# Glass Lens Carousel
A looping image strip that is never drawn straight to screen: it renders to an offscreen texture, then a fullscreen pass samples it back through a thick optical element - drawing the picture inward, separating it into colour channels toward the perimeter, and adding a bright core, a modulated ring and an undulating edge. Scroll or drag to travel it; click a panel to bring it forward and enlarge it. Two WebGL2 passes, no 3D library.
- Demo: https://crafterui.com/components/glass-lens-carousel
- Install: `npx @crafterui/cli@latest components add glass-lens-carousel` - or `npx shadcn@latest add https://crafterui.com/r/glass-lens-carousel.json`
- Installs to: `registry/crafterui/ui/glass-lens-carousel.tsx`
## Usage
```tsx
"use client"
import {
GlassLensCarousel,
type GlassLensItem,
} from "@/registry/crafterui/ui/glass-lens-carousel"
// Placeholder imagery collected from Pinterest, saved under public/work. Swap
// the paths and the copy for your own index - the row sizes itself to however
// many pieces it is handed, and each panel keeps its picture's own aspect.
const WORK: GlassLensItem[] = [
{ image: "/work/verdant.jpg", title: "Verdant", caption: "Outerwear editorial" },
{ image: "/work/ember-field.jpg", title: "Ember Field", caption: "Colour campaign, stills" },
{ image: "/work/northbound.jpg", title: "Northbound", caption: "Winter collection campaign" },
{ image: "/work/marigold.jpg", title: "Marigold", caption: "Harvest editorial" },
{ image: "/work/signal-grid.jpg", title: "Signal Grid", caption: "Identity and type system" },
{ image: "/work/riot-press.jpg", title: "Riot Press", caption: "Print series, risograph" },
{ image: "/work/nightshift.jpg", title: "Nightshift", caption: "Automotive launch film" },
{ image: "/work/cold-chrome.jpg", title: "Cold Chrome", caption: "Showroom art direction" },
{ image: "/work/spectral.jpg", title: "Spectral", caption: "Motion identity" },
{ image: "/work/dune-study.jpg", title: "Dune Study", caption: "Art direction study" },
{ image: "/work/afterlight.jpg", title: "Afterlight", caption: "Short film, direction" },
{ image: "/work/redstone.jpg", title: "Redstone", caption: "Location campaign" },
]
export default function GlassLensCarouselDemo() {
return (
)
}
```
## Source - `registry/crafterui/ui/glass-lens-carousel.tsx`
```tsx
"use client"
// A continuous strip of work viewed through a thick optical element.
//
// The strip is unremarkable on its own: panels of equal height, each holding
// its source aspect, cycling so there is no end to arrive at. The interest is
// in the second stage. The strip is never rasterised to the display - it goes
// to an offscreen texture, and a fullscreen triangle pair samples that texture
// back through an optic that draws the image inward, separates it into colour
// channels toward its perimeter, and adds a bright core, a modulated ring and a
// perimeter that undulates as the strip travels behind it.
//
// Two stages, one canvas, no scene graph. Every term the optic needs is a
// function of radial position, so it fits in a page of shader code.
