05A Dithered Pond Where Wave-Equation Ripples Are Stamped in Four Tones
The height field is updated from neighbor averages and the previous frame to spread ripples, then split into four levels and stamped with a Bayer matrix.
Best forWater hero scenes and click reactive backgrounds
DAMPINGWAVE_CLEVELSDROP_EVERY
<main class="stage">
<div class="sc is-demo" id="scRoot">
<canvas class="sc__canvas" id="scCanvas" width="480" height="300" tabindex="0" aria-label="A Dithered Pond Where Wave-Equation Ripples Are Stamped in Four Tones"></canvas>
<p class="sc__status" id="scStatus" aria-live="polite">Raindrops fall — ripples stamped in four tones</p>
<button class="sc__btn" id="scBtn" type="button">Pause</button>
<p class="sc__caption">A Dithered Pond Where Wave-Equation Ripples Are Stamped in Four Tones</p>
</div>
</main>@use "../../../../site/static/demo-tokens" as *;
@include stage($stage-ink);
.sc {
position: relative;
width: min(92vw, calc(160vh - 12.8vw));
aspect-ratio: 480 / 300;
margin: 0 auto;
border-radius: $r-card;
overflow: hidden;
box-shadow: $shadow-raised;
background: $subject-ink;
}
.sc__canvas {
display: block;
width: 100%;
height: 100%;
touch-action: none;
image-rendering: pixelated;
}
.sc__canvas:focus-visible {
outline: 2px solid rgba(255, 255, 255, .85);
outline-offset: -6px;
}
.sc__status {
position: absolute;
left: $sp-3;
top: $sp-3;
max-width: 62%;
margin: 0;
padding: $sp-1 $sp-3;
border-radius: $r-pill;
background: rgba(255, 255, 255, .85);
color: $subject-ink;
font-weight: 500;
font-size: 11px;
line-height: 1.4;
pointer-events: none;
}
.sc__btn {
position: absolute;
right: $sp-3;
bottom: $sp-3;
margin: 0;
padding: $sp-1 $sp-3;
border: 0;
border-radius: $r-pill;
background: rgba(255, 255, 255, .85);
color: $subject-ink;
font: inherit;
font-weight: 500;
font-size: 12px;
line-height: 1.4;
cursor: pointer;
}
.sc__btn:focus-visible {
outline: 2px solid #ffffff;
outline-offset: 2px;
}
.sc__caption {
position: absolute;
left: $sp-3;
bottom: $sp-3;
max-width: 68%;
margin: 0;
padding: $sp-1 $sp-3;
border-radius: $r-pill;
background: rgba(255, 255, 255, .85);
color: $subject-ink;
font-weight: 500;
font-size: 12px;
line-height: 1.4;
pointer-events: none;
}
@media (max-width: 340px) {
.sc__caption, .sc__btn { font-size: 10px; padding: $sp-1 $sp-2; }
.sc__status { font-size: 10px; }
}
@media (prefers-reduced-motion: reduce) {
.sc { cursor: default; }
}html, body {
margin: 0;
overflow: hidden;
}
.stage {
box-sizing: border-box;
min-height: 100vh;
display: grid;
place-items: center;
margin: 0;
background: #17141a;
font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
padding: clamp(8px, 4vw, 24px);
}
.sc {
position: relative;
width: min(92vw, 160vh - 12.8vw);
aspect-ratio: 480/300;
margin: 0 auto;
border-radius: 16px;
overflow: hidden;
box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
background: #17141a;
}
.sc__canvas {
display: block;
width: 100%;
height: 100%;
touch-action: none;
image-rendering: pixelated;
}
.sc__canvas:focus-visible {
outline: 2px solid rgba(255, 255, 255, 0.85);
outline-offset: -6px;
}
.sc__status {
position: absolute;
left: 12px;
top: 12px;
max-width: 62%;
margin: 0;
padding: 4px 12px;
