09A Gravity Lens That Bends Starlight into a Ring Near a Black Hole
A central mass pushes each star's position by an amount inverse to radius squared, gathering the light into an Einstein-ring shape.
Best forHero focal scenes
LENS_MASSRING_RADIUSFALLOFFSOFTEN
<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 Gravity Lens That Bends Starlight into a Ring Near a Black Hole"></canvas>
<p class="sc__status" id="scStatus" aria-live="polite">Lens mass — the ring gathers starlight</p>
<button class="sc__btn" id="scBtn" type="button">Pause</button>
<p class="sc__caption">A Gravity Lens That Bends Starlight into a Ring Near a Black Hole</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;
}
.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;
}
.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';
const BG = [14, 12, 32];
const STAR_RGBS = [[226, 238, 255], [255, 222, 196], [208, 196, 255], [196, 240, 228], [255, 206, 226]];
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 rgba(c, a) {
return 'rgba(' + Math.round(c[0]) + ',' + Math.round(c[1]) + ',' + Math.round(c[2]) + ',' + clamp(a, 0, 1).toFixed(3) + ')';
}
function mix(a, b, k) {
return [lerp(a[0], b[0], k), lerp(a[1], b[1], k), lerp(a[2], b[2], k)];
}
// 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;
};
}
function glow(ctx, x, y, r, c, a) {
const g = ctx.createRadialGradient(x, y, 0, x, y, r);
g.addColorStop(0, rgba(c, a));
g.addColorStop(1, rgba(c, 0));
ctx.fillStyle = g;
ctx.fillRect(x - r, y - r, r * 2, r * 2);
}
function paintBg(ctx, alpha) {
ctx.fillStyle = rgba(BG, alpha);
ctx.fillRect(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 LENS_MASS = 2600;
const RING_RADIUS = Math.sqrt(LENS_MASS);
const FALLOFF = 1.1;
const SOFTEN = 5;
const FIELD_STARS = 260;
const GALAXY_STARS = 70;
const BOOST_TICKS = 80;
const BOOST_GAIN = 1.9;
const TXT_RING = 'Lens mass — the ring gathers starlight';
const TXT_HEAVY = 'Mass increased — the ring grows';
function makeScene(inp, reduce) {
const rnd = lcg(450909);
const field = [];
for (let i = 0; i < FIELD_STARS; i += 1) {
field.push({ x: rnd() * W, y: rnd() * H, r: 0.7 + 1.3 * rnd() * rnd(), c: STAR_RGBS[Math.floor(rnd() * STAR_RGBS.length)] });
}
// 렌즈 바로 뒤의 작은 은하 — 상대 위치가 0 에 가까워 고리를 만든다
const galaxy = [];
for (let i = 0; i < GALAXY_STARS; i += 1) {
const a = rnd() * PI2;
const rr = 14 * Math.sqrt(rnd());
galaxy.push({ x: Math.cos(a) * rr, y: Math.sin(a) * rr, r: 0.9 + 0.8 * rnd(), c: STAR_RGBS[i % 2 === 0 ? 1 : 4] });
}
let cx = W / 2;
let cy = H / 2;
let t = 0;
let boost = 0;
function mass() {
return LENS_MASS * (1 + (BOOST_GAIN - 1) * smooth(boost / BOOST_TICKS));
}
// 점질량 렌즈: 원천이 렌즈 중심에서 b 만큼 떨어져 있으면 상 두 개가 b 방향의 +th 와 반대쪽 th2 에 맺힌다
function image(ctx, bx, by, r, c, m, alpha) {
const b = Math.hypot(bx, by);
const bs = Math.sqrt(b * b + SOFTEN * SOFTEN);
const root = Math.sqrt(bs * bs + 4 * m);
const thP = (bs + root) / 2;
const thM = (root - bs) / 2;
const u = bs / Math.sqrt(m);
const mag = (u * u + 2) / (2 * u * Math.sqrt(u * u + 4));
const muP = clamp(mag + 0.5, 1, 9);
const muM = clamp(mag - 0.5, 0, 9);
const ux = b > 0.001 ? bx / b : 1;
const uy = b > 0.001 ? by / b : 0;
const ang = Math.atan2(uy, ux) + Math.PI / 2;
const stretchP = clamp(thP / bs, 1, 6);
ctx.fillStyle = rgba(c, alpha * clamp(Math.pow(muP, FALLOFF) * 0.8, 0.3, 1));
ctx.beginPath();
ctx.ellipse(cx + ux * thP, cy + uy * thP, r * stretchP, r * 0.8, ang, 0, PI2);
ctx.fill();
if (muM > 0.04) {
const stretchM = clamp(thM / bs, 0.4, 6);
ctx.fillStyle = rgba(c, alpha * clamp(Math.pow(muM, FALLOFF) * 0.8, 0, 0.9));