import * as React from "react"
import { cn } from "@/lib/utils"
export interface GlassLensItem {
/** Cover art. Cross-origin sources must send CORS headers. */
image: string
/** Shown while this panel is centred. */
title: string
/** The line under the title. */
caption?: string
}
export interface GlassLensCarouselProps
extends Omit, "children"> {
items: GlassLensItem[]
/** Wordmark in the top-left. Omit to drop it. @default undefined */
brand?: string
/** Panel height, as a fraction of the stage. @default 0.62 */
panelHeight?: number
/** Space between panels, in px. @default 12 */
gap?: number
/** Panel corner radius, in px. @default 6 */
radius?: number
/** The lens ring and aura colour. @default "#009dff" */
tint?: string
/** Click a panel to centre and enlarge it. @default true */
focusable?: boolean
/** Label on the focused panel's dismiss control. @default "Close" */
closeLabel?: string
/** Extra classes on the root surface. @default undefined */
className?: string
}
/* Motion characteristics. The strip is deliberately weighty; a low convergence
rate is most of what makes the optic register as a physical thickness rather
than a filter applied over an ordinary carousel. */
const EASE = 0.09 // fraction of the remaining distance closed each frame
const SNAP_EASE = 0.05 // ... and once it is settling onto a panel
const DRAG_EASE = 0.24 // ... and while a finger or cursor is pulling it
const WHEEL = 1.4
const DRAG = 1.6
const FRICTION = 0.865 // flick decay after a drag release
const SNAP_IDLE = 120 // ms of quiet input before the row settles on a panel
const CLICK_SLOP = 6 // px of travel that still counts as a click
/* Panels contract as travel speed rises, which suggests resistance acting on
something with mass. The threshold below is the per-frame speed at which the
full contraction is reached. */
const SHRINK_MAX = 60
const SHRINK_ATTACK = 0.25
const SHRINK_DECAY = 0.06
/* Expanded view: the chosen panel enlarges and remains, the others withdraw
from the centre outward, and the optic dissolves as they leave. */
const FOCUS_EASE = 0.085
const FOCUS_STAGGER = 0.055
const FOCUS_DROP = 1.4 // how far a panel falls, in stage heights
const FOCUS_GROW = 0.18
/* Introduction: panels rise into place from beneath at reduced size, beginning
with the pair nearest the centre. */
const ENTRY_SECONDS = 1.15
const ENTRY_STAGGER = 0.07
const ENTRY_START = 0.22 // height they start at, of their final height
/** Interval, in frames, between palette reads. Resolving a token forces a style
recalculation, and the palette only changes when someone toggles the theme. */
const THEME_EVERY = 20
const clamp = (v: number, lo: number, hi: number) => Math.min(hi, Math.max(lo, v))
const lerp = (a: number, b: number, t: number) => a + (b - a) * t
/** Fifth-order ease-out. The extended tail lets a movement settle rather than
terminate abruptly. */
const outQuint = (t: number) => 1 - Math.pow(1 - clamp(t, 0, 1), 5)
const PANEL_VERT = /* glsl */ `#version 300 es
in vec2 aPos;
uniform vec4 uRect; // centre.xy, size.xy - px, origin at the stage centre
uniform vec2 uRes;
out vec2 vUv;
out vec2 vLocal; // px from the panel centre, for the corner cut
void main() {
vUv = vec2(aPos.x, 1.0 - aPos.y);
vLocal = (aPos - 0.5) * uRect.zw;
gl_Position = vec4((uRect.xy + vLocal) / (uRes * 0.5), 0.0, 1.0);
}`
const PANEL_FRAG = /* glsl */ `#version 300 es
precision highp float;
in vec2 vUv;
in vec2 vLocal;
uniform sampler2D uTex;
uniform vec4 uRect;
uniform vec3 uBg;
uniform float uFade; // still loading -> the panel is only its own shadow
uniform float uRadius;
out vec4 fragColor;
float sdRoundBox(vec2 p, vec2 b, float r) {
vec2 q = abs(p) - b + r;
return min(max(q.x, q.y), 0.0) + length(max(q, 0.0)) - r;
}
void main() {
// Corners are clipped rather than alpha-blended. The strip is opaque and the
// surface behind it is the identical colour, so there is nothing to blend.
float d = sdRoundBox(vLocal, uRect.zw * 0.5, min(uRadius, min(uRect.z, uRect.w) * 0.5));
if (d > 0.0) discard;
fragColor = vec4(mix(uBg, texture(uTex, vUv).rgb, uFade), 1.0);
}`
const LENS_VERT = /* glsl */ `#version 300 es
in vec2 aPos;
out vec2 vUv;
void main() {
vUv = aPos;
gl_Position = vec4(aPos * 2.0 - 1.0, 0.0, 1.0);
}`
/* The optic. A single elliptical region, rotated away from vertical and
extending past the frame vertically, so it presents as a diagonal band across
the view rather than a bubble within it. The normalised radius runs from 0 at
the centre to 1 at the boundary, and every term that follows - perimeter
undulation, channel separation, core, ring, boundary highlight - is a function
of that one quantity. Beyond the boundary the strip is passed through
unaltered, which is what gives the element a locatable edge.