border-radius: 999px;
background: rgba(255, 255, 255, 0.85);
color: #17141a;
font-weight: 500;
font-size: 11px;
line-height: 1.4;
pointer-events: none;
}
.sc__btn {
position: absolute;
right: 12px;
bottom: 12px;
margin: 0;
padding: 4px 12px;
border: 0;
border-radius: 999px;
background: rgba(255, 255, 255, 0.85);
color: #17141a;
font: inherit;
font-weight: 500;
font-size: 12px;
line-height: 1.4;
cursor: pointer;
}
.sc__btn:focus-visible {
outline: 2px solid #ffffff;
outline-offset: 2px;
}
.sc__caption {
position: absolute;
left: 12px;
bottom: 12px;
max-width: 68%;
margin: 0;
padding: 4px 12px;
border-radius: 999px;
background: rgba(255, 255, 255, 0.85);
color: #17141a;
font-weight: 500;
font-size: 12px;
line-height: 1.4;
pointer-events: none;
}
@media (max-width: 340px) {
.sc__caption, .sc__btn {
font-size: 10px;
padding: 4px 8px;
}
.sc__status {
font-size: 10px;
}
}
@media (prefers-reduced-motion: reduce) {
.sc {
cursor: default;
}
}(function () {
const W = 480;
const H = 300;
const PI2 = Math.PI * 2;
const FIXED_DT = 16;
const REDUCE_STEP_MS = 900;
const KEY_STEP = 14;
const IDLE_TICKS = 150;
const BTN_PAUSE = 'Pause';
const BTN_PLAY = 'Play';
const BTN_NEXT = 'Next scene';
// 점을 찍는 작은 격자 — 화면에는 3배로 확대해 올린다
const GW = 160;
const GH = 100;
function clamp(v, lo, hi) { return v < lo ? lo : (v > hi ? hi : v); }
function lerp(a, b, k) { return a + (b - a) * k; }
function smooth(x) { const c = clamp(x, 0, 1); return c * c * (3 - 2 * c); }
function frac(x) { return x - Math.floor(x); }
// 시드 고정 난수 — 같은 시드면 언제나 같은 수열 (선형 합동 방식)
function lcg(seed) {
let s = seed >>> 0;
return function () {
s = (Math.imul(s, 1664525) + 1013904223) >>> 0;
return s / 4294967296;
};
}
// 좌표 두 개와 시드로 0 이상 1 미만의 값을 만드는 정수 해시 (난수 함수 없이도 같은 좌표는 늘 같은 값)
function hash2(x, y, seed) {
let h = (Math.imul(x | 0, 374761393) + Math.imul(y | 0, 668265263) + Math.imul(seed | 0, 1442695041)) | 0;
h = Math.imul(h ^ (h >>> 13), 1274126177);
h ^= h >>> 16;
return (h >>> 0) / 4294967296;
}
// 격자 네 점의 해시를 smooth 로 이어 붙인 값 노이즈
function vnoise(x, y, seed) {
const xi = Math.floor(x);
const yi = Math.floor(y);
const fx = smooth(x - xi);
const fy = smooth(y - yi);
const a = lerp(hash2(xi, yi, seed), hash2(xi + 1, yi, seed), fx);
const b = lerp(hash2(xi, yi + 1, seed), hash2(xi + 1, yi + 1, seed), fx);
return lerp(a, b, fy);
}
// 베이어 임계 행렬 — n 은 2 의 거듭제곱. 값은 0 초과 1 미만으로 맞춘다
function makeBayer(n) {
let size = 2;
let m = [0, 2, 3, 1];
const quad = [0, 2, 3, 1];
while (size < n) {
const s2 = size * 2;
const next = [];
for (let y = 0; y < s2; y += 1) {
for (let x = 0; x < s2; x += 1) {
const q = (y >= size ? 2 : 0) + (x >= size ? 1 : 0);
next.push(4 * m[(y % size) * size + (x % size)] + quad[q]);
}
}
m = next;
size = s2;
}
const out = new Float32Array(n * n);
for (let i = 0; i < out.length; i += 1) {
out[i] = (m[i] + 0.5) / (n * n);
}
return out;
}
// 색 하나를 캔버스 픽셀 한 개(리틀 엔디언 RGBA)로 묶는다
function pack(c) {
return ((255 << 24) | (Math.round(c[2]) << 16) | (Math.round(c[1]) << 8) | Math.round(c[0])) >>> 0;
}
function mixPack(a, b, k) {
return pack([lerp(a[0], b[0], k), lerp(a[1], b[1], k), lerp(a[2], b[2], k)]);
}
function makeBuf() {
const off = document.createElement('canvas');
