# Ray Marched Paper Pop-Up Book Scroll Story Where a Tea Hillside, a Drying Barn and a Tin Unfold from the Spread > Free scroll story in React: a cloth book opens on a table as you scroll and paper hills, a barn and a tin stand up, one per heading. Copy the code. 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/ray-marched-paper-pop-up-book-scroll-story-where-a-tea-hillside-a-drying-barn-and-a-tin-unfold-from-the-spread). - Page, with a live preview: https://shadcn.exchange/r/weinc/ray-marched-paper-pop-up-book-scroll-story-where-a-tea-hillside-a-drying-barn-and-a-tin-unfold-from-the-spread - Screenshot: https://shadcn.exchange/shot/weinc/ray-marched-paper-pop-up-book-scroll-story-where-a-tea-hillside-a-drying-barn-and-a-tin-unfold-from-the-spread/light.png - Registry item: https://we.inc/r/ray-marched-paper-pop-up-book-scroll-story-where-a-tea-hillside-a-drying-barn-and-a-tin-unfold-from-the-spread.json - Listed: 2026-10-28, source last changed 2026-10-28 ## Install ```bash npx shadcn@latest add https://shadcn.exchange/r/weinc/ray-marched-paper-pop-up-book-scroll-story-where-a-tea-hillside-a-drying-barn-and-a-tin-unfold-from-the-spread.json ``` Run it in a project that has shadcn/ui set up. It adds the files below and installs what they depend on. ## Files ### `components/we-inc/ray-marched-paper-pop-up-book-scroll-story-where-a-tea-hillside-a-drying-barn-and-a-tin-unfold-from-the-spread.tsx` ```tsx import { useEffect, useRef, useState } from "react"; // The story. Each beat is one fold of the pop-up: where the page has to reach for it to stand. const beats = [ { fold: "Ridge", title: "Grown on the ridge", body: "Fernmoor leaves are picked by hand on the terraces above the river, only the bud and the top two leaves, before the morning mist has lifted.", at: 0.64 }, { fold: "Barn", title: "Withered in the barn", body: "They rest overnight on slatted racks in the old drying barn and are turned twice by hand, so every leaf softens at the same pace.", at: 0.83 }, { fold: "Tin", title: "Sealed in the tin", body: "Rolled, fired and packed the same week into a lined paper tin, so the cup you pour still tastes of the hillside it came from.", at: 1 }, ]; const BRAND = "Fernmoor Tea"; const STORY = "Spring picking, told in three folds"; const FONT = '"Inter Tight", "Inter", ui-sans-serif, system-ui, -apple-system, "Segoe UI", sans-serif'; const SERIF = '"Iowan Old Style", "Palatino Linotype", Palatino, "Book Antiqua", Georgia, serif'; // When each paper piece stands, as a share of the story (0 closed, 1 fully open). const COVER = [0, 0.3]; const RISE = [[0.3, 0.5], [0.36, 0.56], [0.42, 0.62], [0.64, 0.8], [0.84, 0.98]]; const beatOf = (p: number) => (p < 0.735 ? 0 : p < 0.915 ? 1 : 2); const sm = (a: number, b: number, x: number) => { const t = Math.max(0, Math.min(1, (x - a) / (b - a))); return t * t * (3 - 2 * t); }; const VERT = `ATTR vec2 aPos; void main(){ gl_Position = vec4(aPos, 0.0, 1.0); }`; const TONE = ` vec3 tone(vec3 x){ x *= 0.92; vec3 a = x * (2.51 * x + 0.03); vec3 b = x * (2.43 * x + 0.59) + 0.14; return pow(clamp(a / b, 0.0, 1.0), vec3(1.0 / 2.2)); } `; // A cloth-bound book lying open on a linen table in low afternoon light from the left and behind. // Three cut-paper ridges, a drying barn and a tea tin stand up out of the spread. const SCENE = ` precision highp float; uniform vec2 uRes; uniform vec4 uJit; uniform float uSeed; uniform vec3 uCam; uniform vec3 uTgt; uniform float uFoc; uniform vec2 uShift; uniform float uFocus; uniform float uTh; uniform vec4 uA; uniform float uTin; uniform vec3 uL; uniform sampler2D uTex; uniform float uDirect; const float YT = 0.17; const vec3 SUN = vec3(1.0, 