Pixel Build Progress

Installation#

CLI

npx shadcn@latest add https://hantui-theta.vercel.app/r/pixel-build-progress.json

Manual

1. Install the dependencies

   npmpnpmbunyarn

   npm install clsx tailwind-merge

2. Add the shared helpers

   Components use cn() from lib/utils.ts and the motion tokens below. See Installation if you have not set them up yet.

   lib/glyph/canvas-loop.ts

   /**
    * The render loop every glyph and dither canvas shares: sizes the canvas to its host at a capped
    * pixel ratio, runs only while the host is on screen, the tab is visible, nothing is paused and
    * the user hasn't asked for reduced motion, and otherwise keeps one up-to-date still frame.
    * Framework-free: start it in an effect and dispose it in the cleanup. Browser only.
    */
   
   export interface CanvasLoopFrame {
     /** Seconds since the previous frame (capped at 0.05), or 0 for a redraw without advancing. */
     dt: number;
     /** Seconds the loop has been running. */
     time: number;
     /** True under reduced motion: draw a calm, finished-looking frame. */
     still: boolean;
     /** Host size in CSS pixels. */
     width: number;
     height: number;
     /** Device pixel ratio of the canvas (capped). */
     dpr: number;
   }
   
   export interface CanvasLoopOptions {
     /** Element observed for size and visibility. */
     host: HTMLElement;
     /** Canvas sized to the host times the pixel ratio. */
     canvas: HTMLCanvasElement;
     /** Advance by `frame.dt` and draw. Called every animation frame while running, and with dt 0 after resizes and redraws. */
     render: (frame: CanvasLoopFrame) => void;
     /** Called after the canvas is resized, before it is redrawn. */
     resize?: (frame: CanvasLoopFrame) => void;
     /** Read before every frame; while it returns true the loop stops and the last frame stays. */
     isPaused?: () => boolean;
     /** Highest device pixel ratio used. @default 2 */
     maxDpr?: number;
     /** Margin around the viewport that still counts as on screen. @default "120px" */
     rootMargin?: string;
   }
   
   export interface CanvasLoop {
     /** Re-checks paused, visibility and reduced motion, and starts or stops the loop. Call it when props change. */
     wake(): void;
     /** Draws one frame without advancing (no-op while the loop is running, since the next frame will). */
     redraw(): void;
     /** Stops the loop and removes every observer and listener. */
     dispose(): void;
   }
   
   export function runCanvasLoop(options: CanvasLoopOptions): CanvasLoop {
     const { host, canvas, rootMargin = "120px" } = options;
     const reducedMotion = window.matchMedia("(prefers-reduced-motion: reduce)");
     let width = 0;
     let height = 0;
     let dpr = 1;
     let raf = 0;
     let last = 0;
     let time = 0;
     let inView = false;
     let disposed = false;
   
     const frame = (dt: number): CanvasLoopFrame => ({ dt, time, still: reducedMotion.matches, width, height, dpr });
     const shouldRun = () => !disposed && inView && !document.hidden && !reducedMotion.matches && !options.isPaused?.();
   
     const tick = (now: number) => {
       raf = 0;
       if (!shouldRun()) return;
       const dt = last ? Math.min(0.05, (now - last) / 1000) : 0;
       last = now;
       time += dt;
       options.render(frame(dt));
       raf = requestAnimationFrame(tick);
     };
   
     const wake = () => {
       if (disposed) return;
       if (shouldRun()) {
         if (!raf) {
           last = 0;
           raf = requestAnimationFrame(tick);
         }
         return;
       }
       if (raf) cancelAnimationFrame(raf);
       raf = 0;
     };
   
     const redraw = () => {
       if (!disposed && !raf && width > 0) options.render(frame(0));
     };
   
     const resize = () => {
       width = Math.max(1, host.clientWidth);
       height = Math.max(1, host.clientHeight);
       dpr = Math.min(window.devicePixelRatio || 1, options.maxDpr ?? 2);
       const w = Math.max(1, Math.round(width * dpr));
       const h = Math.max(1, Math.round(height * dpr));
       if (canvas.width !== w || canvas.height !== h) {
         canvas.width = w;
         canvas.height = h;
       }
       options.resize?.(frame(0));
       // Resizing clears the canvas, so repaint right away even while running.
       options.render(frame(0));
     };
   
     const resizeObserver = new ResizeObserver(resize);
     const intersection = new IntersectionObserver(
       ([entry]) => {
         inView = entry?.isIntersecting ?? true;
         wake();
       },
       { rootMargin },
     );
     const onVisibility = () => wake();
     const onMotionChange = () => {
       wake();
       redraw();
     };
   
     resize();
     resizeObserver.observe(host);
     intersection.observe(host);
     document.addEventListener("visibilitychange", onVisibility);
     reducedMotion.addEventListener("change", onMotionChange);
   
     return {
       wake,
       redraw,
       dispose() {
         disposed = true;
         if (raf) cancelAnimationFrame(raf);
         raf = 0;
         resizeObserver.disconnect();
         intersection.disconnect();
         document.removeEventListener("visibilitychange", onVisibility);
         reducedMotion.removeEventListener("change", onMotionChange);
       },
     };
   }