off.width = GW;
off.height = GH;
const octx = off.getContext('2d');
if (!octx) {
throw new Error('2d context unavailable');
}
const img = octx.createImageData(GW, GH);
return { off: off, octx: octx, img: img, px: new Uint32Array(img.data.buffer) };
}
// 작은 격자를 큰 캔버스에 보간 없이 확대해 올린다
function flush(ctx, b) {
b.octx.putImageData(b.img, 0, 0);
ctx.imageSmoothingEnabled = false;
ctx.drawImage(b.off, 0, 0, W, H);
}
function start(root, canvas, statusEl, btnEl, make) {
const ctx0 = canvas.getContext('2d');
if (!ctx0) {
return function () { return; };
}
const ctx = ctx0;
const dpr = Math.min(window.devicePixelRatio || 1, 2);
canvas.width = Math.round(W * dpr);
canvas.height = Math.round(H * dpr);
ctx.setTransform(dpr, 0, 0, dpr, 0, 0);
const reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
const inp = { x: W / 2, y: H / 2, idle: 99999 };
const scene = make(inp, reduce);
let paused = false;
let rafId = 0;
let lastTs = -1;
let accMs = 0;
let lastLabel = '';
const cleaners = [];
function listen(target, type, fn) {
target.addEventListener(type, fn);
cleaners.push(function () { target.removeEventListener(type, fn); });
}
function show() {
scene.draw(ctx);
const t = scene.label();
if (t !== lastLabel) {
lastLabel = t;
statusEl.textContent = t;
}
}
function advance(ms) {
const n = Math.round(ms / FIXED_DT);
for (let i = 0; i < n; i += 1) {
inp.idle += 1;
scene.step();
}
}
function refresh() {
if (reduce) {
advance(FIXED_DT * 6);
show();
}
}
function toLocal(e) {
const r = canvas.getBoundingClientRect();
inp.x = clamp((e.clientX - r.left) * W / r.width, 0, W);
inp.y = clamp((e.clientY - r.top) * H / r.height, 0, H);
inp.idle = 0;
}
function tick(ts) {
if (lastTs < 0) {
lastTs = ts;
}
const frameDt = Math.min(ts - lastTs, 160);
lastTs = ts;
if (!paused) {
accMs += frameDt;
while (accMs >= FIXED_DT) {
inp.idle += 1;
scene.step();
accMs -= FIXED_DT;
}
show();
}
rafId = requestAnimationFrame(tick);
}
btnEl.textContent = reduce ? BTN_NEXT : BTN_PAUSE;
if (reduce) {
root.classList.remove('is-demo');
advance(1400);
show();
}
listen(btnEl, 'click', function () {
if (reduce) {
advance(REDUCE_STEP_MS);
show();
return;
}
paused = !paused;
if (paused) {
root.classList.remove('is-demo');
}
else {
root.classList.add('is-demo');
}
btnEl.textContent = paused ? BTN_PLAY : BTN_PAUSE;
});
listen(canvas, 'pointermove', function (e) {
toLocal(e);
refresh();
});
listen(canvas, 'pointerdown', function (e) {
toLocal(e);
scene.tap();
refresh();
});
listen(canvas, 'keydown', function (e) {
const k = e.key;
let dx = 0;
let dy = 0;
if (k === 'Enter' || k === ' ') {
e.preventDefault();
scene.tap();
refresh();
return;
}
if (k === 'ArrowLeft') {
dx = -KEY_STEP;
}
else if (k === 'ArrowRight') {
dx = KEY_STEP;
}
else if (k === 'ArrowUp') {
dy = -KEY_STEP;
}
else if (k === 'ArrowDown') {
dy = KEY_STEP;
}
else {
return;
}
e.preventDefault();
inp.x = clamp(inp.x + dx, 0, W);
inp.y = clamp(inp.y + dy, 0, H);
inp.idle = 0;
refresh();
});
if (!reduce) {
rafId = requestAnimationFrame(tick);
}
return function () {
cancelAnimationFrame(rafId);
for (let i = 0; i < cleaners.length; i += 1) {
cleaners[i]();
}
};
}
const DAMPING = 0.985;
const WAVE_C = 0.4;
const LEVELS = 4;