A single scalar attenuates the entire effect, letting the introduction bring
it up and the expanded view take it away without a second code path. */
const LENS_FRAG = /* glsl */ `#version 300 es
precision highp float;
#define SAMPLES 12
in vec2 vUv;
uniform sampler2D uTex;
uniform float uAspect;
uniform float uTime;
uniform float uStrength;
uniform vec3 uTint;
out vec4 fragColor;
const float SIZE_X = 0.565; // half-width, in screen-height units
const float SIZE_Y = 1.0; // half-height - past the frame, so it never closes
const float ROTATION = 1.13446; // 65 degrees
const float DISPERSION = 11.0;
const float GLOW = 4.2;
const float WHITE_GLOW = 0.24;
const float NOVA_SIZE = 12.0;
const float RING = 6.0;
const float RING_RADIUS = 0.49;
const float RING_WIDTH = 0.014;
const float SHIMMER_FREQ = 12.0;
const float SHIMMER_SPEED = 3.5;
const float SHIMMER_DEPTH = 0.12;
const float RIM_START = 0.578;
const float RIM_TANGENTIAL = 0.6;
const float RIM_FREQ_1 = 2.0;
const float RIM_FREQ_2 = 1.0;
const float RIM_LINE = 1.4;
const float RIM_LINE_POS = 0.488;
const float RIM_LINE_WIDTH = 0.003;
void main() {
vec3 base = texture(uTex, vUv).rgb;
// Converted to local coordinates, corrected for aspect, then rotated, so the
// region and all of its internal structure turn as one.
vec2 offset = vUv - 0.5;
vec2 p = vec2(offset.x * uAspect, offset.y);
float ca = cos(ROTATION), sa = sin(ROTATION);
p = mat2(ca, -sa, sa, ca) * p;
float nd = length(p / vec2(SIZE_X, SIZE_Y));
if (nd > 1.0 || uStrength < 0.001) {
fragColor = vec4(base, 1.0);
return;
}
float shape = clamp(nd, 0.0, 1.0);
vec2 radial = normalize(offset + 1e-6);
vec2 tangent = vec2(-radial.y, radial.x);
float angle = atan(p.y, p.x);
// Perimeter undulation, applied tangentially so the strip travels along the
// boundary rather than being displaced outward through it.
float rim = smoothstep(RIM_START, 1.0, nd);
float wave = sin(angle * RIM_FREQ_1) * 0.55 + sin(angle * RIM_FREQ_2) * 0.25;
vec2 baseUV = 0.5 + offset
+ tangent * wave * rim * (SIZE_X + SIZE_Y) * 0.5 * RIM_TANGENTIAL * uStrength;
// Channel separation: a single run of taps along the radial direction, each
// weighted per channel and normalised afterwards, so the interior stays
// neutral and only the perimeter resolves into colour.
vec2 dispDir = offset * DISPERSION * 0.004 * smoothstep(0.55, 1.0, nd) * uStrength;
vec3 col = vec3(0.0);
vec3 weight = vec3(0.0);
for (int i = 0; i < SAMPLES; i++) {
float t = float(i) / float(SAMPLES - 1);
vec3 w = vec3(
exp(-pow((t - 0.0) / 0.38, 2.0)),
exp(-pow((t - 0.5) / 0.38, 2.0)),
exp(-pow((t - 1.0) / 0.38, 2.0))
);
col += texture(uTex, baseUV + dispDir * (t - 0.5)).rgb * w;
weight += w;
}
col /= max(weight, vec3(0.001));
// Slight darkening toward the interior - the only indication that the centre
// looks through more material than the boundary does.