0.86, 0.68); ${TONE} float h21(vec2 p){ vec3 q = fract(vec3(p.xyx) * 0.1031); q += dot(q, q.yzx + 33.33); return fract((q.x + q.y) * q.z); } float n2(vec2 x){ vec2 i = floor(x); vec2 f = fract(x); f = f * f * (3.0 - 2.0 * f); return mix(mix(h21(i), h21(i + vec2(1.0, 0.0)), f.x), mix(h21(i + vec2(0.0, 1.0)), h21(i + vec2(1.0, 1.0)), f.x), f.y); } float sdBox(vec3 p, vec3 b, float r){ vec3 q = abs(p) - b + r; return length(max(q, 0.0)) + min(max(q.x, max(q.y, q.z)), 0.0) - r; } float sdCyl(vec3 p, float r, float h, float rr){ vec2 d = vec2(length(p.xz) - r + rr, abs(p.y) - h + rr); return min(max(d.x, d.y), 0.0) + length(max(d, 0.0)) - rr; } // the page surface sinks into the gutter float topY(float x){ return YT - 0.075 * exp(-abs(x) * 6.0); } // the left half of the book, swung about the spine by uTh, seen in its own (mirrored) frame vec3 toLeft(vec3 p){ vec2 r = vec2(p.x, p.y - YT); float c = cos(uTh), s = sin(uTh); vec2 l = vec2(r.x * c - r.y * s, r.x * s + r.y * c); return vec3(-l.x, l.y + YT, p.z); } vec2 halfBook(vec3 q){ float b = sdBox(q - vec3(1.07, 0.024, 0.0), vec3(1.07, 0.024, 1.52), 0.014); float pg = sdBox(q - vec3(1.04, 0.11, 0.0), vec3(1.0, 0.07, 1.45), 0.008); pg = max(pg, (q.y - topY(q.x)) * 0.9); return b < pg ? vec2(b, 1.0) : vec2(pg, 2.0); } // ---- cut paper ridges, hinged at their foot, lying forward when folded ---- float ridgeH(float X, float i){ float h; if (i < 0.5) h = 0.9 + 0.18 * sin(X * 1.3 + 0.5) + 0.07 * sin(X * 3.7 + 1.0); else if (i < 1.5) h = 0.64 + 0.15 * sin(X * 1.8 + 2.3) + 0.05 * sin(X * 5.3 + 1.0); else { h = 0.4 + 0.11 * sin(X * 2.3 + 4.1); h += 0.028 * sqrt(abs(sin(X * 13.0))); } return h * smoothstep(1.97, 1.5, abs(X)); } vec2 ridgeUV(vec3 q, float a, float zb){ float h = q.y - topY(q.x); float dz = q.z - zb; float ph = (1.0 - a) * 1.5708; float c = cos(ph), s = sin(ph); vec2 vw = vec2(h * c + dz * s, -h * s + dz * c); // stiff card still bows a little between its folds vw.y += vw.x * (0.05 * vw.x + 0.035 * sin(q.x * 2.1 + zb * 5.0)) * smoothstep(0.0, 0.3, vw.x); return vw; } float ridge(vec3 q, float sg, float i, float a, float zb){ if (a < 0.002) return 1e3; vec2 vw = ridgeUV(q, a, zb); float X = sg * q.x; float d2 = max(vw.x - ridgeH(X, i), -vw.x) * 0.65; if (i < 0.5) d2 = min(d2, max(length(vec2(X - 0.72, vw.x - 1.14)) - 0.27, -vw.x)); d2 = max(d2, max(-q.x, q.x - 1.98)); vec2 e = vec2(d2, (abs(vw.y) - 0.007) * 0.85); return min(max(e.x, e.y), 0.0) + length(max(e, 0.0)); } // ---- the barn on the right page: a pop-up box that rises out of the paper ---- vec3 barnP(vec3 q){ vec3 r = q - vec3(1.02, topY(1.02) - 0.004, 0.66); r.y /= clamp(uA.w, 0.03, 1.2); return r; } float barn(vec3 q){ if (uA.w < 0.01) return 1e3; vec3 r = barnP(q); float body = sdBox(r - vec3(0.0, 0.2, 0.0), vec3(0.34, 0.2, 0.2), 0.004); vec2 rz = vec2(abs(r.z), r.y - 0.4); float roof = max(abs(r.x) - 0.4, max(dot(rz, vec2(0.6, 0.8)) - 0.15, -rz.y)); float ch = sdBox(r - vec3(0.22, 0.56, -0.05), vec3(0.035, 0.1, 0.035), 0.003); return min(min(body, roof), ch) * min(uA.w, 1.0) * 0.9; } // ---- the tea tin on the left page ---- vec3 tinP(vec3 q){ vec3 r = q - vec3(1.0, topY(1.0) - 0.004, 0.72); r.y /= clamp(uTin, 0.03, 1.2); return r; } float tin(vec3 q){ if (uTin < 0.01) return 1e3; vec3 r = tinP(q); float body = sdCyl(r - vec3(0.0, 0.25, 0.0), 0.24, 0.25, 0.012); float lid = sdCyl(r - vec3(0.0, 0.47, 0.0), 0.252, 0.06, 0.012); return min(body, lid) * min(uTin, 1.0) * 0.9; } const vec3 ZB = vec3(-0.95, -0.42, 0.06); vec2 map(vec3 p){ vec3 L = toLeft(p); vec2 r = halfBook(p); vec2 l = halfBook(L); if (l.x < r.x) r = l; float d = min(ridge(p, 1.0, 0.0, uA.x, ZB.x), ridge(L, -1.0, 