const DROP_EVERY = 42;
const SUBSTEPS = 2;
const DROP_R = 3.2;
const DROP_AMP = 2.2;
const TONE_GAIN = 0.9;
const PALETTE_05 = [[42, 58, 99], [90, 127, 181], [159, 201, 234], [232, 246, 255]];
const TXT_RAIN = 'Raindrops fall — ripples stamped in four tones';
const TXT_DROP = 'The pointer drops water';
function makeScene(inp, reduce) {
const buf = makeBuf();
const matrix = makeBayer(8);
const pal = PALETTE_05.map(pack);
const rnd = lcg(453505);
let h = new Float32Array(GW * GH);
let hp = new Float32Array(GW * GH);
let hn = new Float32Array(GW * GH);
let t = 0;
let lastDrop = 0;
function drop(cx, cy, amp) {
const r = Math.ceil(DROP_R * 2);
for (let y = Math.max(1, Math.floor(cy) - r); y < Math.min(GH - 1, Math.floor(cy) + r + 1); y += 1) {
for (let x = Math.max(1, Math.floor(cx) - r); x < Math.min(GW - 1, Math.floor(cx) + r + 1); x += 1) {
const d2 = (x - cx) * (x - cx) + (y - cy) * (y - cy);
h[y * GW + x] += amp * Math.exp(-d2 / (DROP_R * DROP_R));
}
}
}
// 파동 방정식 한 걸음 — 이웃 합과 이전 프레임으로 다음 높이를 구한다
function simulate() {
for (let y = 1; y < GH - 1; y += 1) {
for (let x = 1; x < GW - 1; x += 1) {
const i = y * GW + x;
const lap = h[i - 1] + h[i + 1] + h[i - GW] + h[i + GW] - 4 * h[i];
hn[i] = (2 * h[i] - hp[i] + WAVE_C * lap) * DAMPING;
}
}
const old = hp;
hp = h;
h = hn;
hn = old;
}
function randomDrop() {
drop(14 + rnd() * (GW - 28), 14 + rnd() * (GH - 28), DROP_AMP);
}
const scene = {
step() {
t += 1;
if (t % DROP_EVERY === 1) {
randomDrop();
}
if (inp.idle < IDLE_TICKS && t - lastDrop > 9 && inp.idle < 3) {
drop(inp.x * GW / W, inp.y * GH / H, DROP_AMP * 0.6);
lastDrop = t;
}
for (let s = 0; s < SUBSTEPS; s += 1) {
simulate();
}
},
draw(ctx) {
const q = LEVELS - 1;
for (let y = 0; y < GH; y += 1) {
for (let x = 0; x < GW; x += 1) {
const i = y * GW + x;
const tone = clamp(0.5 + h[i] * TONE_GAIN, 0, 1);
const thr = matrix[(y & 7) * 8 + (x & 7)];
const k = clamp(Math.floor(tone * q + thr), 0, q);
buf.px[i] = pal[k];
}
}
flush(ctx, buf);
},
label() {
return inp.idle < 40 ? TXT_DROP : TXT_RAIN;
},
tap() {
drop(inp.x * GW / W, inp.y * GH / H, DROP_AMP * 1.2);
}
};
const prime = reduce ? 160 : 70;
for (let i = 0; i < prime; i += 1) {
scene.step();
}
return scene;
}
start(document.getElementById('scRoot'), document.getElementById('scCanvas'), document.getElementById('scStatus'), document.getElementById('scBtn'), makeScene);
})();import { useEffect, useRef } from "react";
import styles from "./DtDitheredRipplePond.module.scss";
const W = 480;
const H = 300;
const PI2 = Math.PI * 2;
const FIXED_DT = 16;
const REDUCE_STEP_MS = 900;
const KEY_STEP = 14;
const IDLE_TICKS = 150;
const BTN_PAUSE = '멈춤';
const BTN_PLAY = '재생';
const BTN_NEXT = '다음 장면';
// 점을 찍는 작은 격자 — 화면에는 3배로 확대해 올린다
const GW = 160;
const GH = 100;
type RGB = [number, number, number];
interface Input { x: number; y: number; idle: number; }
interface Scene {
step(): void;
draw(ctx: CanvasRenderingContext2D): void;
label(): string;
tap(): void;
}
type Maker = (inp: Input, reduce: boolean) => Scene;
interface Buf {
off: HTMLCanvasElement;
octx: CanvasRenderingContext2D;
img: ImageData;
px: Uint32Array;
}
function clamp(v: number, lo: number, hi: number): number { return v < lo ? lo : (v > hi ? hi : v); }