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   lib/pixel-art/sprites.ts

   /**
    * Palette-indexed sprite sheets for canvas pixel art, and a low-res buffer that is drawn at a
    * logical pixel size and blitted at a whole-number scale, so pixels stay square and crisp.
    * Framework-free. The canvas helpers are browser only: call them from effects.
    */
   
   export interface SpriteSheet {
     /** Frame width in logical pixels. */
     w: number;
     /** Frame height in logical pixels. */
     h: number;
     /** One palette index per pixel, row by row. Index 0 is transparent. */
     frames: Uint8Array[];
     /** CSS colors by index. Entry 0 is unused (transparent). */
     palette: readonly string[];
   }
   
   /**
    * Builds a sheet from character maps, the same authoring format as the pixel icons: one string
    * per row, one character per pixel, `.` for transparent. `colors` maps each character to a CSS
    * color, and its key order becomes the palette order (starting at index 1).
    */
   export function spriteSheet(frames: readonly (readonly string[])[], colors: Readonly<Record<string, string>>): SpriteSheet {
     const keys = Object.keys(colors);
     const h = frames[0]?.length ?? 0;
     const w = frames[0]?.[0]?.length ?? 0;
     return {
       w,
       h,
       palette: ["transparent", ...keys.map((key) => colors[key])],
       frames: frames.map((rows) => {
         const data = new Uint8Array(w * h);
         for (let y = 0; y < h; y++) {
           const row = rows[y] ?? "";
           for (let x = 0; x < w; x++) data[y * w + x] = keys.indexOf(row[x] ?? ".") + 1;
         }
         return data;
       }),
     };
   }
   
   export interface DrawSpriteOptions {
     /** Mirror the frame horizontally. */
     flip?: boolean;
     /** Palette to use instead of the sheet's, e.g. a recolored vest. Same indices. */
     palette?: readonly string[];
   }
   
   /**
    * Draws one frame at a whole-pixel position (x and y are rounded, so sprites never land between
    * pixels). Horizontal runs of one color are filled as a single rect.
    */
   export function drawSprite(ctx: CanvasRenderingContext2D, sheet: SpriteSheet, frame: number, x: number, y: number, options: DrawSpriteOptions = {}) {
     const data = sheet.frames[((frame % sheet.frames.length) + sheet.frames.length) % sheet.frames.length];
     if (!data) return;
     const palette = options.palette ?? sheet.palette;
     const { w, h } = sheet;
     const ox = Math.round(x);
     const oy = Math.round(y);
     let fill = "";
     for (let row = 0; row < h; row++) {
       let col = 0;
       while (col < w) {
         const index = data[row * w + (options.flip ? w - 1 - col : col)];
         if (!index) {
           col++;
           continue;
         }
         let run = 1;
         while (col + run < w && data[row * w + (options.flip ? w - 1 - col - run : col + run)] === index) run++;
         const color = palette[index] ?? sheet.palette[index];
         if (color !== fill) {
           fill = color;
           ctx.fillStyle = color;
         }
         ctx.fillRect(ox + col, oy + row, run, 1);
         col += run;
       }
     }
   }
   
   export interface PixelBuffer {
     /** Offscreen canvas at the logical size. Draw sprites here. */
     canvas: HTMLCanvasElement;
     ctx: CanvasRenderingContext2D;
     width: number;
     height: number;
   }
   
   /** An offscreen canvas at a logical pixel size. Returns null when 2D canvas is unavailable. */
   export function createPixelBuffer(width: number, height: number): PixelBuffer | null {
     const canvas = document.createElement("canvas");
     canvas.width = width;
     canvas.height = height;
     const ctx = canvas.getContext("2d");
     if (!ctx) return null;
     ctx.imageSmoothingEnabled = false;
     return { canvas, ctx, width, height };
   }
   
   /** The largest whole-number scale at which a logical size fits the target (at least 1). */
   export function integerScale(logicalWidth: number, logicalHeight: number, targetWidth: number, targetHeight: number, max = Infinity) {
     return Math.max(1, Math.min(max, Math.floor(Math.min(targetWidth / logicalWidth, targetHeight / logicalHeight))));
   }
   
   export interface BlitOptions {
     /** Scale to use instead of the largest that fits. Rounded to a whole number. */
     scale?: number;
     /** Horizontal anchor inside the target, 0 (left) to 1 (right). @default 0.5 */
     alignX?: number;
     /** Vertical anchor inside the target, 0 (top) to 1 (bottom). @default 0.5 */
     alignY?: number;
   }
   
   /**
    * Draws a pixel buffer onto a canvas context at a whole-number scale with smoothing off.
    * `targetWidth` and `targetHeight` are in the context's own pixels (device pixels for a canvas
    * sized by the shared canvas loop). Returns the scale and offset used, for pointer mapping.
    */
   export function blitPixelBuffer(ctx: CanvasRenderingContext2D, buffer: PixelBuffer, targetWidth: number, targetHeight: number, options: BlitOptions = {}) {
     const scale = Math.max(1, Math.round(options.scale ?? integerScale(buffer.width, buffer.height, targetWidth, targetHeight)));
     const width = buffer.width * scale;
     const height = buffer.height * scale;
     const x = Math.round((targetWidth - width) * (options.alignX ?? 0.5));
     const y = Math.round((targetHeight - height) * (options.alignY ?? 0.5));
     ctx.imageSmoothingEnabled = false;
     ctx.drawImage(buffer.canvas, 0, 0, buffer.width, buffer.height, x, y, width, height);
     return { scale, x, y, width, height };
   }
   