0.0, uA.x, ZB.x)); if (d < r.x) r = vec2(d, 3.0); d = min(ridge(p, 1.0, 1.0, uA.y, ZB.y), ridge(L, -1.0, 1.0, uA.y, ZB.y)); if (d < r.x) r = vec2(d, 4.0); d = min(ridge(p, 1.0, 2.0, uA.z, ZB.z), ridge(L, -1.0, 2.0, uA.z, ZB.z)); if (d < r.x) r = vec2(d, 5.0); d = barn(p); if (d < r.x) r = vec2(d, 6.0); d = tin(L); if (d < r.x) r = vec2(d, 7.0); return r; } vec3 calcN(vec3 p){ vec2 e = vec2(0.0007, -0.0007); return normalize(e.xyy * map(p + e.xyy).x + e.yyx * map(p + e.yyx).x + e.yxy * map(p + e.yxy).x + e.xxx * map(p + e.xxx).x); } vec2 boxSpan(vec3 ro, vec3 rd, vec3 lo, vec3 hi){ vec3 inv = 1.0 / (rd + vec3(1e-6)); vec3 a = (lo - ro) * inv; vec3 b = (hi - ro) * inv; vec3 mn = min(a, b); vec3 mx = max(a, b); return vec2(max(max(mn.x, mn.y), max(mn.z, 0.0)), min(mx.x, min(mx.y, mx.z))); } const vec3 BLO = vec3(-2.3, -0.01, -1.7); const vec3 BHI = vec3(2.3, 2.45, 1.7); float shadow(vec3 ro){ vec2 tb = boxSpan(ro, uL, BLO, BHI); if (tb.x > tb.y) return 1.0; float res = 1.0; float t = max(tb.x, 0.012); for (int i = 0; i < 44; i++) { float h = map(ro + uL * t).x; res = min(res, 14.0 * h / t); t += clamp(h, 0.01, 0.25); if (res < 0.002 || t > tb.y) break; } res = clamp(res, 0.0, 1.0); return res * res * (3.0 - 2.0 * res); } float calcAO(vec3 p, vec3 n){ float o = 0.0; float s = 1.0; for (int i = 1; i <= 5; i++) { float h = 0.012 + 0.05 * float(i); float d = min(map(p + n * h).x, p.y + n.y * h); o += (h - d) * s; s *= 0.7; } return clamp(1.0 - 2.0 * o, 0.0, 1.0); } vec3 sky(vec3 r){ vec3 c = mix(vec3(0.82, 0.76, 0.68), vec3(0.72, 0.78, 0.88), smoothstep(-0.1, 0.9, r.y)); c += SUN * 3.0 * pow(max(dot(r, uL), 0.0), 24.0); return c * 0.8; } vec3 light(vec3 p, vec3 n, float occ, float sh){ float ndl = max(dot(n, uL), 0.0); vec3 amb = mix(vec3(0.5, 0.45, 0.4), vec3(0.62, 0.68, 0.8), 0.5 + 0.5 * n.y) * occ; // the table throws warm light back up into the undersides vec3 bounce = vec3(0.7, 0.58, 0.44) * clamp(0.6 - 0.5 * n.y, 0.0, 1.0) * 0.32 * occ; return SUN * 3.4 * ndl * sh + amb * 0.42 + bounce; } // ---- what each surface is made of ---- vec3 albedo(float m, vec3 p, vec3 n, inout float gloss, out float thin){ thin = 0.0; if (m < 1.5) { // book cloth: a fine linen weave in ink blue vec3 q = p; float w = n2(q.xz * 260.0) * 0.5 + n2(q.zy * 260.0) * 0.5; gloss = 0.18; vec3 c = vec3(0.03, 0.05, 0.1) * (0.8 + 0.4 * w); // the title blocked in gold on the front board, which is the underside of the left half vec3 L = toLeft(p); if (L.y < 0.006 && halfBook(L).x < halfBook(p).x + 0.001) { float g = texture2D(uTex, vec2(0.5 - L.x / 4.1, (L.z + 1.45) / 2.9)).g; c = mix(c, vec3(0.5, 0.34, 0.12), g); gloss = mix(gloss, 0.9, g); } return c; } if (m < 2.5) { vec3 R = p; float sg = 1.0; if (halfBook(toLeft(p)).x < halfBook(p).x) { R = toLeft(p); sg = -1.0; } vec3 a = vec3(0.86, 0.82, 0.73); if (R.y < topY(R.x) - 0.006) a *= 0.86 + 0.14 * sin(R.y * 1700.0 + n2(R.xz * 40.0) * 3.0); // the edges of the leaves else { float ink = texture2D(uTex, vec2(0.5 + sg * R.x / 4.1, (R.z + 1.45) / 2.9)).r; a = mix(a, vec3(0.14, 0.12, 0.1), ink * 0.85); } a *= 0.95 + 0.07 * n2(p.xz * 90.0); return a; } if (m < 5.5) { float i = m - 3.0; vec3 R = p; float sg = 1.0; float z = i < 0.5 ? ZB.x : i < 1.5 ? ZB.y : ZB.z; float a = i < 0.5 ? uA.x : i < 1.5 ? uA.y : uA.z; vec2 vr = ridgeUV(p, a, z), vl = ridgeUV(toLeft(p), a, z); if (abs(vl.y) < abs(vr.y)) { R = toLeft(p); sg = -1.0; } vec2 vw = ridgeUV(R, a, z); float X = sg * R.x; float ph = (1.0 - a) * 1.5708; float ly = -sin(ph); vec3 pn = sg > 0.0 ? vec3(0.0, ly, cos(ph)) : vec3(ly * sin(uTh), ly * cos(uTh), cos(ph)); vec3 c = i < 0.5 ? vec3(0.5, 0.58, 0.45) : i < 1.5 ? vec3(0.24, 0.4, 0.27) : vec3(0.08, 