function lerp(a: number, b: number, k: number): number { return a + (b - a) * k; }
function smooth(x: number): number { const c = clamp(x, 0, 1); return c * c * (3 - 2 * c); }
function frac(x: number): number { return x - Math.floor(x); }
// 시드 고정 난수 — 같은 시드면 언제나 같은 수열 (선형 합동 방식)
function lcg(seed: number): () => number {
let s = seed >>> 0;
return function (): number {
s = (Math.imul(s, 1664525) + 1013904223) >>> 0;
return s / 4294967296;
};
}
// 좌표 두 개와 시드로 0 이상 1 미만의 값을 만드는 정수 해시 (난수 함수 없이도 같은 좌표는 늘 같은 값)
function hash2(x: number, y: number, seed: number): number {
let h = (Math.imul(x | 0, 374761393) + Math.imul(y | 0, 668265263) + Math.imul(seed | 0, 1442695041)) | 0;
h = Math.imul(h ^ (h >>> 13), 1274126177);
h ^= h >>> 16;
return (h >>> 0) / 4294967296;
}
// 격자 네 점의 해시를 smooth 로 이어 붙인 값 노이즈
function vnoise(x: number, y: number, seed: number): number {
const xi = Math.floor(x);
const yi = Math.floor(y);
const fx = smooth(x - xi);
const fy = smooth(y - yi);
const a = lerp(hash2(xi, yi, seed), hash2(xi + 1, yi, seed), fx);
const b = lerp(hash2(xi, yi + 1, seed), hash2(xi + 1, yi + 1, seed), fx);
return lerp(a, b, fy);
}
// 베이어 임계 행렬 — n 은 2 의 거듭제곱. 값은 0 초과 1 미만으로 맞춘다
function makeBayer(n: number): Float32Array {
let size = 2;
let m: number[] = [0, 2, 3, 1];
const quad = [0, 2, 3, 1];
while (size < n) {
const s2 = size * 2;
const next: number[] = [];
for (let y = 0; y < s2; y += 1) {
for (let x = 0; x < s2; x += 1) {
const q = (y >= size ? 2 : 0) + (x >= size ? 1 : 0);
next.push(4 * m[(y % size) * size + (x % size)] + quad[q]);
}
}
m = next;
size = s2;
}
const out = new Float32Array(n * n);
for (let i = 0; i < out.length; i += 1) {
out[i] = (m[i] + 0.5) / (n * n);
}
return out;
}
// 색 하나를 캔버스 픽셀 한 개(리틀 엔디언 RGBA)로 묶는다
function pack(c: RGB): number {
return ((255 << 24) | (Math.round(c[2]) << 16) | (Math.round(c[1]) << 8) | Math.round(c[0])) >>> 0;
}
function mixPack(a: RGB, b: RGB, k: number): number {
return pack([lerp(a[0], b[0], k), lerp(a[1], b[1], k), lerp(a[2], b[2], k)]);
}
function makeBuf(): Buf {
const off = document.createElement('canvas');
off.width = GW;
off.height = GH;
const octx = off.getContext('2d');
if (!octx) {
throw new Error('2d context unavailable');
}
const img = octx.createImageData(GW, GH);
return { off: off, octx: octx, img: img, px: new Uint32Array(img.data.buffer) };
}
// 작은 격자를 큰 캔버스에 보간 없이 확대해 올린다
function flush(ctx: CanvasRenderingContext2D, b: Buf): void {
b.octx.putImageData(b.img, 0, 0);
ctx.imageSmoothingEnabled = false;
ctx.drawImage(b.off, 0, 0, W, H);
}
function start(root: HTMLElement, canvas: HTMLCanvasElement, statusEl: HTMLElement, btnEl: HTMLButtonElement, make: Maker): () => void {
const ctx0 = canvas.getContext('2d');
if (!ctx0) {
return function (): void { return; };
}
const ctx: CanvasRenderingContext2D = ctx0;
const dpr = Math.min(window.devicePixelRatio || 1, 2);
canvas.width = Math.round(W * dpr);
canvas.height = Math.round(H * dpr);
ctx.setTransform(dpr, 0, 0, dpr, 0, 0);
const reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
const inp: Input = { x: W / 2, y: H / 2, idle: 99999 };
const scene = make(inp, reduce);
let paused = false;