ctx.beginPath();
ctx.ellipse(cx - ux * thM, cy - uy * thM, r * Math.max(stretchM, 0.8), r * 0.7, ang, 0, PI2);
ctx.fill();
}
}
const scene = {
step() {
t += 1;
if (boost > 0) {
boost -= 1;
}
let tx = W / 2 + Math.sin(t * 0.012) * 110;
let ty = H / 2 + Math.sin(t * 0.017) * 50;
if (inp.idle < IDLE_TICKS) {
tx = inp.x;
ty = inp.y;
}
cx = lerp(cx, tx, 0.1);
cy = lerp(cy, ty, 0.1);
for (let i = 0; i < field.length; i += 1) {
field[i].x -= 0.7;
if (field[i].x < -8) {
field[i].x += W + 16;
}
}
},
draw(ctx) {
paintBg(ctx, 1);
const m = mass();
for (let i = 0; i < field.length; i += 1) {
const s = field[i];
image(ctx, s.x - cx, s.y - cy, s.r, s.c, m, 0.9);
}
const gx = Math.sin(t * 0.02) * 7;
const gy = Math.cos(t * 0.027) * 5;
for (let i = 0; i < galaxy.length; i += 1) {
const s = galaxy[i];
image(ctx, s.x + gx, s.y + gy, s.r, s.c, m, 0.8);
}
const ring = Math.sqrt(m);
ctx.strokeStyle = rgba([208, 196, 255], 0.14);
ctx.lineWidth = 1;
ctx.beginPath();
ctx.arc(cx, cy, ring, 0, PI2);
ctx.stroke();
glow(ctx, cx, cy, ring * 1.1, [186, 150, 255], 0.12);
const hole = ctx.createRadialGradient(cx, cy, 0, cx, cy, RING_RADIUS * 0.3);
hole.addColorStop(0, rgba(BG, 1));
hole.addColorStop(0.7, rgba(BG, 1));
hole.addColorStop(1, rgba(BG, 0));
ctx.fillStyle = hole;
ctx.fillRect(cx - RING_RADIUS, cy - RING_RADIUS, RING_RADIUS * 2, RING_RADIUS * 2);
},
label() {
return boost > 0 ? TXT_HEAVY : TXT_RING;
},
tap() {
boost = BOOST_TICKS;
}
};
if (reduce) {
for (let i = 0; i < 40; 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 "./SfGravityLensField.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';
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;
const BG: RGB = [14, 12, 32];
const STAR_RGBS: RGB[] = [[226, 238, 255], [255, 222, 196], [208, 196, 255], [196, 240, 228], [255, 206, 226]];
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 rgba(c: RGB, a: number): string {
return 'rgba(' + Math.round(c[0]) + ',' + Math.round(c[1]) + ',' + Math.round(c[2]) + ',' + clamp(a, 0, 1).toFixed(3) + ')';
}
function mix(a: RGB, b: RGB, k: number): RGB {
return [lerp(a[0], b[0], k), lerp(a[1], b[1], k), lerp(a[2], b[2], k)];
}
// 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;
};
}
function glow(ctx: CanvasRenderingContext2D, x: number, y: number, r: number, c: RGB, a: number): void {
const g = ctx.createRadialGradient(x, y, 0, x, y, r);
g.addColorStop(0, rgba(c, a));
g.addColorStop(1, rgba(c, 0));
ctx.fillStyle = g;
ctx.fillRect(x - r, y - r, r * 2, r * 2);
}
function paintBg(ctx: CanvasRenderingContext2D, alpha: number): void {
ctx.fillStyle = rgba(BG, alpha);
ctx.fillRect(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 LENS_MASS = 2600;
const RING_RADIUS = Math.sqrt(LENS_MASS);
const FALLOFF = 1.1;
const SOFTEN = 5;
const FIELD_STARS = 260;
const GALAXY_STARS = 70;
const BOOST_TICKS = 80;
const BOOST_GAIN = 1.9;
const TXT_RING = '렌즈 질량 — 고리가 별빛을 모은다';
const TXT_HEAVY = '질량 증가 — 고리가 커진다';
interface Src { x: number; y: number; r: number; c: RGB; }
function makeScene(inp: Input, reduce: boolean): Scene {
const rnd = lcg(450909);
const field: Src[] = [];
for (let i = 0; i < FIELD_STARS; i += 1) {
field.push({ x: rnd() * W, y: rnd() * H, r: 0.7 + 1.3 * rnd() * rnd(), c: STAR_RGBS[Math.floor(rnd() * STAR_RGBS.length)] });
}
// 렌즈 바로 뒤의 작은 은하 — 상대 위치가 0 에 가까워 고리를 만든다
const galaxy: Src[] = [];
for (let i = 0; i < GALAXY_STARS; i += 1) {
const a = rnd() * PI2;
const rr = 14 * Math.sqrt(rnd());
galaxy.push({ x: Math.cos(a) * rr, y: Math.sin(a) * rr, r: 0.9 + 0.8 * rnd(), c: STAR_RGBS[i % 2 === 0 ? 1 : 4] });
}
