Maze generator & solver · step-5-preview

Let me build this maze generator/solver visualization. I's write a single self-contained index.html with canvas, recursive backtracking, BFS, animation, controls, and legend.

Let me write it carefully.

Key features:
- 25x15 maze, recursive backtracking with animation
- canvas drawing, walls
- Start upper-left, Finish lower-right
- BFS explore animation, then path highlight
- New Maze, Replay Solver buttons
- Legend
- Handle cancellation with requestAnimationFrame loop using a generation token/series id.

Let me code it.

Implementation detail: maze grid of cells, each cell has walls top/right/bottom/left. Recursive backtracking: visit in order, animate each carve step.

Animation: use a loop driven by rAF, stepping N steps per frame. Use a "runId" token; when New Maze clicked, increment runId and abort previous.

BFS: from start to finish, record visited order for animation, then path reconstruct.

Draw: cell size computed from canvas size.

Let me write the code.

Canvas size: responsive — let's fix to, say, width 900, height 540 with cell size 36? 25 cols * 36 = 900, 15 rows * 36 = 540. Good. But maybe make responsive to container. Keep fixed internal resolution with CSS scaling to 100% max-width.

Also add speeds? Not required but nice. Keep simple.

Let me write.

For animation speed of generation: maybe 3 steps per frame — total steps 375 cells => ~125 frames ≈ 2s. Solver: BFS visited steps maybe 1-2 per frame.

Write code:

state:
```
let maze = {w,h, cells} // cells[y][x] = {walls: [top,right,bottom,left], visited}
```
Carving recursive backtracking iteratively with stack.

Generation loop: uses stack; each "step": pop a cell, if unvisited, mark visited, pick random unvisited neighbor, push current and neighbor, carve wall between. Actually standard implementation.

Let me implement generation state:
```
let gen = { stack: [], current: null, phase: 'idle' }
```

Simpler: do like this:

```
function initMaze(){ walls all true; visited all false }
startGen:
  stack = [{x:0,y:0}]; visited[0][0]=true;
  loop step:
    if stack empty -> done
    cur = top
    neighbors = unvisited neighbors of cur
    if neighbors.length: choose random n, carve between cur and n, push n, mark visited
    else stack.pop()
```

Animate these steps.

Then solver BFS:
```
bfs(): queue, prev map. record order of dequeued (or enqueued) cells as explored sequence.
```

Animation: draw progressively: explored cells colored, current cell highlighted. Then path animation: draw path cells one by one, then full path line.

Draw function: draws walls always (thin lines), plus cell fill for explored/path.

Colors: start green, finish red-ish, explored light blue, path yellow/orange, current cell brighter.

Legend in HTML below canvas.

Handle resize? Fixed canvas is fine; use CSS max-width.

Let me also handle "Replay Solver" disabled until maze generated. Keep it simple: if generation not complete, replay just re-runs solver if maze exists.

Edge case: clicking New Maze while generation in progress: increment runId; new init; the old rAF loop checks runId mismatch and stops. Actually simplest: cancel pending rAF and set a flag; new loop starts.

Let me use a single `animId` and `epoch`. I'll write:

```
let rafId = null;
let epoch = 0;
function cancel(){ if(rafId) cancelAnimationFrame(rafId); rafId=null; epoch++; }
function stepLoop(fn) — uses captured epoch...
```

Implementation:

```
function startGen(){
  cancel();
  const e = epoch;
  ... init ...
  rafId = requestAnimationFrame(function tick(ts){ if(e!==epoch) return; doGenSteps(...); draw(); if(genDone) { onGenDone(e) } else rafId = requestAnimationFrame(tick); });
}
```

Careful with rAF timestamp param passing.

Let me write full file now.

Also need "verify" pass with browser: load, check console, screenshot mid-generation, click New Maze during animation, screenshot, check solver steps. I'll do a quick pass.

Write the file.

There's a typo in CSS: `background: #2b3murky;` — harmless but let me fix it (invalid value, then overridden). Fix it.

Then test in browser.

Initial view fine. Now click New Maze and quickly screenshot mid-carving. Let me click New Maze then screenshot immediately.

I'll click New Maze at coordinates (68, 116 roughly based on 1200x800 viewport scaled). The canvas is 940 max width; the button position... Let's just use the click with coordinates from the screenshot: page is 1200 wide, wrap max 940 centered => left margin 130. Buttons: New Maze at ~x=145, y=116. Let's click at (145, 116).

The click apparently didn't hit the button — status still "Click "New Maze" to begin". Maybe coordinates off, or click hit the button but... it should update status immediately. Possibly the button is at different y. Let me find the button coordinates. The screenshot is 1200x800. Header text at top ~y=45. Controls row below. Buttons at y ≈ 105-125? The click at y=116 should hit. Hmm, maybe the click coordinate mapping differs (page is scrolled?). Let me try clicking using a different approach — maybe the harness click on button element? We only have coordinates. Let me use inspect to see DOM elementRects.

The DOM text output lists buttons as text but no element info. I can't get bounding rects. Let me instead verify functionality via a JS-driven test using... I can't run arbitrary JS directly. Hmm. But I can use "type"? No.

Alternative: click with different coordinates. Perhaps the click did land but animation was so fast? No — carving takes ~2s and status would show "Carving maze...". The status still shows initial.

Maybe clicks need to be dispatched but the harness requires exact element? Let me try clicking a slightly different position, e.g., (145, 100) or use keyboard? Let me try (160, 108).

Carving progress visible. Now click New Maze again during animation to test cancellation, then wait and screenshot to check final solved state.

New maze generation restarted cleanly (fresh carving, previous view replaced). Now wait for generation + solve to complete and screenshot to verify solved path. Let me take a screenshot now — but generation takes ~2s; the screenshot is taken immediately after click. Let me click "Replay Solver"? No, better: just take a screenshot again after a delay. There's no "wait" action. I can do a no-op action like inspect to allow time to pass? Each tool call round-trip takes some time (~1s?). Let's try a screenshot now.

The solver explored (blue) and the path (yellow) is being highlighted from start and appears to reach... it's still drawing. Let me take another screenshot to see the complete path from START to END.

Path complete, contiguous from START to END, only through open passages. Now test Replay Solver: click it, then screenshot to see exploration restart. Note the path length is 127 which is long — but with BFS, that's the shortest path in this maze; fine.

Wait — a subtlety: the BFS exploration overlay marks visited in BFS order and frontier... fine.

Test Replay Solver.

The click on Replay Solver at x=245 didn't register (status unchanged). Maybe the button is at different x. New Maze button is ~ (160,108) hit; button width maybe ~90px, so Replay Solver starts around x=255? Let me estimate: wrap left edge... New Maze button spans roughly x 143-233 (width ~90 + padding 28 = ~118?). "New Maze" text width ~66px + padding 28 = 94. So Replay Solver ~ 143+94+10 = 247 to ~247+118=365. Click at 245 might be on gap/left edge. Try (300, 108).

Replay Solver works: uses the same maze (walls unchanged) and restarts BFS exploration from the start. Overlay cleared, exploration begins from start cell, spreading only along open passages (visible frontier light blue cell).

Also test: click New Maze during solver animation to confirm it cancels and restarts. Let's click New Maze (160,108) now during exploration.

New Maze during solver animation cleanly replaces the view: overlay cleared, fresh carving begins. Let me wait for it to finish solving once more to confirm the full pipeline completes and path reaches END (previous full run already confirmed). One more screenshot to confirm final state, then done.

Everything works. One more screenshot to confirm the path completes for this maze (should be shortly).