0.22, 0.14); if (i < 0.5 && length(vec2(X - 0.72, vw.x - 1.14)) < 0.27 && vw.x > ridgeH(X, 0.0) - 0.002) c = vec3(0.78, 0.46, 0.17); // rows of tea bushes printed on the front ridge if (i > 1.5) c *= 0.82 + 0.25 * smoothstep(0.2, 0.8, sin(vw.x * 70.0 + sin(X * 3.0) * 2.0)); // a cut edge shows the paler core of the coloured card float edge = 1.0 - smoothstep(0.55, 0.85, abs(dot(n, pn))); c = mix(c, vec3(0.88, 0.85, 0.76), edge * 0.75); thin = 1.0 - edge; c *= 0.94 + 0.1 * n2(vec2(X, vw.x) * 120.0); return c; } if (m < 6.5) { vec3 r = barnP(p); if (r.y > 0.4 || (r.y > 0.45 && abs(r.x) < 0.3)) { float tile = smoothstep(0.35, 0.5, abs(fract(r.y * 26.0) - 0.5)); return vec3(0.1, 0.095, 0.09) * (0.85 + 0.3 * tile); } if (abs(r.x - 0.22) < 0.04 && r.y > 0.45) return vec3(0.42, 0.18, 0.11); vec3 c = vec3(0.6, 0.2, 0.1); float boards = smoothstep(0.42, 0.5, abs(fract(r.x * 30.0) - 0.5)); c *= 0.9 + 0.12 * boards; if (r.z > 0.19 && abs(r.x) < 0.09 && r.y < 0.25) c = vec3(0.17, 0.08, 0.05); if (r.z > 0.19 && abs(abs(r.x) - 0.22) < 0.05 && abs(r.y - 0.24) < 0.05) c = vec3(0.95, 0.8, 0.52); if (r.z > 0.19 && abs(r.x) < 0.25 && abs(r.y - 0.34) < 0.012) c = vec3(0.86, 0.82, 0.72); return c * (0.95 + 0.08 * n2(p.xy * 140.0)); } vec3 r = tinP(p); vec3 c = vec3(0.03, 0.22, 0.24); if (r.y > 0.41) c = vec3(0.3, 0.17, 0.08); else if (abs(r.y - 0.23) < 0.1) { c = vec3(0.88, 0.82, 0.68); float ang = atan(r.x, r.z); if (abs(r.y - 0.23) > 0.082) c = vec3(0.3, 0.17, 0.08); else if (abs(ang) < 0.55 && abs(r.y - 0.24) < 0.022) c = vec3(0.05, 0.2, 0.2); else if (abs(ang) < 0.32 && abs(r.y - 0.19) < 0.008) c = vec3(0.4, 0.3, 0.2); } gloss = 0.1; return c * (0.95 + 0.08 * n2(p.xy * 140.0)); } vec3 shade(vec3 p, vec3 n, vec3 rd, float m){ float occ = calcAO(p, n); float gloss = 0.03; float thin; vec3 a = albedo(m, p, n, gloss, thin); float sh = shadow(p + n * 0.006); vec3 col = a * light(p, n, occ, sh); // light coming through thin card from behind if (thin > 0.0) { float back = max(dot(-n, uL), 0.0); if (back > 0.0) col += a * a * SUN * 3.4 * back * shadow(p - n * 0.02) * thin; } vec3 r = reflect(rd, n); float F = 0.03 + 0.97 * pow(1.0 - clamp(dot(-rd, n), 0.0, 1.0), 5.0); col += F * sky(r) * gloss * (0.4 + 0.6 * occ) * (0.4 + 0.6 * sh); return col; } vec3 backdrop(vec3 rd){ return mix(vec3(0.9, 0.84, 0.76), vec3(0.72, 0.66, 0.58), smoothstep(-0.25, 0.25, rd.y)); } vec3 floorCol(vec3 p, float t, vec3 rd){ float w = n2(vec2(p.x * 160.0, p.z * 9.0)) * 0.5 + n2(vec2(p.x * 9.0, p.z * 160.0)) * 0.5; vec3 a = vec3(0.7, 0.63, 0.53) * (0.92 + 0.12 * w) * (0.96 + 0.06 * n2(p.xz * 1.5)); vec3 n = vec3(0.0, 1.0, 0.0); float occ = calcAO(p, n); float sh = shadow(p + n * 0.004); vec3 c = a * light(p, n, occ, sh); return mix(c, backdrop(rd), smoothstep(9.0, 26.0, t)); } void main(){ vec2 fc = gl_FragCoord.xy + uJit.xy; vec2 uv = (fc - 0.5 * uRes) / uRes.y - uShift; vec3 fw = normalize(uTgt - uCam); vec3 rt = normalize(cross(fw, vec3(0.0, 1.0, 0.0))); vec3 up = cross(rt, fw); vec3 rd = normalize(fw * uFoc + rt * uv.x + up * uv.y); vec3 ro = uCam; vec3 fp = ro + rd * (uFocus / dot(rd, fw)); ro += rt * uJit.z + up * uJit.w; rd = normalize(fp - ro); float tf = rd.y < 0.0 ? -ro.y / rd.y : 1e9; vec2 tb = boxSpan(ro, rd, BLO, BHI); float t = -1.0; float m = 0.0; if (tb.x < tb.y) { float s = tb.x; for (int i = 0; i < 140; i++) { vec2 h = map(ro + rd * s); if (h.x < 0.0003 * s) { t = s; m = h.y; break; } s += h.x; if (s > tb.y) break; } } vec3 col; if (t > 0.0) { vec3 p = ro + rd * t; col = shade(p, calcN(p), rd, m); } else if (tf < 1e8) col = floorCol(ro + rd * tf, tf, rd); else col = backdrop(rd); col = min(col, vec3(24.0)); if (uDirect > 0.5) col = tone(col); outC = vec4(col, 1.0); } `; // Developing: a soft bloom, the filmic curve, a vignette and a little grain. const POST = ` precision highp float; uniform sampler2D uAcc; uniform vec2 uRes; uniform float uGrain; uniform vec2 uCentre; ${TONE} float h21(vec2 p){ vec3 q = fract(vec3(p.xyx) * 0.1031); q += dot(q, q.yzx + 33.33); return fract((q.x + q.y) * q.z); } void main(){ vec2 uv = gl_FragCoord.xy / uRes; vec3 c = texture2D(uAcc, uv).rgb; vec3 b = vec3(0.0); for (int i = 0; i < 16; i++) { float a = float(i) * 2.39996; float r = sqrt((float(i) + 0.5) / 16.0); vec3 s = texture2D(uAcc, uv + vec2(cos(a), sin(a)) * r * 0.018 * vec2(uRes.y / uRes.x, 1.0)).rgb; b += max(s - 1.6, 0.0) * (1.0 - 0.6 * r); } c += b * 0.012 * vec3(1.0, 0.9, 0.78); vec2 q = (uv - uCentre) * vec2(uRes.x / uRes.y, 1.0); c *= 1.0 - 0.2 * smoothstep(0.4, 1.3, length(q)); c = tone(c); c += (h21(gl_FragCoord.xy + uGrain * 91.7) - 0.5) * 0.02; outC = vec4(c, 1.0); } `; // The type printed on the spread, drawn once. Left half of the canvas is the left page. function spreadPrint() { const W = 2048, H = 1440; const cv = document.createElement("canvas"); cv.width = W; cv.height = H; const g = cv.getContext("2d"); if (!g) return cv; g.fillStyle = "#000"; g.fillRect(0, 0, W, H); g.fillStyle = "#f00"; g.textBaseline = "alphabetic"; const px = (x: number) => W / 2 + (x / 2.05) * (W / 2); // scene x on the page to canvas x const pz = (z: number) => ((z + 1.45) / 2.9) * H; g.font = `600 30px ${FONT}`; g.textAlign = "left"; g.fillText("FERNMOOR", px(-1.82), pz(-1.24)); g.textAlign = "right"; g.fillText("SPRING PICKING", px(1.82), pz(-1.24)); g.font = `italic 44px ${SERIF}`; g.textAlign = "left"; const lines = ["The mist sits in the valley until nine.", "By then the first baskets are full and", "the pickers walk them down to the barn."]; lines.forEach((l, i) => g.fillText(l, px(-1.82), pz(1.02) + i * 58)); g.textAlign = "right"; ["Nothing is hurried. A leaf that is rushed", "tastes of the hurry, the old growers say."].forEach((l, i) => g.fillText(l, px(1.82), pz(1.1) + i * 58)); // the cover title, in green so the shader can tell it from the page ink g.fillStyle = "#0f0"; g.textAlign = "center"; g.font = `700 104px ${FONT}`; g.save(); g.translate(px(-1.02), pz(-0.25)); g.scale(-1, 1); g.fillText("FERNMOOR", 0, 0); g.font = `italic 56px ${SERIF}`; g.fillText("A spring picking", 0, 96); g.restore(); g.fillStyle = "#f00"; g.font = `500 30px ${FONT}`; g.textAlign = "left"; g.fillText("14", px(-1.82), pz(1.36)); g.textAlign = "right"; g.fillText("15", px(1.82), pz(1.36)); return cv; } // No WebGL: the open book drawn flat, at its finished state. function Still() { return ( ); } export default function PaperPopUpBookScrollStory() { const stage = useRef(null); const canvas = useRef(null); const [beat, setBeat] = useState(2); const [shown, setShown] = useState<"wait" | "gl" | "still">("wait"); const beatRef = useRef(2); const api = useRef<{ go: (p: number) => void } | null>(null); useEffect(() => { const box = stage.current, cv = canvas.current; if (!box || !cv) return; const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches; const opts = { antialias: false, alpha: false, powerPreference: "high-performance" as const }; const gl2 = cv.getContext("webgl2", opts) as WebGL2RenderingContext | null; const gl = (gl2 ?? cv.getContext("webgl", opts)) as WebGLRenderingContext | null; if (!gl) { setShown("still"); return; } const canAcc = !!gl2 && (!!gl2.getExtension("EXT_color_buffer_float") || !!gl2.getExtension("EXT_color_buffer_half_float")); const info = gl.getExtension("WEBGL_debug_renderer_info"); const renderer = info ? String(gl.getParameter(info.UNMASKED_RENDERER_WEBGL)) : ""; const software = /swiftshader|llvmpipe|software|basic render/i.test(renderer); const still = reduce || software; const head = gl2 ? "#version 300 es\n#define ATTR in\n" : "#define ATTR attribute\n"; const fhead = gl2 ? "#version 300 es\n#define texture2D texture\nprecision highp float;\nout vec4 outC;\n" : "#define outC gl_FragColor\n"; const compile = (type: number, src: string) => { const sh = gl.createShader(type); if (!sh) return null; gl.shaderSource(sh, src); gl.compileShader(sh); return gl.getShaderParameter(sh, gl.COMPILE_STATUS) ? sh : null; }; const link = (frag: string) => { const v = compile(gl.VERTEX_SHADER, head + VERT), f = compile(gl.FRAGMENT_SHADER, fhead + frag); const p = gl.createProgram(); if (!v || !f || !p) return null; gl.attachShader(p, v); gl.attachShader(p, f); gl.bindAttribLocation(p, 0, "aPos"); gl.linkProgram(p); return gl.getProgramParameter(p, gl.LINK_STATUS) ? p : null; }; const scene = link(SCENE), post = canAcc ? link(POST) : null; if (!scene || (canAcc && !post)) { setShown("still"); return; } const U = (p: WebGLProgram, n: string) => gl.getUniformLocation(p, n); const su = Object.fromEntries(["uRes", "uJit", "uSeed", "uCam", "uTgt", "uFoc", "uShift", "uFocus", "uTh", "uA", "uTin", "uL", "uTex", "uDirect"].map((n) => [n, U(scene, n)])); const pu = post ? Object.fromEntries(["uAcc", "uRes", "uGrain", "uCentre"].map((n) => [n, U(post, n)])) : {}; const quad = gl.createBuffer(); gl.bindBuffer(gl.ARRAY_BUFFER, quad); gl.bufferData(gl.ARRAY_BUFFER, new Float32Array([-1, -1, 3, -1, -1, 3]), gl.STATIC_DRAW); gl.enableVertexAttribArray(0); gl.vertexAttribPointer(0, 2, gl.FLOAT, false, 0, 0); const tex = gl.createTexture(); gl.activeTexture(gl.TEXTURE0); gl.bindTexture(gl.TEXTURE_2D, tex); gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, spreadPrint()); gl.generateMipmap(gl.TEXTURE_2D); const aniso = gl.getExtension("EXT_texture_filter_anisotropic"); if (aniso) gl.texParameterf(gl.TEXTURE_2D, aniso.TEXTURE_MAX_ANISOTROPY_EXT, 8); gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR_MIPMAP_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); const acc = canAcc ? gl.createTexture() : null; const fbo = canAcc ? gl.createFramebuffer() : null; let W = 0, H = 0, scale = 1, cssW = 1, cssH = 1; // It opens already open: the finished spread is what the first second shows. const s = { p: 1, T: 1, th: 0, thv: 0, a: RISE.map(() => 1), av: RISE.map(() => 0), px: 0, py: 0, sx: 0, sy: 0, count: 0, fresh: true, frame: 0, slow: 0, visible: true, raf: 0, last: 0, t0: 0, touched: false, first: true, fpsN: 0, fpsT: 0, }; const size = () => { const r = box.getBoundingClientRect(); cssW = Math.max(1, r.width); cssH = Math.max(1, r.height); const dpr = Math.min(software ? 1 : 1.5, window.devicePixelRatio || 1) * scale; const k = Math.min(1, Math.sqrt(1.2e6 / (cssW * cssH * dpr * dpr))); const w = Math.max(2, Math.round(cssW * dpr * k)), h = Math.max(2, Math.round(cssH * dpr * k)); if (w === W && h === H) return; W = w; H = h; cv.width = W; cv.height = H; if (gl2 && acc && fbo) { gl.activeTexture(gl.TEXTURE1); gl.bindTexture(gl.TEXTURE_2D, acc); gl2.texImage2D(gl.TEXTURE_2D, 0, gl2.RGBA16F, W, H, 0, gl.RGBA, gl2.HALF_FLOAT, null); 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.bindFramebuffer(gl.FRAMEBUFFER, fbo); gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, acc, 0); gl.bindFramebuffer(gl.FRAMEBUFFER, null); } s.count = 0; s.fresh = true; }; const halton = (i: number, b: number) => { let f = 1, r = 0; while (i > 0) { f /= b; r += f * (i % b); i = Math.floor(i / b); } return r; }; // A three-quarter view from the front and a little to the right, as if the book lay on your desk. const camera = () => { const wide = cssW >= 1024, aspect = cssW / cssH; const el = (wide ? 