   /**
    * Sizes a visible canvas to a logical pixel size and scales it with CSS by a whole number, for
    * scenes that draw straight to the canvas without a separate buffer. Returns the scale.
    */
   export function fitPixelCanvas(canvas: HTMLCanvasElement, logicalWidth: number, logicalHeight: number, scale: number) {
     const whole = Math.max(1, Math.round(scale));
     if (canvas.width !== logicalWidth) canvas.width = logicalWidth;
     if (canvas.height !== logicalHeight) canvas.height = logicalHeight;
     canvas.style.width = `${logicalWidth * whole}px`;
     canvas.style.height = `${logicalHeight * whole}px`;
     canvas.style.imageRendering = "pixelated";
     const ctx = canvas.getContext("2d");
     if (ctx) ctx.imageSmoothingEnabled = false;
     return whole;
   }

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3. Copy the source

   components/ui/pixel-build-progress/pixel-build-progress.tsx

   "use client";
   
   import { useEffect, useRef, useState, type ComponentProps } from "react";
   import { cn } from "@/lib/utils";
   import { runCanvasLoop } from "@/lib/glyph/canvas-loop";
   import { createPixelBuffer, drawSprite, spriteSheet, type SpriteSheet } from "@/lib/pixel-art/sprites";
   
   export interface PixelBuildMessage {
     /** The caption shows while progress is below this value (in the same units as `max`). */
     until: number;
     /** Caption text. */
     text: string;
   }
   
   export interface PixelBuildPalette {
     /** Sky, top to bottom. */
     sky?: [string, string, string];
     /** The two brick tones. */
     brick?: [string, string];
     /** Mortar between bricks. */
     mortar?: string;
     /** Ground strip. */
     ground?: string;
     /** Workers' vests. */
     vest?: string;
     /** Workers' hard hats and the crane. */
     helmet?: string;
   }
   
   export interface PixelBuildProgressProps extends Omit<ComponentProps<"div">, "children"> {
     /** Progress, from 0 to `max`. The wall follows it, adding bricks one at a time. @default 0 */
     value?: number;
     /** Value that counts as complete. @default 100 */
     max?: number;
     /** Play a scripted run of about 30 seconds: build, stall at 99%, finish. Ignores `value`. @default false */
     autoplay?: boolean;
     /** Progress is unknown: workers shuttle bricks back and forth and the wall does not advance. @default false */
     indeterminate?: boolean;
     /** Captions by progress range, in ascending order of `until`. The last one shows from there on. @default installing, almost there, the 99% stall and done */
     messages?: PixelBuildMessage[];
     /** While `value` sits exactly here, the workers sit down and wait. Autoplay stalls at 99 by itself. */
     stallAt?: number;
     /** After finishing, crumble the wall and start the next update. In controlled use the next build starts once `value` drops below `max`. @default false */
     loop?: boolean;
     /** Number of the current update, shown in the first caption from the second update on. @default 1 */
     updateIndex?: number;
     /** How many updates there are in total, for the caption. @default 47 */
     updateTotal?: number;
     /** Size of one scene pixel: 2, 3 or 4 screen pixels. Narrow containers step down by themselves. @default "md" */
     size?: "sm" | "md" | "lg";
     /** Colors to override in the scene. */
     palette?: PixelBuildPalette;
     /** Called once each time progress reaches `max`. */
     onComplete?: () => void;
   }
   
   const W = 240;
   const H = 40;
   const GROUND = 34;
   const BRICK_W = 6;
   const BRICK_H = 3;
   const ROWS = 6;
   const COLS = 34;
   const WALL_X = 6;
   const WALL_TOP = GROUND - ROWS * BRICK_H;
   const TOTAL = COLS * ROWS;
   const PILE_X = 214;
   const SCALE = { sm: 2, md: 3, lg: 4 } as const;
   
   const COLORS = {
     k: "#1d2130",
     s: "#f2c29b",
     h: "#ffc94d",
     v: "#f47b20",
     p: "#33507a",
     b: "#b5533c",
     g: "#8a93a6",
     m: "#f4f4f5",
   } as const;
   