col *= mix(0.91, 1.0, smoothstep(0.0, 0.38, shape));
float r2 = shape * shape * 0.25;
float gs = max(NOVA_SIZE * GLOW * 0.003, 0.004);
float nova = (exp(-r2 / gs) + exp(-r2 / (gs * 7.0)) * 0.18)
* WHITE_GLOW * (GLOW / 17.0) * 1.15;
col += vec3(nova * uStrength);
float dC = shape * 0.5;
float ring = exp(-pow((dC - RING_RADIUS) / RING_WIDTH, 2.0)) * RING * (GLOW / 17.0) * 1.8;
ring *= sin(angle * SHIMMER_FREQ + uTime * SHIMMER_SPEED) * SHIMMER_DEPTH + (1.0 - SHIMMER_DEPTH);
float aura = exp(-pow((dC - RING_RADIUS) / (RING_WIDTH * 6.0), 2.0)) * 0.28 * RING * (GLOW / 17.0);
col += uTint * (ring + aura) * uStrength;
col += vec3(exp(-pow((dC - RIM_LINE_POS) / RIM_LINE_WIDTH, 2.0)) * RIM_LINE * uStrength);
fragColor = vec4(mix(base, col, smoothstep(1.0, 0.93, nd)), 1.0);
}`
function build(gl: WebGL2RenderingContext, vert: string, frag: string) {
const program = gl.createProgram()
if (!program) return null
for (const [type, source] of [
[gl.VERTEX_SHADER, vert],
[gl.FRAGMENT_SHADER, frag],
] as const) {
const shader = gl.createShader(type)
if (!shader) return null
gl.shaderSource(shader, source)
gl.compileShader(shader)
if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
console.error(gl.getShaderInfoLog(shader))
return null
}
gl.attachShader(program, shader)
gl.deleteShader(shader)
}
gl.bindAttribLocation(program, 0, "aPos")
gl.linkProgram(program)
if (!gl.getProgramParameter(program, gl.LINK_STATUS)) {
console.error(gl.getProgramInfoLog(program))
return null
}
return program
}
/** Cached uniform handles. getUniformLocation performs a string lookup on every
call, and this sits inside the per-frame path. */
function uniforms(gl: WebGL2RenderingContext, program: WebGLProgram) {
const cache = new Map()
return (name: string) => {
let loc = cache.get(name)
if (loc === undefined) {
loc = gl.getUniformLocation(program, name)
cache.set(name, loc)
}
return loc
}
}
/** Resolves any CSS colour to 0-1 RGB by asking the browser instead of parsing
it. Theme tokens here are written in oklch, and naive comma-splitting of the
computed string yields a confidently incorrect near-black. */
function colorReader() {
const probe = document.createElement("canvas")
probe.width = probe.height = 1
const ctx = probe.getContext("2d", { willReadFrequently: true })
return (css: string): [number, number, number] => {
if (!ctx) return [0, 0, 0]
ctx.fillStyle = "#000"
ctx.fillStyle = css // left at black if the browser cannot parse it
ctx.fillRect(0, 0, 1, 1)
const [r, g, b] = ctx.getImageData(0, 0, 1, 1).data
return [r / 255, g / 255, b / 255]
}
}
type Panel = { texture: WebGLTexture | null; aspect: number; fade: number }
export function GlassLensCarousel({
items,
brand,
panelHeight = 0.62,
gap = 12,
radius = 6,
tint = "#009dff",
focusable = true,
closeLabel = "Close",
className,
...props
}: GlassLensCarouselProps) {
const canvasRef = React.useRef(null)
const [active, setActive] = React.useState(0)
const [focused, setFocused] = React.useState(null)
const [reduced, setReduced] = React.useState(false)
const [supported, setSupported] = React.useState(true)
// The frame loop reads these. They are refs so that changing a label or a
// tint does not tear the loop down and drop the row back to its entry state.