let cx = W / 2;
let cy = H / 2;
let t = 0;
let boost = 0;
function mass(): number {
return LENS_MASS * (1 + (BOOST_GAIN - 1) * smooth(boost / BOOST_TICKS));
}
// 점질량 렌즈: 원천이 렌즈 중심에서 b 만큼 떨어져 있으면 상 두 개가 b 방향의 +th 와 반대쪽 th2 에 맺힌다
function image(ctx: CanvasRenderingContext2D, bx: number, by: number, r: number, c: RGB, m: number, alpha: number): void {
const b = Math.hypot(bx, by);
const bs = Math.sqrt(b * b + SOFTEN * SOFTEN);
const root = Math.sqrt(bs * bs + 4 * m);
const thP = (bs + root) / 2;
const thM = (root - bs) / 2;
const u = bs / Math.sqrt(m);
const mag = (u * u + 2) / (2 * u * Math.sqrt(u * u + 4));
const muP = clamp(mag + 0.5, 1, 9);
const muM = clamp(mag - 0.5, 0, 9);
const ux = b > 0.001 ? bx / b : 1;
const uy = b > 0.001 ? by / b : 0;
const ang = Math.atan2(uy, ux) + Math.PI / 2;
const stretchP = clamp(thP / bs, 1, 6);
ctx.fillStyle = rgba(c, alpha * clamp(Math.pow(muP, FALLOFF) * 0.8, 0.3, 1));
ctx.beginPath();
ctx.ellipse(cx + ux * thP, cy + uy * thP, r * stretchP, r * 0.8, ang, 0, PI2);
ctx.fill();
if (muM > 0.04) {
const stretchM = clamp(thM / bs, 0.4, 6);
ctx.fillStyle = rgba(c, alpha * clamp(Math.pow(muM, FALLOFF) * 0.8, 0, 0.9));
ctx.beginPath();
ctx.ellipse(cx - ux * thM, cy - uy * thM, r * Math.max(stretchM, 0.8), r * 0.7, ang, 0, PI2);
ctx.fill();
}
}
const scene: Scene = {
step(): void {
t += 1;
if (boost > 0) {
boost -= 1;
}
let tx = W / 2 + Math.sin(t * 0.012) * 110;
let ty = H / 2 + Math.sin(t * 0.017) * 50;
if (inp.idle < IDLE_TICKS) {
tx = inp.x;
ty = inp.y;
}
cx = lerp(cx, tx, 0.1);
cy = lerp(cy, ty, 0.1);
for (let i = 0; i < field.length; i += 1) {
field[i].x -= 0.7;
if (field[i].x < -8) {
field[i].x += W + 16;
}
}
},
draw(ctx: CanvasRenderingContext2D): void {
paintBg(ctx, 1);
const m = mass();
for (let i = 0; i < field.length; i += 1) {
const s = field[i];
image(ctx, s.x - cx, s.y - cy, s.r, s.c, m, 0.9);
}
const gx = Math.sin(t * 0.02) * 7;
const gy = Math.cos(t * 0.027) * 5;
for (let i = 0; i < galaxy.length; i += 1) {
const s = galaxy[i];
image(ctx, s.x + gx, s.y + gy, s.r, s.c, m, 0.8);
}
const ring = Math.sqrt(m);
ctx.strokeStyle = rgba([208, 196, 255], 0.14);
ctx.lineWidth = 1;
ctx.beginPath();
ctx.arc(cx, cy, ring, 0, PI2);
ctx.stroke();
glow(ctx, cx, cy, ring * 1.1, [186, 150, 255], 0.12);
const hole = ctx.createRadialGradient(cx, cy, 0, cx, cy, RING_RADIUS * 0.3);
hole.addColorStop(0, rgba(BG, 1));
hole.addColorStop(0.7, rgba(BG, 1));
hole.addColorStop(1, rgba(BG, 0));
ctx.fillStyle = hole;
ctx.fillRect(cx - RING_RADIUS, cy - RING_RADIUS, RING_RADIUS * 2, RING_RADIUS * 2);
},
label(): string {
return boost > 0 ? TXT_HEAVY : TXT_RING;
},
tap(): void {
boost = BOOST_TICKS;
}
};
if (reduce) {
for (let i = 0; i < 40; i += 1) {
scene.step();
}
}
return scene;
}
export default function SfGravityLensField() {
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="블랙홀 가까이에서 별빛이 고리로 휘는 중력 렌즈" />
<p className={styles.sc__status} ref={statusRef} aria-live="polite">렌즈 질량 — 고리가 별빛을 모은다</p>
<button className={styles.sc__btn} ref={btnRef} type="button">멈춤</button>
<p className={styles.sc__caption}>블랙홀 가까이에서 별빛이 고리로 휘는 중력 렌즈</p>
</div>
</main>
);
}09 A Gravity Lens That Bends Starlight into a Ring Near a Black Hole — Measured area 30.934% · moving frames 23/23Original by GODRICH · SCSS and React ship in the zip · CSS Starfield: 9 Backgrounds Stars Fly Through
The post this demo lives in
CSS Starfield: 9 Backgrounds Stars Fly ThroughA css starfield of a few CSS-animated dots has no depth and a flat constant speed — scenes 01, 02 and 05 solve it with p See all demos in this post