   // Worker frames, 8×10, facing right. One character per pixel.
   const WORKER_FRAMES: string[][] = [
     /* 0 walk a */ ["..hhhh..", ".hhhhhh.", "..ssss..", "..ssks..", ".vvvvv..", ".vvvvvs.", ".vvvvv..", "..pppp..", "..p..p..", ".kk..kk."],
     /* 1 walk b */ ["..hhhh..", ".hhhhhh.", "..ssss..", "..ssks..", ".vvvvv..", "svvvvv..", ".vvvvv..", "..pppp..", "...pp...", "...kk..."],
     /* 2 walk c */ ["..hhhh..", ".hhhhhh.", "..ssss..", "..ssks..", ".vvvvv..", ".vvvvvs.", ".vvvvv..", "..pppp..", ".p....p.", "kk....kk"],
     /* 3 carry a */ ["..hhhh..", ".hhhhhh.", "..ssss..", "..ssks..", ".vvvvvbb", ".vvvvsbb", ".vvvvv..", "..pppp..", "..p..p..", ".kk..kk."],
     /* 4 carry b */ ["..hhhh..", ".hhhhhh.", "..ssss..", "..ssks..", ".vvvvvbb", ".vvvvsbb", ".vvvvv..", "..pppp..", "...pp...", "...kk..."],
     /* 5 hammer up */ ["..hhhh.g", ".hhhhhhg", "..ssss.k", "..ssksk.", ".vvvvs..", ".vvvvv..", ".vvvvv..", "..pppp..", "..p..p..", ".kk..kk."],
     /* 6 hammer down */ ["..hhhh..", ".hhhhhh.", "..ssss..", "..ssks..", ".vvvvskg", ".vvvvv.g", ".vvvvv..", "..pppp..", "..p..p..", ".kk..kk."],
     /* 7 sit */ ["........", "........", "..hhhh..", ".hhhhhh.", "..ssss..", "..ssks..", ".vvvvv..", ".vvvvvs.", ".vvpppp.", ".kkpppkk"],
     /* 8 sit, mug up */ ["........", "........", "..hhhh..", ".hhhhhh.", "..ssss..", "..ssksm.", ".vvvvvs.", ".vvvvv..", ".vvpppp.", ".kkpppkk"],
     /* 9 sit, foot up */ ["........", "........", "..hhhh..", ".hhhhhh.", "..ssss..", "..ssks..", ".vvvvv..", ".vvvvvs.", ".vvppppk", ".kkppp.k"],
     /* 10 asleep */ ["........", "........", "........", "..hhhh..", ".hhhhhh.", "..ssss..", "..skks..", ".vvvvv..", ".vvpppp.", ".kkpppkk"],
     /* 11 cheer */ ["s.hhhh.s", "shhhhhhs", "v.ssss.v", ".vssksv.", ".vvvvv..", "..vvvv..", "..vvvv..", "..pppp..", "..p..p..", ".kk..kk."],
   ];
   
   const CLOUD_FRAMES = [
     ["...wwww.....", ".wwwwwwww...", "wwwwwwwwwww.", ".wwwwwwwwwww", "............"],
     ["..www.......", ".wwwwwww....", "wwwwwwwww...", "............", "............"],
   ];
   
   const DIGITS: Record<string, string[]> = {
     "0": ["111", "101", "101", "101", "111"],
     "1": ["010", "110", "010", "010", "111"],
     "2": ["111", "001", "111", "100", "111"],
     "3": ["111", "001", "111", "001", "111"],
     "4": ["101", "101", "111", "001", "001"],
     "5": ["111", "100", "111", "001", "111"],
     "6": ["111", "100", "111", "101", "111"],
     "7": ["111", "001", "010", "010", "010"],
     "8": ["111", "101", "111", "101", "111"],
     "9": ["111", "101", "111", "001", "111"],
     "%": ["101", "001", "010", "100", "101"],
     ok: ["....1", "...1.", "1.1..", ".1...", "....."],
   };
   
   const DEFAULT_SKY: [string, string, string] = ["#8fd0ff", "#a9dcff", "#c6e9ff"];
   const DEFAULT_BRICK: [string, string] = ["#b5533c", "#9c4530"];
   
   /** A small seeded generator (mulberry32). */
   function seededRandom(seed: number) {
     let a = seed >>> 0;
     return () => {
       a = (a + 0x6d2b79f5) >>> 0;
       let t = a;
       t = Math.imul(t ^ (t >>> 15), t | 1);
       t ^= t + Math.imul(t ^ (t >>> 7), t | 61);
       return ((t ^ (t >>> 14)) >>> 0) / 4294967296;
     };
   }
   
   /** Where the scripted run wants progress to be, t seconds in. */
   function scripted(t: number) {
     if (t < 8) return (t / 8) * 40;
     if (t < 18) return 40 + ((t - 8) / 10) * 58;
     if (t < 19) return 98 + (t - 18);
     if (t < 25) return 99;
     return 100;
   }
   
   function captionFor(percent: number, messages: PixelBuildMessage[] | undefined, cycle: number, total: number) {
     const list = messages ?? [
       { until: 40, text: cycle > 1 ? `Installing update ${cycle} of ${total}` : "Installing update…" },
       { until: 99, text: "Almost there…" },
       { until: 100, text: "99%. Any minute now." },
       { until: Infinity, text: "Done!" },
     ];
     return (list.find((message) => percent < message.until) ?? list[list.length - 1])?.text ?? "";
   }
   
   export function PixelBuildProgress({
     value = 0,
     max = 100,
     autoplay = false,
     indeterminate = false,
     messages,
     stallAt,
     loop = false,
     updateIndex = 1,
     updateTotal = 47,
     size = "md",
     palette,
     onComplete,
     className,
     ...props
   }: PixelBuildProgressProps) {
     const hostRef = useRef<HTMLDivElement>(null);
     const canvasRef = useRef<HTMLCanvasElement>(null);
     /** Whole percent on screen. It changes at most a hundred times per build, never per frame. */
     const [percent, setPercent] = useState(() => (autoplay ? 0 : Math.round((Math.min(Math.max(value, 0), max) / max) * 100)));
     /** Updates finished since mount, added to `updateIndex`. */
     const [loops, setLoops] = useState(0);
     const cycle = updateIndex + loops;
     const caption = indeterminate ? "Working…" : captionFor((percent / 100) * max, messages, cycle, updateTotal);
   