0.6 : 0.68) - s.sy * 0.03, az = 0.2 + s.sx * 0.08, dist = 11; const tgt = [0.0, 0.42, 0.05]; const cam = [tgt[0] + dist * Math.sin(az) * Math.cos(el), tgt[1] + dist * Math.sin(el), tgt[2] + dist * Math.cos(az) * Math.cos(el)]; const foc = wide ? 1.9 * Math.min(1, aspect / 1.65) : 1.04 * Math.min(1.5, aspect / 0.5); const shift = wide ? [0.24 * aspect / 1.68, -0.03] : [0.0, 0.15]; return { cam, tgt, foc, shift, wide }; }; const draw = (alpha: number, sample: number) => { const c = camera(); const jx = sample ? halton(sample, 2) - 0.5 : 0, jy = sample ? halton(sample, 3) - 0.5 : 0; const la = halton(sample, 5) * Math.PI * 2, lr = sample ? Math.sqrt(halton(sample, 7)) * 0.06 : 0; gl.useProgram(scene); gl.bindFramebuffer(gl.FRAMEBUFFER, canAcc ? fbo : null); gl.viewport(0, 0, W, H); if (canAcc && alpha < 1) { gl.enable(gl.BLEND); gl.blendColor(0, 0, 0, alpha); gl.blendFunc(gl.CONSTANT_ALPHA, gl.ONE_MINUS_CONSTANT_ALPHA); } else gl.disable(gl.BLEND); gl.uniform2f(su.uRes, W, H); gl.uniform4f(su.uJit, canAcc ? jx : 0, canAcc ? jy : 0, canAcc ? Math.cos(la) * lr : 0, canAcc ? Math.sin(la) * lr : 0); gl.uniform1f(su.uSeed, canAcc && sample ? (sample * 0.61803) % 1 || 0.5 : 0); gl.uniform3f(su.uCam, c.cam[0], c.cam[1], c.cam[2]); gl.uniform3f(su.uTgt, c.tgt[0], c.tgt[1], c.tgt[2]); gl.uniform1f(su.uFoc, c.foc); gl.uniform2f(su.uShift, c.shift[0], c.shift[1]); gl.uniform1f(su.uFocus, Math.hypot(c.cam[0], c.cam[1] - 0.4, c.cam[2] - 0.2)); gl.uniform1f(su.uTh, s.th); gl.uniform4f(su.uA, s.a[0], s.a[1], s.a[2], s.a[3]); gl.uniform1f(su.uTin, s.a[4]); const lx = -0.7, ly = 0.72, lz = -0.36, ll = Math.hypot(lx, ly, lz); gl.uniform3f(su.uL, lx / ll, ly / ll, lz / ll); gl.uniform1i(su.uTex, 0); gl.uniform1f(su.uDirect, canAcc ? 0 : 1); gl.drawArrays(gl.TRIANGLES, 0, 3); if (canAcc && post) { gl.bindFramebuffer(gl.FRAMEBUFFER, null); gl.disable(gl.BLEND); gl.useProgram(post); gl.uniform1i(pu.uAcc, 1); gl.uniform2f(pu.uRes, W, H); gl.uniform1f(pu.uGrain, still ? 1 : s.frame % 64); gl.uniform2f(pu.uCentre, c.wide ? 0.62 : 0.5, c.wide ? 0.45 : 0.62); gl.drawArrays(gl.TRIANGLES, 0, 3); } }; // Every target follows from one number: how far through the story the reader is. const targets = (p: number) => ({ th: Math.PI * (1 - sm(COVER[0], COVER[1], p)), a: RISE.map(([a, b]) => sm(a, b, p)) }); const snap = () => { const t = targets(s.p); s.th = t.th; s.thv = 0; s.a = t.a; s.av = RISE.map(() => 0); s.count = 0; }; const setP = (p: number) => { s.T = Math.max(0, Math.min(1, p)); if (reduce) { s.p = s.T; snap(); } const b = beatOf(reduce ? s.p : s.T); if (b !== beatRef.current) { beatRef.current = b; setBeat(b); } wake(); }; api.current = { go: (p: number) => { s.touched = true; setP(p); } }; // The self-running demo: hold the open spread, close it, then open it a fold at a time. const demo = (ms: number) => { if (ms < 5200) return 1; const t = ((ms - 5200) / 1000) % 14; return t < 2 ? 0 : t < 4.8 ? beats[0].at : t < 7.6 ? beats[1].at : 1; }; const frame = (now: number) => { s.raf = 0; if (!s.visible) return; const dtRaw = s.last ? (now - s.last) / 1000 : 0.016; const dt = Math.min(0.033, dtRaw); s.last = now; s.frame++; if (!s.t0) s.t0 = now; if (!still && !s.touched) { const d = demo(now - s.t0); if (d !