// Create the HTML elmements
let sectionEl = document.querySelector("section");
for (let r=0; r<boardSize; r++)
for (let c=0; c<boardSize; c++) {
let newDiv = document.createElement('div');
newDiv.dataset.r = r;
newDiv.dataset.c = c; sectionEl.appendChild(newDiv);
}
let pixels = document.querySelectorAll('section div');
let running = false;
// Board is matrix of pixels that start with desired color
let board = [];
function initializeBoard(color) {
board = [];
for (let r=0; r<boardSize; r++) {
let row = [];
board.push(row);
for (let c=0; c<boardSize; c++) {
row.push(color);
}
}
}
function render() {
let i = 0;
for (pixel of pixels) {
let r = Math.floor(i / boardSize);
let c = i % boardSize
pixel.className = board[r][c];
i++;
}
}
function fillBoard(color) {
initializeBoard(color);
render();
}
fillBoard('white');
const NORTH = {dx: 0, dy: -2};
const SOUTH = {dx: 0, dy: 2};
const EAST = {dx: -2, dy: 0};
const WEST = {dx: 2, dy: 0};
function findAllNeighbors(cellXY) {
let result = [];
for (let direction of [NORTH, SOUTH, EAST, WEST]) {
let neighborX = cellXY.x + direction.dx;
let neighborY = cellXY.y + direction.dy;
result.push({x: neighborX, y: neighborY});
}
return result;
}
function pickRandomItem(list) {
let index = Math.floor(Math.random() * list.length);
// Cut out a sublist starting at index with length 1.
let itemInAList = list.splice(index, 1);
return itemInAList[0]; // just return the single item
}
function visitRecursive(cellXY) {
// The maze cell that we are visiting is now part of the maze.
board[cellXY.x][cellXY.y] = 'white';
let neighborCells = findAllNeighbors(cellXY);
while (neighborCells.length) {
let potentialNeighbor = pickRandomItem(neighborCells);
// If the potential neighbor is in the bounds of the board and not already part of the maze, choose it.
if (board[potentialNeighbor.x] &&
board[potentialNeighbor.x][potentialNeighbor.y] == 'black') {
// Remove the wall between this cell and the next cell.
board[(cellXY.x + potentialNeighbor.x) / 2][(cellXY.y + potentialNeighbor.y) / 2] = 'white';
// Make that next cell part of the maze and keep going
visitRecursive(potentialNeighbor);
}
}
render();
}
function makeMazeRecursive() {
initializeBoard('black');
visitRecursive({x: 1, y: 1});
console.log('done');
render();
}
// These are cellXY values that are in the unexplored area, but adjacent to the explored area
let frontier = [];
function visitIterative(cellXY) {
// Add this cell to the maze.
if (board[cellXY.x][cellXY.y] == 'black') {
board[cellXY.x][cellXY.y] = 'white';
// Connect it to the part of the existing maze that spawned it.
if (cellXY.connectionX) {
board[cellXY.connectionX][cellXY.connectionY] = 'white';
}
}
// Any unexplored adjacent cells are now added to the list of frontiers.
for (let direction of [NORTH, SOUTH, EAST, WEST]) {
let neighborX = cellXY.x + direction.dx;
let neighborY = cellXY.y + direction.dy;
if (board[neighborX] && board[neighborX][neighborY] == 'black') {
frontier.push({
x: neighborX,
y: neighborY,
connectionX: (cellXY.x + neighborX) / 2,
connectionY: (cellXY.y + neighborY) / 2,
});
// Prevent us from adding the same cell to the frontier again.
board[neighborX][neighborY] == 'frontier';
}
}
}
function makeMazeIterative() {
initializeBoard('black');
visitIterative({x: 1, y: 1});
while (frontier.length) {
let frontierCell = pickRandomItem(frontier);
visitIterative(frontierCell);
}
console.log('done');
render();
}
document.querySelector('#clear').addEventListener('click', (e) => fillBoard('white'));
document.querySelector('#fill').addEventListener('click', (e) => fillBoard('black'));
document.querySelector('#make_maze_recur').addEventListener('click', makeMazeRecursive);
document.querySelector('#make_maze_iter').addEventListener('click', makeMazeIterative);
//document.querySelector('#play-pause').addEventListener('click', playPause);
function gameLoop() {
//if (!running) return;
//update();
render();
}
window.setInterval(gameLoop, 100);
let drawingMode = 'black';
function draw(pixel) {
let r = Number(pixel.dataset.r);
let c = Number(pixel.dataset.c);
board[r][c] = drawingMode;
render();
}
function startDrawing(pixel) {
drawingMode = (pixel.className == 'black') ? 'white' : 'black';
draw(pixel);
}
pixels.forEach((pixel => {
pixel.addEventListener(
'mousedown', (e) => {
startDrawing(e.target);
});
pixel.addEventListener(
'mouseenter', (e) => {
if (e.buttons) draw(e.target);
});
}));
</script>
</body>
</html>