     const latest = useRef({ value, max, autoplay, indeterminate, stallAt, loop, onComplete });
     useEffect(() => {
       latest.current = { value, max, autoplay, indeterminate, stallAt, loop, onComplete };
     });
     const redraw = useRef<() => void>(() => {});
     useEffect(() => {
       redraw.current();
     }, [value, max, indeterminate, autoplay]);
   
     const sky = palette?.sky ?? DEFAULT_SKY;
     const brick = palette?.brick ?? DEFAULT_BRICK;
     const mortar = palette?.mortar ?? "#e2d3bd";
     const ground = palette?.ground ?? "#c79a5b";
     const vest = palette?.vest ?? COLORS.v;
     const helmet = palette?.helmet ?? COLORS.h;
     const sceneKey = [...sky, ...brick, mortar, ground, vest, helmet].join("|");
   
     useEffect(() => {
       const host = hostRef.current;
       const canvas = canvasRef.current;
       const ctx = canvas?.getContext("2d");
       const buffer = createPixelBuffer(W, H);
       if (!host || !canvas || !ctx || !buffer) return;
       const b = buffer.ctx;
       const colors = sceneKey.split("|");
       const [sky0, sky1, sky2, brick0, brick1, mortarColor, groundColor, vestColor, helmetColor] = colors;
       const workers: SpriteSheet = spriteSheet(WORKER_FRAMES, { ...COLORS, v: vestColor, h: helmetColor });
       const clouds = spriteSheet(CLOUD_FRAMES, { w: "#ffffff" });
       const random = seededRandom(230);
       const reduced = window.matchMedia("(prefers-reduced-motion: reduce)");
   
       // Scene state. Everything here lives outside React.
       let scale = SCALE[size];
       let view = W;
       let compact = false;
       let shown = latest.current.autoplay ? 0 : (Math.min(Math.max(latest.current.value, 0), latest.current.max) / latest.current.max) * 100;
       let clock = 0;
       let time = 0;
       let doneFor = -1;
       let crumbling = -1;
       let waitingForReset = false;
       let wasStalled = false;
       let jumpUntil = 0;
       let lastPercent = -1;
       /** Seconds the carriers have spent walking. They only walk while there is work. */
       let walk = 0;
       // Fallen bricks: position, velocity, time until each pops, bounces left.
       const fx = new Float32Array(TOTAL);
       const fy = new Float32Array(TOTAL);
       const fvx = new Float32Array(TOTAL);
       const fvy = new Float32Array(TOTAL);
       const fpop = new Float32Array(TOTAL);
       const fstate = new Uint8Array(TOTAL);
       const dust: { x: number; y: number; age: number }[] = [];
   
       const brickCell = (index: number) => {
         const col = Math.floor(index / ROWS);
         const row = index % ROWS;
         // Running bond: every other course is shifted half a brick.
         return { x: WALL_X + col * BRICK_W + (row % 2 ? BRICK_W / 2 : 0), y: GROUND - (row + 1) * BRICK_H, tone: (col * 7 + row * 3) % 5 < 2 ? 1 : 0 };
       };
   
       function text(glyphs: string[], x: number, y: number, color: string) {
         b.fillStyle = color;
         let cursor = x;
         for (const glyph of glyphs) {
           const rows = DIGITS[glyph];
           if (!rows) continue;
           for (let r = 0; r < rows.length; r++) for (let c = 0; c < rows[r].length; c++) if (rows[r][c] === "1") b.fillRect(cursor + c, y + r, 1, 1);
           cursor += rows[0].length + 1;
         }
       }
   
       function startCrumble() {
         crumbling = 0;
         dust.length = 0;
         for (let i = 0; i < TOTAL; i++) {
           const cell = brickCell(i);
           fx[i] = cell.x;
           fy[i] = cell.y;
           fvx[i] = (random() - 0.5) * 60;
           fvy[i] = -20 - random() * 45;
           fpop[i] = random() * 1.9;
           fstate[i] = 0;
         }
       }
   
       function advance(dt: number) {
         const now = latest.current;
         time += dt;
         const target = now.autoplay ? scripted(clock) : (Math.min(Math.max(now.value, 0), now.max) / now.max) * 100;
         const stalled = !now.indeterminate && (now.autoplay ? clock >= 19 && clock < 25 : now.stallAt !== undefined && now.value === now.stallAt && Math.abs(shown - target) < 0.5);
         if (wasStalled && !stalled) jumpUntil = time + 0.45;
         wasStalled = stalled;
         if (now.indeterminate || (!stalled && doneFor < 0 && crumbling < 0 && !waitingForReset)) walk += dt;
   
         if (crumbling >= 0) {
           crumbling += dt;
           for (let i = 0; i < TOTAL; i++) {
             if (fstate[i] === 0) {
               if (crumbling < fpop[i]) continue;
               fstate[i] = 1;
             }
             if (fstate[i] === 4) continue;
             fvy[i] += 170 * dt;
             fx[i] += fvx[i] * dt;
             fy[i] += fvy[i] * dt;
             if (fy[i] >= GROUND - 2) {
               fy[i] = GROUND - 2;
               if (fstate[i] === 1 && dust.length < 28) dust.push({ x: fx[i], y: GROUND - 1, age: 0 });
               fvy[i] *= -0.38;
               fvx[i] *= 0.55;
               fstate[i] += 1;
             }
           }
           for (const puff of dust) puff.age += dt;
           if (crumbling > 3.6) {
             crumbling = -1;
             doneFor = -1;
             shown = 0;
             clock = 0;
             waitingForReset = !now.autoplay;
             setLoops((n) => n + 1);
           }
           return stalled;
         }
   