let rafId = 0;
let lastTs = -1;
let accMs = 0;
let lastLabel = '';
const cleaners: Array<() => void> = [];
function listen(target: EventTarget, type: string, fn: (e: Event) => void): void {
target.addEventListener(type, fn);
cleaners.push(function (): void { target.removeEventListener(type, fn); });
}
function show(): void {
scene.draw(ctx);
const t = scene.label();
if (t !== lastLabel) {
lastLabel = t;
statusEl.textContent = t;
}
}
function advance(ms: number): void {
const n = Math.round(ms / FIXED_DT);
for (let i = 0; i < n; i += 1) {
inp.idle += 1;
scene.step();
}
}
function refresh(): void {
if (reduce) {
advance(FIXED_DT * 6);
show();
}
}
function toLocal(e: PointerEvent): void {
const r = canvas.getBoundingClientRect();
inp.x = clamp((e.clientX - r.left) * W / r.width, 0, W);
inp.y = clamp((e.clientY - r.top) * H / r.height, 0, H);
inp.idle = 0;
}
function tick(ts: number): void {
if (lastTs < 0) {
lastTs = ts;
}
const frameDt = Math.min(ts - lastTs, 160);
lastTs = ts;
if (!paused) {
accMs += frameDt;
while (accMs >= FIXED_DT) {
inp.idle += 1;
scene.step();
accMs -= FIXED_DT;
}
show();
}
rafId = requestAnimationFrame(tick);
}
btnEl.textContent = reduce ? BTN_NEXT : BTN_PAUSE;
if (reduce) {
root.classList.remove('is-demo');
advance(1400);
show();
}
listen(btnEl, 'click', function (): void {
if (reduce) {
advance(REDUCE_STEP_MS);
show();
return;
}
paused = !paused;
if (paused) {
root.classList.remove('is-demo');
} else {
root.classList.add('is-demo');
}
btnEl.textContent = paused ? BTN_PLAY : BTN_PAUSE;
});
listen(canvas, 'pointermove', function (e: Event): void {
toLocal(e as PointerEvent);
refresh();
});
listen(canvas, 'pointerdown', function (e: Event): void {
toLocal(e as PointerEvent);
scene.tap();
refresh();
});
listen(canvas, 'keydown', function (e: Event): void {
const k = (e as KeyboardEvent).key;
let dx = 0;
let dy = 0;
if (k === 'Enter' || k === ' ') {
e.preventDefault();
scene.tap();
refresh();
return;
}
if (k === 'ArrowLeft') { dx = -KEY_STEP; }
else if (k === 'ArrowRight') { dx = KEY_STEP; }
else if (k === 'ArrowUp') { dy = -KEY_STEP; }
else if (k === 'ArrowDown') { dy = KEY_STEP; }
else { return; }
e.preventDefault();
inp.x = clamp(inp.x + dx, 0, W);
inp.y = clamp(inp.y + dy, 0, H);
inp.idle = 0;
refresh();
});
if (!reduce) {
rafId = requestAnimationFrame(tick);
}
return function (): void {
cancelAnimationFrame(rafId);
for (let i = 0; i < cleaners.length; i += 1) {
cleaners[i]();
}
};
}
const DAMPING = 0.985;
const WAVE_C = 0.4;
const LEVELS = 4;
const DROP_EVERY = 42;
const SUBSTEPS = 2;
const DROP_R = 3.2;
const DROP_AMP = 2.2;
const TONE_GAIN = 0.9;
const PALETTE_05: RGB[] = [[42, 58, 99], [90, 127, 181], [159, 201, 234], [232, 246, 255]];
const TXT_RAIN = '빗방울이 떨어진다 — 물결을 네 단계 명암으로 찍는다';
const TXT_DROP = '포인터가 물방울을 떨어뜨린다';
function makeScene(inp: Input, reduce: boolean): Scene {
const buf = makeBuf();
const matrix = makeBayer(8);
const pal = PALETTE_05.map(pack);
const rnd = lcg(453505);
let h = new Float32Array(GW * GH);
let hp = new Float32Array(GW * GH);
let hn = new Float32Array(GW * GH);
let t = 0;
let lastDrop = 0;
function drop(cx: number, cy: number, amp: number): void {
const r = Math.ceil(DROP_R * 2);
