# Arched Stained Glass Window WebGL Background That Pours Coloured Light Across a Stone Floor as the Sun Moves > WebGL background where leaded windows cast coloured light across a stone floor, sliding as the sun moves. Copy the React code or the HTML version free. A shadcn/ui block from the [@weinc](https://we.inc/components?utm_source=shadcn.exchange) registry, listed on [shadcn.exchange](https://shadcn.exchange/r/weinc/arched-stained-glass-window-webgl-background-that-pours-coloured-light-across-a-stone-floor-as-the-sun-moves). - Page, with a live preview: https://shadcn.exchange/r/weinc/arched-stained-glass-window-webgl-background-that-pours-coloured-light-across-a-stone-floor-as-the-sun-moves - Screenshot: https://shadcn.exchange/shot/weinc/arched-stained-glass-window-webgl-background-that-pours-coloured-light-across-a-stone-floor-as-the-sun-moves/light.png - Registry item: https://we.inc/r/arched-stained-glass-window-webgl-background-that-pours-coloured-light-across-a-stone-floor-as-the-sun-moves.json - Listed: 2026-10-28, source last changed 2026-10-28 ## Install ```bash npx shadcn@latest add https://shadcn.exchange/r/weinc/arched-stained-glass-window-webgl-background-that-pours-coloured-light-across-a-stone-floor-as-the-sun-moves.json ``` Run it in a project that has shadcn/ui set up. It adds the files below and installs what they depend on. ## Dependencies - npm packages: `framer-motion` ## Files ### `components/we-inc/arched-stained-glass-window-webgl-background-that-pours-coloured-light-across-a-stone-floor-as-the-sun-moves.tsx` ```tsx import { useEffect, useRef, useState } from "react"; import type { PointerEvent as ReactPointerEvent } from "react"; import { useReducedMotion } from "framer-motion"; /** The glass. Change these and the light on the floor changes with them. */ const glass = { sky: ["#12308f", "#1f5fcf", "#2f8fd8", "#8cc8ea", "#432a94", "#1a4cb8"], sun: ["#ffcf2e", "#f47c12", "#cf1b2b"], rays: ["#f6a21a", "#ffd866"], hills: ["#6a2f98", "#0f8a6c", "#5fb233", "#0b5c36"], /** How many wedges of sky fan out from the sun. */ wedges: 20, }; const room = { /** Limestone floor and plaster wall, as linear red, green, blue from 0 to 1. */ floor: [0.62, 0.55, 0.46], wall: [0.8, 0.73, 0.64], /** How thick the air is. 0 removes the shafts of light, 0.1 is a dusty chapel. */ haze: 0.085, /** The hours the slider covers, and where the day starts when the page loads. */ from: 8, to: 18, start: 0.24, quality: 0.9, maxPixels: 760000, }; // The window opening in metres: the texture covers a slightly larger box so its edges are dark. const BOX = { x: -0.9, y: 0.9, w: 1.8, h: 3.375 }; const TEX_W = 512; const TEX_H = 960; /** Paints the leaded window: a sun behind hills with a fan of sky panes, drawn back to front. */ function paintGlass() { const cv = document.createElement("canvas"); cv.width = TEX_W; cv.height = TEX_H; const c = cv.getContext("2d")!; const k = TEX_W / BOX.w; const X = (x: number) => (x - BOX.x) * k; const Y = (y: number) => TEX_H - (y - BOX.y) * k; c.fillStyle = "#000"; c.fillRect(0, 0, TEX_W, TEX_H); const arch = () => { c.beginPath(); c.moveTo(X(-0.8), Y(1.0)); c.lineTo(X(-0.8), Y(3.4)); c.arc(X(0), Y(3.4), 0.8 * k, Math.PI, 0); c.lineTo(X(0.8), Y(1.0)); c.closePath(); }; c.save(); arch(); c.clip(); c.lineJoin = "round"; c.strokeStyle = "#060505"; c.lineWidth = 7; let seed = 5; const pane = (fill: string) => { c.fillStyle = fill; c.fill(); // No two pieces come off the sheet the same: each is a touch lighter or darker. seed = (seed * 16807) % 2147483647; const tone = seed / 2147483647 - 0.5; c.fillStyle = tone > 0 ? `rgba(255,255,255,${tone * 0.34})` : `rgba(0,0,20,${-tone * 0.5})`; c.fill(); c.stroke(); }; const sx = X(0.06); const sy = Y(2.08); // Sky: rings of wedges, the widest ring first so nearer rings cover it. const rings = [3.2, 2.2, 1.72, 1.3, 0.94]; const step = (Math.PI * 2) / glass.wedges; rings.forEach((radius, ri) => { for (let i = 0; i < glass.wedges; i++) { const a0 = i * step + ri * step * 0.5 + 0.11; c.beginPath(); c.moveTo(sx, sy); c.arc(sx, sy, radius * k, a0, a0 + step); c.closePath(); pane(glass.sky[(i * 2 + ri * 3 + (i % 4 === 0 ? 1 : 0)) % glass.sky.length]); } }); // The sun's rays, then the sun itself in three rings. for (let i = 0; i < glass.wedges * 2; i++) { c.beginPath(); c.moveTo(sx, sy); c.arc(sx, sy, 0.66 * k, (i * step) / 2, ((i + 1) * step) / 2); c.closePath(); pane(glass.rays[i % 2]); } [0.46, 0.33, 0.2].forEach((radius, i) => { c.beginPath(); c.arc(sx, sy, radius * k, 0, Math.PI * 2); pane(glass.sun[2 - i]); }); // Four ranges of hills, far to near, each cut into panes by a few slanting leads. const ranges = [ { base: 2.02, rise: 0.13, wave: 3.1, shift: 0.4 }, { base: 1.74, rise: 0.11, wave: 4.2, shift: 2.1 }, { base: 1.47, rise: 0.09, wave: 3.4, shift: 4.0 }, { base: 1.2, rise: 0.07, wave: 5.0, shift: 1.2 }, ]; ranges.forEach((r, i) => { const top = (x: number) => r.base + r.rise * Math.sin(x * r.wave + r.shift); const cuts = [-0.9, -0.42 + i * 0.07, 0.02 - i * 0.09, 0.45 + i * 0.05, 0.9]; for (let j = 0; j < cuts.length - 1; j++) { c.beginPath(); for (let s = 0; s <= 12; s++) { const x = cuts[j] + ((cuts[j + 1] - cuts[j]) * s) / 12; if (s === 0) c.moveTo(X(x), Y(top(x))); else c.lineTo(X(x), Y(top(x))); } c.lineTo(X(cuts[j + 1] + 0.08), Y(0.8)); c.lineTo(X(cuts[j] + 0.08), Y(0.8)); c.closePath(); c.globalAlpha = 1; pane(glass.hills[i]); // Alternate panes are a shade lighter, as hand-cut glass from different sheets would be. if ((i + j) % 2 === 0) { c.fillStyle = "rgba(255,255,255,0.13)"; c.fill(); c.stroke(); } } }); // Iron saddle bars across the panel, and the heavy lead round the edge. c.lineWidth = 4; for (const y of [1.62, 2.5, 3.38]) { c.beginPath(); c.moveTo(X(-0.9), Y(y)); c.lineTo(X(0.9), Y(y)); c.stroke(); } c.restore(); c.strokeStyle = "#060505"; c.lineWidth = 12; arch(); c.stroke(); return cv; } const VERTEX = `attribute vec2 position; void main(){ gl_Position = vec4(position, 0.0, 1.0); }`; const FRAGMENT = `precision highp float; uniform vec2 uRes; uniform float uZoom; uniform float uPan; uniform vec3 uSun; uniform vec3 uSunCol; uniform vec3 uMean; uniform vec3 uFloor; uniform vec3 uWall; uniform float uHaze; uniform sampler2D uSharp; uniform sampler2D uMid; uniform sampler2D uSoft; const vec2 BMIN = vec2(${BOX.x.toFixed(3)}, ${BOX.y.toFixed(3)}); const vec2 BSIZE = vec2(${BOX.w.toFixed(3)}, ${BOX.h.toFixed(3)}); const float SIDE = -3.6; const float PAIR = 1.3; const vec3 BALL = vec3(-0.02, 0.42, 1.95); const float BALLR = 0.42; float hash(vec2 p){ return fract(sin(dot(p, vec2(127.1, 311.7))) * 43758.5453); } float noise(vec2 p){ vec2 i = floor(p), f = fract(p); vec2 u = f * f * (3.0 - 2.0 * f); return mix(mix(hash(i), hash(i + vec2(1.0, 0.0)), u.x), mix(hash(i + vec2(0.0, 1.0)), hash(i + vec2(1.0, 