         if (waitingForReset) {
           // The next build starts once the caller's value has gone back below max.
           if (target < 100) waitingForReset = false;
           return stalled;
         }
         if (now.autoplay && !(doneFor >= 0 && !now.loop)) clock += dt;
         if (!now.indeterminate) {
           // Bricks go on one at a time: progress never jumps more than a quarter of the wall per second.
           const stepLimit = 26 * dt;
           shown += Math.min(Math.max(target - shown, -stepLimit * 3), stepLimit);
         }
         if (shown >= 99.999 && doneFor < 0) {
           shown = 100;
           doneFor = 0;
           now.onComplete?.();
         } else if (shown < 99.999 && doneFor >= 0 && !now.autoplay) {
           doneFor = -1;
         }
         if (doneFor >= 0) {
           doneFor += dt;
           if (now.loop && doneFor > 2.4) startCrumble();
         }
         return stalled;
       }
   
       function draw(stalled: boolean, still: boolean) {
         const now = latest.current;
         const placed = crumbling >= 0 ? TOTAL : Math.min(TOTAL, Math.floor((shown / 100) * TOTAL + 0.0001));
         const frontCol = Math.min(COLS, Math.floor(placed / ROWS));
         const frontX = WALL_X + frontCol * BRICK_W;
         const done = doneFor >= 0 && crumbling < 0;
         const building = !done && !stalled && crumbling < 0 && !waitingForReset && !still;
   
         // Sky, sun and clouds.
         b.fillStyle = sky0;
         b.fillRect(0, 0, W, 12);
         b.fillStyle = sky1;
         b.fillRect(0, 12, W, 11);
         b.fillStyle = sky2;
         b.fillRect(0, 23, W, GROUND - 23);
         b.fillStyle = "#ffe07a";
         b.fillRect(17, 4, 5, 7);
         b.fillRect(16, 5, 7, 5);
         b.fillStyle = "#fff3c4";
         b.fillRect(18, 5, 2, 2);
         const drift = still ? 0 : time;
         drawSprite(b, clouds, 0, ((40 + drift * 4) % (W + 14)) - 14, 3);
         drawSprite(b, clouds, 1, ((150 + drift * 2.6) % (W + 14)) - 14, 9);
         drawSprite(b, clouds, 1, ((90 + drift * 3.3) % (W + 14)) - 14, 1);
   
         // Power poles and their wire.
         b.fillStyle = "#6b4a2f";
         for (const x of [86, 168]) {
           b.fillRect(x, 9, 1, GROUND - 9);
           b.fillRect(x - 2, 10, 5, 1);
         }
         b.fillStyle = "#3d3a45";
         for (let x = 0; x < W; x += 2) b.fillRect(x, 11 + (Math.abs(((x + 80) % 82) - 41) < 20 ? 1 : 0), 1, 1);
   
         // The small green building at the far right.
         b.fillStyle = "#2f8f57";
         b.fillRect(222, 13, 16, GROUND - 13);
         b.fillStyle = "#3fae6b";
         b.fillRect(223, 14, 14, GROUND - 14);
         b.fillStyle = "#24774a";
         b.fillRect(221, 12, 18, 2);
         b.fillStyle = "#d9f7e4";
         for (let y = 17; y < 29; y += 5) for (let x = 225; x < 236; x += 4) b.fillRect(x, y, 2, 2);
         b.fillStyle = "#1d2130";
         b.fillRect(229, 29, 3, 5);
   
         // Ground.
         b.fillStyle = groundColor;
         b.fillRect(0, GROUND, W, H - GROUND);
         b.fillStyle = "rgb(0 0 0 / 0.14)";
         b.fillRect(0, GROUND, W, 1);
         for (let x = 3; x < W; x += 11) b.fillRect(x + ((x * 7) % 5), GROUND + 2 + ((x * 3) % 3), 2, 1);
   
         // The wall: mortar first, then bricks in two batches, one per tone.
         if (crumbling < 0 && placed > 0) {
           b.fillStyle = mortarColor;
           const full = Math.floor(placed / ROWS);
           if (full > 0) b.fillRect(WALL_X, WALL_TOP, full * BRICK_W, ROWS * BRICK_H);
           if (placed % ROWS) b.fillRect(WALL_X + full * BRICK_W, GROUND - (placed % ROWS) * BRICK_H, BRICK_W, (placed % ROWS) * BRICK_H);
         }
         for (let tone = 0; tone < 2; tone++) {
           b.fillStyle = tone ? brick1 : brick0;
           for (let i = 0; i < placed; i++) {
             const cell = brickCell(i);
             if (cell.tone !== tone) continue;
             if (crumbling >= 0) {
               if (fstate[i] === 0) b.fillRect(cell.x, cell.y, BRICK_W - 1, BRICK_H - 1);
               else b.fillRect(Math.round(fx[i]), Math.round(fy[i]), 4, 2);
             } else {
               const right = Math.min(cell.x + BRICK_W - 1, WALL_X + (frontCol + 1) * BRICK_W - 1);
               b.fillRect(cell.x, cell.y, right - cell.x, BRICK_H - 1);
             }
           }
         }
         b.fillStyle = "rgb(120 110 100 / 0.5)";
         for (const puff of dust) {
           if (puff.age > 0.5) continue;
           const spread = Math.round(puff.age * 8);
           b.fillRect(Math.round(puff.x) - spread, puff.y - Math.round(puff.age * 4), 1, 1);
           b.fillRect(Math.round(puff.x) + 2 + spread, puff.y - 1 - Math.round(puff.age * 3), 1, 1);
         }
   