for (let y = Math.max(1, Math.floor(cy) - r); y < Math.min(GH - 1, Math.floor(cy) + r + 1); y += 1) {
for (let x = Math.max(1, Math.floor(cx) - r); x < Math.min(GW - 1, Math.floor(cx) + r + 1); x += 1) {
const d2 = (x - cx) * (x - cx) + (y - cy) * (y - cy);
h[y * GW + x] += amp * Math.exp(-d2 / (DROP_R * DROP_R));
}
}
}
// 파동 방정식 한 걸음 — 이웃 합과 이전 프레임으로 다음 높이를 구한다
function simulate(): void {
for (let y = 1; y < GH - 1; y += 1) {
for (let x = 1; x < GW - 1; x += 1) {
const i = y * GW + x;
const lap = h[i - 1] + h[i + 1] + h[i - GW] + h[i + GW] - 4 * h[i];
hn[i] = (2 * h[i] - hp[i] + WAVE_C * lap) * DAMPING;
}
}
const old = hp;
hp = h;
h = hn;
hn = old;
}
function randomDrop(): void {
drop(14 + rnd() * (GW - 28), 14 + rnd() * (GH - 28), DROP_AMP);
}
const scene: Scene = {
step(): void {
t += 1;
if (t % DROP_EVERY === 1) {
randomDrop();
}
if (inp.idle < IDLE_TICKS && t - lastDrop > 9 && inp.idle < 3) {
drop(inp.x * GW / W, inp.y * GH / H, DROP_AMP * 0.6);
lastDrop = t;
}
for (let s = 0; s < SUBSTEPS; s += 1) {
simulate();
}
},
draw(ctx: CanvasRenderingContext2D): void {
const q = LEVELS - 1;
for (let y = 0; y < GH; y += 1) {
for (let x = 0; x < GW; x += 1) {
const i = y * GW + x;
const tone = clamp(0.5 + h[i] * TONE_GAIN, 0, 1);
const thr = matrix[(y & 7) * 8 + (x & 7)];
const k = clamp(Math.floor(tone * q + thr), 0, q);
buf.px[i] = pal[k];
}
}
flush(ctx, buf);
},
label(): string {
return inp.idle < 40 ? TXT_DROP : TXT_RAIN;
},
tap(): void {
drop(inp.x * GW / W, inp.y * GH / H, DROP_AMP * 1.2);
}
};
const prime = reduce ? 160 : 70;
for (let i = 0; i < prime; i += 1) {
scene.step();
}
return scene;
}
export default function DtDitheredRipplePond() {
const rootRef = useRef<HTMLDivElement | null>(null);
const canvasRef = useRef<HTMLCanvasElement | null>(null);
const statusRef = useRef<HTMLParagraphElement | null>(null);
const btnRef = useRef<HTMLButtonElement | null>(null);
useEffect(() => {
const root = rootRef.current;
const canvas = canvasRef.current;
const statusEl = statusRef.current;
const btnEl = btnRef.current;
if (!root || !canvas || !statusEl || !btnEl) return;
return start(root, canvas, statusEl, btnEl, makeScene);
}, []);
return (
<main className={styles.stage}>
<div className={`${styles.sc} is-demo`} ref={rootRef}>
<canvas className={styles.sc__canvas} ref={canvasRef} width={480} height={300} tabIndex={0} aria-label="파동 방정식으로 퍼지는 물결을 네 단계 명암으로 찍는 디더 연못" />
<p className={styles.sc__status} ref={statusRef} aria-live="polite">빗방울이 떨어진다 — 물결을 네 단계 명암으로 찍는다</p>
<button className={styles.sc__btn} ref={btnRef} type="button">멈춤</button>
<p className={styles.sc__caption}>파동 방정식으로 퍼지는 물결을 네 단계 명암으로 찍는 디더 연못</p>
</div>
</main>
);
}05 A Dithered Pond Where Wave-Equation Ripples Are Stamped in Four Tones — Measured area 62.954% · moving frames 23/23Original by GODRICH · SCSS and React ship in the zip · CSS Dither: 9 Scenes Drawn by Threshold Math
The post this demo lives in
CSS Dither: 9 Scenes Drawn by Threshold MathA css dither throws away every color but two, so why does the gradient look smoother? Scene 01's threshold matrix and sc See all demos in this post
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