== s.T) setP(d); } let moving = false; if (!reduce) { s.p += (s.T - s.p) * (1 - Math.exp(-dt * 2.6)); if (Math.abs(s.T - s.p) < 0.0005) s.p = s.T; const tg = targets(s.p); const sub = 4, h = dt / sub; for (let k = 0; k < sub; k++) { // the board is heavy: it lands, bounces once off the table and settles s.thv += (62 * (tg.th - s.th) - 8.5 * s.thv) * h; s.th += s.thv * h; if (s.th < 0) { s.th = 0; if (s.thv < 0) s.thv *= -0.22; } // card springs up past upright and sways back for (let i = 0; i < RISE.length; i++) { s.av[i] += (150 * (tg.a[i] - s.a[i]) - 9 * s.av[i]) * h; s.a[i] = Math.max(0, s.a[i] + s.av[i] * h); } } if (Math.abs(s.T - s.p) > 0 || Math.abs(s.thv) > 0.002 || Math.abs(tg.th - s.th) > 0.001 || s.av.some((v, i) => Math.abs(v) > 0.002 || Math.abs(tg.a[i] - s.a[i]) > 0.001)) moving = true; } if (!still) { const ox = s.sx, oy = s.sy; s.sx += (s.px - s.sx) * (1 - Math.exp(-dt * 3)); s.sy += (s.py - s.sy) * (1 - Math.exp(-dt * 3)); if (Math.abs(s.sx - ox) + Math.abs(s.sy - oy) > 1e-4) moving = true; } if (s.fresh || !canAcc) { draw(1, 0); s.fresh = false; s.count = 1; } else if (moving) { draw(0.55, 1 + (s.frame % 64)); s.count = 3; } else if (s.count < 36) { s.count++; draw(1 / s.count, s.count); } if (s.first) { s.first = false; setShown("gl"); } if (!still && dtRaw > 0.026) s.slow++; else s.slow = Math.max(0, s.slow - 2); if (s.slow > 45 && scale > 0.5) { scale *= 0.82; s.slow = 0; size(); } s.fpsN++; if (now - s.fpsT > 1000) { box.dataset.fps = String(Math.round((s.fpsN * 1000) / (now - s.fpsT))); s.fpsN = 0; s.fpsT = now; } if (moving || s.count < 36 || (!still && !s.touched)) s.raf = requestAnimationFrame(frame); }; const wake = () => { if (!s.raf && s.visible) { s.last = 0; s.raf = requestAnimationFrame(frame); } }; // Scrolling drives the story once the reader starts to scroll: closed as the book enters the // window, fully open by the time it sits in the middle. const onScroll = () => { const r = box.getBoundingClientRect(), vh = window.innerHeight || 800; if (r.bottom < 0 || r.top > vh) return; s.touched = true; setP((vh * 0.95 - r.top) / (vh * 0.95 - Math.max(0, (vh - r.height) / 2) + 1)); }; size(); const ro = new ResizeObserver(() => { size(); wake(); }); ro.observe(box); const io = new IntersectionObserver(([e]) => { s.visible = e.isIntersecting && !document.hidden; if (s.visible) wake(); }, { threshold: 0.02 }); io.observe(box); const vis = () => { s.visible = !document.hidden; if (s.visible) wake(); }; document.addEventListener("visibilitychange", vis); window.addEventListener("scroll", onScroll, { passive: true }); const move = (e: PointerEvent) => { const r = box.getBoundingClientRect(); s.px = ((e.clientX - r.left) / r.width) * 2 - 1; s.py = ((e.clientY - r.top) / r.height) * 2 - 1; if (!still) wake(); }; const leave = () => { s.px = 0; s.py = 0; }; box.addEventListener("pointermove", move); box.addEventListener("pointerleave", leave); const lost = (e: Event) => { e.preventDefault(); setShown("still"); }; cv.addEventListener("webglcontextlost", lost); wake(); return () => { cancelAnimationFrame(s.raf); ro.disconnect(); io.disconnect(); document.removeEventListener("visibilitychange", vis); window.removeEventListener("scroll", onScroll); box.removeEventListener("pointermove", move); box.removeEventListener("pointerleave", leave); cv.removeEventListener("webglcontextlost", lost); api.current = null; }; }, []); const choose = (i: number) => { if (api.current) api.current.go(beats[i].at); else { beatRef.current = i; setBeat(i); } }; const keys = (e: React.KeyboardEvent, i: number) => { const next = e.key === "ArrowRight" || e.key === "ArrowDown" ? i + 1 : e.key === "ArrowLeft" || e.key === "ArrowUp" ? i - 1 : e.key === "Home" ? 0 : e.key === "End" ? beats.length - 1 : -9; if (next === -9) return; e.preventDefault(); const k = Math.max(0, Math.min(beats.length - 1, next)); choose(k); document.getElementById(`ppb-fold-${k}`)?.focus(); }; const b = beats[beat]; return (
); } ```