         // The pile of bricks the carriers fetch from.
         b.fillStyle = brick1;
         b.fillRect(PILE_X - 5, GROUND - 2, 9, 2);
         b.fillStyle = brick0;
         b.fillRect(PILE_X - 3, GROUND - 4, 6, 2);
   
         const site = crumbling < 0 && !done;
         const scaffoldX = Math.min(frontX + 1, PILE_X - 22);
         if (site) {
           // Scaffold at the build front.
           b.fillStyle = "#6f7890";
           b.fillRect(scaffoldX, WALL_TOP - 3, 1, GROUND - WALL_TOP + 3);
           b.fillRect(scaffoldX + 9, WALL_TOP - 3, 1, GROUND - WALL_TOP + 3);
           b.fillStyle = "#b98a4f";
           b.fillRect(scaffoldX - 1, WALL_TOP + 7, 12, 1);
           b.fillRect(scaffoldX - 1, GROUND - 5, 12, 1);
           // Crane: mast, jib, cable and a brick on the hook.
           if (!compact) {
             const mast = Math.min(scaffoldX + 16, W - 30);
             b.fillStyle = helmetColor;
             b.fillRect(mast, 3, 2, GROUND - 3);
             b.fillRect(mast - 24, 3, 32, 1);
             b.fillRect(mast - 2, 5, 6, 3);
             b.fillStyle = "#1d2130";
             for (let y = 6; y < GROUND; y += 4) b.fillRect(mast, y, 2, 1);
             b.fillRect(mast - 24, 4, 1, 1);
             const hookX = Math.max(mast - 22, Math.min(frontX + 2, mast - 6));
             const nextRow = placed % ROWS;
             const landing = GROUND - (nextRow + 1) * BRICK_H - 1;
             const cycleT = building ? (time * 0.9) % 1 : 0.4;
             const hookY = 5 + (landing - 5) * Math.min(1, cycleT * 1.4);
             b.fillRect(hookX + 1, 4, 1, Math.max(1, Math.round(hookY) - 4));
             b.fillStyle = brick0;
             b.fillRect(hookX - 1, Math.round(hookY), 5, 2);
           }
         }
   
         // Workers.
         const jumping = time < jumpUntil;
         const hop = (phase: number) => (done || jumping ? -Math.round(Math.abs(Math.sin(time * 9 + phase)) * 2) : 0);
         const pose = (index: number, x: number, y: number, frame: number, flip = false) => drawSprite(b, workers, frame, x, y + hop(index), { flip });
         const beat = Math.floor(time * 4) % 2;
         const feet = GROUND - 10;
         // The mason hammers at the front.
         const masonX = Math.max(1, Math.min(frontX - 7, W - 30));
         if (done || jumping) pose(0, masonX, feet, 11);
         else if (stalled) pose(0, masonX, feet, 10);
         else pose(0, masonX, feet, still ? 6 : 5 + beat, false);
         // Carriers walk bricks from the pile to the front and come back empty.
         const count = compact ? 1 : 2;
         const dropX = Math.min(scaffoldX + 12, PILE_X - 12);
         const span = Math.max(8, PILE_X - 8 - dropX);
         for (let i = 0; i < count; i++) {
           const t = (i * 0.5 + (still ? 0.2 : walk * 0.11)) % 1;
           const toFront = t < 0.5;
           const along = toFront ? t * 2 : (t - 0.5) * 2;
           const x = toFront ? PILE_X - 8 - along * span : dropX + along * span;
           const step = Math.floor(time * 7 + i) % 4;
           if (done || jumping) pose(1 + i, x, feet, 11);
           else if (stalled) pose(1 + i, x, feet, i === 0 ? 7 + (Math.floor(time * 0.8) % 2) : 7 + (Math.floor(time * 3) % 2) * 2);
           else if (toFront || now.indeterminate) pose(1 + i, x, feet, still ? 3 : 3 + (step % 2), toFront);
           else pose(1 + i, x, feet, still ? 0 : [0, 1, 2, 1][step]);
         }
         if (!compact && site) {
           // One more on the scaffold, and a foreman by the building.
           if (stalled) pose(3, scaffoldX + 1, WALL_TOP - 3, 7);
           else pose(3, scaffoldX + 1, WALL_TOP - 3, done || jumping ? 11 : still ? 6 : 5 + (1 - beat), true);
         }
         if (!compact) {
           const foremanX = 196 + (still ? 0 : Math.round(Math.sin(time * 0.5) * 5));
           if (done || jumping) pose(4, foremanX, feet, 11);
           else if (stalled) pose(4, foremanX, feet, 7);
           else pose(4, foremanX, feet, still ? 0 : [0, 1, 2, 1][Math.floor(time * 3) % 4], Math.cos(time * 0.5) < 0);
         }
         // Zzz over the sleeper.
         if (stalled && !still) {
           b.fillStyle = "#1d2130";
           const rise = Math.floor(time * 2) % 3;
           for (let i = 0; i <= rise; i++) {
             const zx = masonX + 8 + i * 3;
             const zy = feet - 1 - i * 3;
             b.fillRect(zx, zy, 3, 1);
             b.fillRect(zx + 1, zy + 1, 1, 1);
             b.fillRect(zx, zy + 2, 3, 1);
           }
         }
   