1.0)), u.x), u.y); } float fbm(vec2 p){ return noise(p) * 0.55 + noise(p * 2.1 + 7.0) * 0.3 + noise(p * 4.3 + 19.0) * 0.15; } // The colour of the glass at a point on the window wall, at a chosen softness from 0 to 2. vec3 glassAt(vec2 xy, float soft){ // Two lancets side by side, the second a mirror image of the first. xy.x = abs(xy.x) - PAIR; vec2 uv = (xy - BMIN) / BSIZE; if (uv.x < -0.3 || uv.x > 1.3 || uv.y < -0.3 || uv.y > 1.3) return vec3(0.0); uv = clamp(uv, 0.0, 1.0); vec3 a = texture2D(uSharp, uv).rgb; vec3 b = texture2D(uMid, uv).rgb; vec3 c = texture2D(uSoft, uv).rgb; vec3 col = soft < 1.0 ? mix(a, b, clamp(soft, 0.0, 1.0)) : mix(b, c, clamp(soft - 1.0, 0.0, 1.0)); return col * col; } // Distance outside the arched opening (negative inside). float archDist(vec2 p){ p.x = abs(abs(p.x) - PAIR); if (p.y > 3.4) return length(p - vec2(0.0, 3.4)) - 0.8; vec2 d = vec2(p.x - 0.8, 1.0 - p.y); return min(max(d.x, d.y), 0.0) + length(max(d, 0.0)); } // Sunlight that has come through the window to reach p, with the stone ball in the way or not. vec3 sunAt(vec3 p, float extraSoft, bool ballShadow){ if (p.z <= 0.001) return vec3(0.0); float u = p.z / uSun.z; vec3 q = p - uSun * u; vec3 g = glassAt(q.xy, clamp(u * 0.24 + extraSoft, 0.12, 2.0)); if (ballShadow) { vec3 oc = BALL - p; float along = dot(oc, -uSun); if (along > 0.0) { float miss = length(oc + uSun * along); float pen = 0.012 + 0.03 * along; g *= smoothstep(BALLR - pen, BALLR + pen, miss); } } return g * uSunCol; } void main(){ vec2 uv = (gl_FragCoord.xy * 2.0 - uRes) / uRes.y * uZoom; vec3 ro = vec3(uPan, 2.8, 6.6); vec3 ta = vec3(uPan, 1.9, 1.0); vec3 fw = normalize(ta - ro); vec3 rt = normalize(cross(fw, vec3(0.0, 1.0, 0.0))); vec3 up = cross(rt, fw); // A little downward shift of the lens, as an architectural camera has, keeps the window upright. vec3 rd = normalize(fw * 1.7 + rt * uv.x + up * (uv.y - 0.2)); vec3 L = -uSun; // What the ray meets first: floor, window wall, side wall or the ball. float t = 1e5; float id = 0.0; if (rd.y < 0.0) { float tf = -ro.y / rd.y; if (tf < t) { t = tf; id = 1.0; } } if (rd.z < 0.0) { float tw = -ro.z / rd.z; if (tw < t) { t = tw; id = 2.0; } } if (rd.x < 0.0) { float ts = (SIDE - ro.x) / rd.x; if (ts < t) { t = ts; id = 3.0; } } vec3 oc = ro - BALL; float bb = dot(oc, rd); float disc = bb * bb - dot(oc, oc) + BALLR * BALLR; if (disc > 0.0) { float tb = -bb - sqrt(disc); if (tb > 0.0 && tb < t) { t = tb; id = 4.0; } } vec3 p = ro + rd * t; // Where the pool of light lies on the floor: it lights the rest of the room from below. float poolReach = 2.4 / -uSun.y; vec3 pool = vec3(uSun.x * poolReach, 0.0, uSun.z * poolReach); vec3 bounceCol = uMean * uSunCol * uFloor; vec3 skylight = vec3(0.05, 0.044, 0.04); vec3 col = vec3(0.0); if (id < 1.5) { // Limestone flags laid in courses, each a slightly different tone, with fine joints. vec2 g = vec2(p.x / 1.3, p.z / 0.86); g.x += floor(g.y) * 0.5; vec2 cell = floor(g); vec2 f = fract(g); float joint = smoothstep(0.0, 0.012, min(min(f.x, 1.0 - f.x) * 1.3, min(f.y, 1.0 - f.y) * 0.86)); vec3 albedo = uFloor * (0.9 + 0.14 * hash(cell)) * (0.84 + 0.3 * fbm(p.xz * 3.0 + cell * 3.0)) * (0.94 + 0.12 * noise(p.xz * 60.0)); albedo = mix(albedo * 0.68, albedo, joint); vec3 direct = sunAt(p, 0.0, true) * max(L.y, 0.0) * 4.4; float under = 1.0 - 0.55 * exp(-dot(p.xz - BALL.xz, p.xz - BALL.xz) * 5.5); float corner = (1.0 - 0.35 * exp(-p.z * 3.2)) * (1.0 - 0.3 * exp(-(p.x - SIDE) * 3.0)); vec3 amb = skylight * 1.25 + bounceCol * 0.16 / (1.0 + dot(p - pool, p - pool) * 0.3); col = albedo * (direct + amb * under * corner); // Worn stone has a soft polish: it mirrors the bright window, more so at a glancing angle. vec3 r = vec3(rd.x, -rd.y, rd.z); if (r.z < 0.0) { vec3 q = p + r * (-p.z / r.z); float fres = 0.03 + 0.6 * pow(1.0 - max(-rd.y, 0.0), 5.0); float rough = 0.75 + 0.5 * fbm(p.xz * 7.0); col += glassAt(q.xy, rough + q.y * 0.12) * fres * 2.0 * (0.6 + 0.4 * joint) * under; } } else if (id < 2.5) { float d = archDist(p.xy); if (d < 0.0) { // The glass itself: streaky, a little seedy, brightest where the sun stands behind it. vec3 g = glassAt(p.xy, 0.0); float streak = 0.74 + 0.5 * fbm(vec2(p.x * 2.2 + p.y * 0.8, p.y * 5.0 - p.x * 2.6)); float seed = smoothstep(0.84, 0.9, noise(p.xy * 70.0)); float toSun = pow(max(dot(rd, L), 0.0), 14.0); col = g * (streak * 0.74 + seed * 0.2) * (0.8 + 0.5 * uSunCol) + g * uSunCol * toSun * 4.0; col += uSunCol * pow(max(dot(rd, L), 0.0), 900.0) * dot(g, vec3(0.4)) * 4.0; } else { // Plaster, with a dressed stone surround and a dark reveal where the wall is cut through. float m = fbm(p.xy * 1.6) * 0.6 + fbm(p.xy * 9.0) * 0.4; vec3 albedo = uWall * (0.88 + 0.2 * m); float surround = 1.0 - smoothstep(0.12, 0.124, d); albedo = mix(albedo, uWall * vec3(1.08, 1.05, 1.0) * (0.92 + 0.16 * noise(p.xy * 26.0)), surround); float groove = smoothstep(0.008, 0.0, abs(d - 0.124)) * 0.35 + smoothstep(0.03, 0.0, d) * 0.8; float lowGlow = 1.0 / (1.0 + dot(p - pool, p - pool) * 0.2); vec3 amb = skylight + bounceCol * 0.5 * lowGlow * (0.4 + 0.6 * smoothstep(3.6, 0.0, p.y)); float corner = (1.0 - 0.3 * exp(-p.y * 2.6)) * (1.0 - 0.34 * exp(-(p.x - SIDE) * 2.4)); col = albedo * amb * corner * (1.0 - groove); // Glare: the bright glass spreads a little light onto the stone round it. col += glassAt(p.xy, 2.0) * uSunCol * 0.5 * albedo * exp(-d * 2.2); } } else if (id < 3.5) { float m = fbm(p.zy * 1.6) * 0.6 + fbm(p.zy * 9.0) * 0.4; vec3 albedo = uWall * (0.88 + 0.2 * m); vec3 direct = sunAt(p, 0.0, true) * max(L.x, 0.0) * 4.4; float lowGlow = 1.0 / (1.0 + dot(p - pool, p - pool) * 0.2); vec3 amb = skylight * 1.1 + bounceCol * 0.45 * lowGlow; float corner = (1.0 - 0.3 * exp(-p.y * 2.6)) * (1.0 - 0.34 * exp(-p.z * 2.4)); col = albedo * (direct + amb * corner); } else { // A ball of pale stone: the pattern wraps round it and its own far side stays in shade. vec3 n = normalize(p - BALL); float speck = fbm(n.xy * 9.0 + n.z * 5.0); vec3 albedo = vec3(0.84, 0.81, 0.76) * (0.92 + 0.12 * speck); vec3 direct = sunAt(p, 0.7, false) * max(dot(n, L), 0.0) * 4.4; vec3 fromFloor = (sunAt(vec3(p.x, 0.0, p.z + 0.2), 1.2, false) * uFloor * 0.9 + bounceCol * 0.2) * (0.5 - 0.5 * n.y); vec3 amb = skylight * (0.75 + 0.5 * n.y) * 1.3; col = albedo * (direct + fromFloor + amb * (0.6 + 0.4 * smoothstep(-1.0, 0.2, n.y))); } // Dust in the air: every shaft carries the colour of the pane it came through. if (uHaze > 0.0) { float far = min(t, 11.0); float jitter = fract(52.9829189 * fract(dot(gl_FragCoord.xy, vec2(0.06711056, 0.00583715)))); vec3 shafts = vec3(0.0); for (int i = 0; i < 16; i++) { vec3 at = ro + rd * ((float(i) + jitter) / 16.0 * far); if (at.z > 0.001) { vec2 back = (at - uSun * (at.z / uSun.z)).xy; back.x = abs(back.x) - PAIR; vec2 quv = (back - BMIN) / BSIZE; if (quv.x > 0.0 && quv.x < 1.0 && quv.y > 0.0 && quv.y < 1.0) { vec3 g = texture2D(uMid, quv).rgb; shafts += g * g; } } } shafts *= uSunCol; float forward = 0.35 + 2.6 * pow(max(dot(rd, L), 0.0), 5.0); col += shafts / 16.0 * far * uHaze * forward; } col *= 1.3; col = (col * (2.51 * col + 0.03)) / (col * (2.43 * col + 0.59) + 0.14); col = pow(clamp(col, 0.0, 1.0), vec3(0.4545)); vec2 v = gl_FragCoord.xy / uRes - 0.5; col *= 1.0 - dot(v, v) * 0.42; col += (fract(52.9829189 * fract(dot(gl_FragCoord.xy + 31.0, vec2(0.06711056, 0.00583715)))) - 0.5) * 0.012; gl_FragColor = vec4(col, 1.0); }`; const mix = (a: number, b: number, t: number) => a + (b - a) * t; /** The sun for a moment of the day (0 morning, 1 evening): its direction into the room and its colour. */ function sunFor(day: number) { const turn = (0.5 - day) * 2.1; const lift = 0.6 + 0.2 * Math.sin(Math.PI * day); const low = 1 - Math.sin(Math.PI * day); return { dir: [Math.sin(turn) * Math.cos(lift), -Math.sin(lift), Math.cos(turn) * Math.cos(lift)], tint: [1.0, mix(0.95, 0.74, low), mix(0.86, 0.5, low)], }; } function clock(day: number) { const hours = room.from + (room.to - room.from) * day; const h = Math.floor(hours); const m = Math.floor(((hours - h) * 60) / 5) * 5; return `${h}:${String(m).padStart(2, "0")}`; } export default function StainedGlassWindow() { const reduce = useReducedMotion(); const stage = useRef(null); const canvas = useRef(null); const [live, setLive] = useState(false); const [day, setDay] = useState(room.start); const [pick, setPick] = useState(room.start); const want = useRef({ day: room.start, touched: -1e9 }); useEffect(() => { const cv = canvas.current; const el = stage.current; const gl = cv?.getContext("webgl", { antialias: false, alpha: false }); if (!cv || !el || !gl) return; // no WebGL: the painted still underneath stays const compile = (type: number, source: string) => { const s = gl.createShader(type)!; gl.shaderSource(s, source); gl.compileShader(s); return s; }; const program = gl.createProgram()!; gl.attachShader(program, compile(gl.VERTEX_SHADER, VERTEX)); gl.attachShader(program, compile(gl.FRAGMENT_SHADER, FRAGMENT)); gl.linkProgram(program); if (!gl.getProgramParameter(program, gl.LINK_STATUS)) return; gl.useProgram(program); gl.bindBuffer(gl.ARRAY_BUFFER, gl.createBuffer()); gl.bufferData(gl.ARRAY_BUFFER, new Float32Array([-1, -1, 3, -1, -1, 3]), gl.STATIC_DRAW); const position = gl.getAttribLocation(program, "position"); gl.enableVertexAttribArray(position); gl.vertexAttribPointer(position, 2, gl.FLOAT, false, 0, 0); const at = (name: string) => gl.getUniformLocation(program, name); const u = { res: at("uRes"), zoom: at("uZoom"), pan: at("uPan"), sun: at("uSun"), sunCol: at("uSunCol") }; // The window is painted once, then kept at three sharpnesses: light blurs as it travels. const sharp = paintGlass(); const shrink = (from: HTMLCanvasElement, w: number, h: number) => { const c = document.createElement("canvas"); c.width = w; c.height = h; const x = c.getContext("2d")!; x.imageSmoothingQuality = "high"; x.drawImage(from, 0, 0, w, h); return c; }; const mid = shrink(shrink(sharp, 256, 480), 112, 210); const soft = shrink(shrink(mid, 56, 105), 26, 49); gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, true); [sharp, mid, soft].forEach((source, i) => { gl.activeTexture(gl.TEXTURE0 + i); gl.bindTexture(gl.TEXTURE_2D, gl.createTexture()); gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, source); gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR); gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR); gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE); gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE); gl.uniform1i(at(["uSharp", "uMid", "uSoft"][i]), i); }); // The average colour of the glass tints the light that bounces round the room. const px = soft.getContext("2d")!.getImageData(0, 0, soft.width, soft.height).data; const sum = [0, 0, 0]; for (let i = 0; i < px.length; i += 4) for (let c = 0; c < 3; c++) sum[c] += (px[i + c] / 255) ** 2; const count = px.length / 4; gl.uniform3f(at("uMean"), (sum[0] / count) * 2.2, (sum[1] / count) * 2.2, (sum[2] / count) * 2.2); gl.uniform3fv(at("uFloor"), room.floor); gl.uniform3fv(at("uWall"), room.wall); gl.uniform1f(at("uHaze"), room.haze); let now = want.current.day; let raf = 0; let visible = true; let before = 0; let time = 0; let shown = clock(now); const draw = () => { const s = sunFor(now); gl.uniform3fv(u.sun, s.dir); gl.uniform3fv(u.sunCol, s.tint); gl.drawArrays(gl.TRIANGLES, 0, 3); }; const resize = () => { const w = cv.clientWidth || 1; const h = cv.clientHeight || 1; const scale = Math.min(Math.min(Math.max(window.devicePixelRatio || 1, 1), 2) * room.quality, Math.sqrt(room.maxPixels / (w * h))); cv.width = Math.max(1, Math.round(w * scale)); cv.height = Math.max(1, Math.round(h * scale)); gl.viewport(0, 0, cv.width, cv.height); gl.uniform2f(u.res, cv.width, cv.height); gl.uniform1f(u.zoom, Math.max(1, 0.82 / (w / h))); // Wide screens stand to one side, so the window sits left and the light falls across the middle. const wide = Math.min(1, Math.max(0, (w / h - 0.9) / 0.7)); gl.uniform1f(u.pan, 0.35 + 1.25 * wide * wide * (3 - 2 * wide)); draw(); setLive(true); }; const loop = (stamp: number) => { raf = requestAnimationFrame(loop); const dt = Math.min((stamp - (before || stamp)) / 1000, 0.05); before = stamp; time += dt; const w = want.current; // Left alone, the afternoon drifts on and comes back. if (!reduce && stamp - w.touched > 3000) w.day = room.start + 0.11 * Math.sin(time * 0.22); now = reduce ? w.day : mix(now, w.day, 1 - Math.exp(-dt * 3)); draw(); const label = clock(now); if (label !== shown) { shown = label; setDay(now); // The slider follows the sun unless a hand is on it. if (stamp > w.touched) setPick(now); } }; const wake = () => { cancelAnimationFrame(raf); raf = 0; before = 0; if (visible && !document.hidden) raf = requestAnimationFrame(loop); }; const ro = new ResizeObserver(resize); ro.observe(el); const io = new IntersectionObserver(([entry]) => { visible = entry.isIntersecting; wake(); }); io.observe(el); document.addEventListener("visibilitychange", wake); resize(); wake(); return () => { cancelAnimationFrame(raf); ro.disconnect(); io.disconnect(); document.removeEventListener("visibilitychange", wake); }; }, [reduce]); /** The pointer carries the sun: left edge is morning, right edge is evening. */ function steer(e: ReactPointerEvent) { if (e.pointerType !== "mouse" && e.type === "pointermove" && e.buttons === 0) return; const r = e.currentTarget.getBoundingClientRect(); want.current = { day: Math.min(1, Math.max(0, ((e.clientX - r.left) / r.width - 0.08) / 0.84)), touched: performance.now() }; } return (
{/* The still version, shown until the first frame is drawn and wherever WebGL is missing. */}
); } ```