         // The sign rides above the front with the percent, or a check when done.
         if (!now.indeterminate && crumbling < 0) {
           const glyphs = done ? ["ok"] : [...String(Math.min(99, Math.floor(shown))), "%"];
           const width = glyphs.reduce((sum, glyph) => sum + (DIGITS[glyph]?.[0].length ?? 0) + 1, 0) + 3;
           const signX = Math.max(1, Math.min(frontX - Math.floor(width / 2), W - width - 1));
           b.fillStyle = "#1d2130";
           b.fillRect(signX + Math.floor(width / 2), 10, 1, WALL_TOP - 9);
           b.fillRect(signX, 1, width, 9);
           b.fillStyle = done ? "#d9f7e4" : "#ffffff";
           b.fillRect(signX + 1, 2, width - 2, 7);
           text(glyphs, signX + 2, 3, done ? "#24774a" : "#1d2130");
         }
   
         // Blit: a whole number of screen pixels per scene pixel, following the build front when cropped.
         const camera = Math.round(Math.max(0, Math.min(W - view, frontX - view / 2)));
         ctx!.imageSmoothingEnabled = false;
         ctx!.clearRect(0, 0, canvas!.width, canvas!.height);
         ctx!.drawImage(buffer!.canvas, camera, 0, view, H, 0, 0, view, H);
   
         const whole = now.indeterminate ? lastPercent : Math.round(Math.min(100, Math.max(0, crumbling >= 0 ? 100 : shown)));
         if (whole !== lastPercent) {
           lastPercent = whole;
           setPercent(whole);
         }
       }
   
       const loopHandle = runCanvasLoop({
         host,
         canvas,
         resize: (frame) => {
           // Pick the largest whole-number scale that still shows a useful stretch of the site, then
           // size the canvas in scene pixels; CSS scales it up with image-rendering: pixelated.
           scale = SCALE[size];
           while (scale > 1 && frame.width / scale < 96) scale -= 1;
           view = Math.max(40, Math.min(W, Math.floor(frame.width / scale)));
           compact = frame.width < 360;
           canvas.width = view;
           canvas.height = H;
           canvas.style.width = `${view * scale}px`;
           canvas.style.height = `${H * scale}px`;
           host.style.height = `${H * scale}px`;
         },
         render: (frame) => {
           if (frame.still) {
             // Reduced motion: a still scene at the current value.
             const now = latest.current;
             if (!now.autoplay) shown = (Math.min(Math.max(now.value, 0), now.max) / now.max) * 100;
             crumbling = -1;
             draw(false, true);
             return;
           }
           const stalled = advance(frame.dt);
           draw(stalled, false);
         },
       });
       redraw.current = () => {
         loopHandle.wake();
         loopHandle.redraw();
       };
   
       // Under reduced motion the frame loop is off, so a scripted run steps once a second instead.
       const stepper = window.setInterval(() => {
         if (!reduced.matches || !latest.current.autoplay) return;
         clock += 1;
         if (clock > 28) {
           if (!latest.current.loop) clock = 28;
           else {
             clock = 0;
             setLoops((n) => n + 1);
           }
         }
         const before = shown;
         shown = scripted(clock);
         if (shown >= 100 && before < 100) latest.current.onComplete?.();
         loopHandle.redraw();
       }, 1000);
   
       return () => {
         window.clearInterval(stepper);
         redraw.current = () => {};
         loopHandle.dispose();
       };
     }, [size, sceneKey]);
   
     const scale = SCALE[size];
     return (
       <div className={cn("flex w-full flex-col items-center gap-4", className)} {...props}>
         <div
           role="progressbar"
           aria-label="Update progress"
           aria-valuemin={0}
           aria-valuemax={max}
           aria-valuenow={indeterminate ? undefined : Math.round((percent / 100) * max)}
           aria-valuetext={caption}
           style={{ maxWidth: W * scale + 16 }}
           className="w-full rounded-full bg-[#f6eedd] p-2 shadow-[inset_0_2px_3px_rgb(255_255_255/0.9),inset_0_-2px_4px_rgb(120_90_40/0.18),0_10px_24px_-12px_rgb(60_40_10/0.4)]"
         >
           <div ref={hostRef} style={{ height: H * scale }} className="relative flex w-full justify-center overflow-hidden rounded-full bg-[#a9dcff] shadow-[inset_0_2px_6px_rgb(0_0_0/0.28)]">
             <canvas ref={canvasRef} aria-hidden="true" className="block [image-rendering:pixelated]" />
             <span aria-hidden="true" className="pointer-events-none absolute inset-0 rounded-full shadow-[inset_0_2px_6px_rgb(0_0_0/0.28)]" />
           </div>
         </div>
         <p aria-live="polite" className="min-h-5 text-center text-sm font-medium text-foreground">
           {caption}
         </p>
       </div>
     );
   }

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