const settings = React.useRef({ panelHeight, gap, radius, tint, focusable })
settings.current = { panelHeight, gap, radius, tint, focusable }
const focusRef = React.useRef(null)
focusRef.current = focused
/** Populated by the render loop so keyboard input drives the same travel the
wheel does. */
const step = React.useRef<(by: number) => void>(() => {})
const count = items.length
// The loop owns the textures, so it rebuilds when the pictures change - and
// must not when only a caption does.
const sources = items.map((item) => item.image).join(" ")
React.useEffect(() => {
const query = window.matchMedia("(prefers-reduced-motion: reduce)")
const read = () => setReduced(query.matches)
read()
query.addEventListener("change", read)
return () => query.removeEventListener("change", read)
}, [])
React.useEffect(() => {
const canvas = canvasRef.current
if (!canvas || !count) return
const gl = canvas.getContext("webgl2", { alpha: false, antialias: false })
if (!gl) {
setSupported(false)
return
}
const readColor = colorReader()
const panelProgram = build(gl, PANEL_VERT, PANEL_FRAG)
const lensProgram = build(gl, LENS_VERT, LENS_FRAG)
if (!panelProgram || !lensProgram) return
const panelU = uniforms(gl, panelProgram)
const lensU = uniforms(gl, lensProgram)
const quad = gl.createVertexArray()
gl.bindVertexArray(quad)
const buffer = gl.createBuffer()
gl.bindBuffer(gl.ARRAY_BUFFER, buffer)
gl.bufferData(
gl.ARRAY_BUFFER,
new Float32Array([0, 0, 1, 0, 0, 1, 0, 1, 1, 0, 1, 1]),
gl.STATIC_DRAW
)
gl.enableVertexAttribArray(0)
gl.vertexAttribPointer(0, 2, gl.FLOAT, false, 0, 0)
// The strip is rendered here at device resolution. Allocating this in CSS
// pixels and letting the optic magnify it is the difference between a clear
// element and a soft one.
const target = gl.createFramebuffer()
const rowTexture = gl.createTexture()
gl.bindTexture(gl.TEXTURE_2D, rowTexture)
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, target)
gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, rowTexture, 0)
gl.bindFramebuffer(gl.FRAMEBUFFER, null)
const panels: Panel[] = items.map(() => ({ texture: null, aspect: 1.5, fade: 0 }))
const images = items.map((item, i) => {
const image = new Image()
image.crossOrigin = "anonymous"
image.decoding = "async"
image.onload = () => {
const texture = gl.createTexture()
gl.bindTexture(gl.TEXTURE_2D, texture)
gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, image)
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)
gl.generateMipmap(gl.TEXTURE_2D)
panels[i].texture = texture
panels[i].aspect = image.naturalWidth / Math.max(image.naturalHeight, 1)
}
image.src = item.image
return image
})
// --- state ------------------------------------------------------------
let width = 0
let height = 0
let scroll = 0
let goal = 0
let velocity = 0
let energy = 0 // smoothed scroll activity, 0..1
let lastInput = 0
let snapped = true
let entry = 0
let focus = 0
let focusIndex = 0
let clock = 0
let previous = 0
let ticks = 0
let frame = 0
let background: [number, number, number] = [0, 0, 0]
let tintRgb: [number, number, number] = [0, 0.6, 1]
const widths = new Float32Array(count)
const centers = new Float32Array(count)
const screenX = new Float32Array(count)
let total = 1
let panelPx = 1
/** Each width derives from its own source aspect, so nothing is cropped. */
const measure = () => {
panelPx = height * settings.current.panelHeight
let x = 0
for (let i = 0; i < count; i++) {
widths[i] = panelPx * panels[i].aspect
centers[i] = x + widths[i] / 2
x += widths[i] + settings.current.gap
}
total = Math.max(x, 1)
}
/** Strip offset that places a given panel at centre, resolved along whichever
direction round the cycle is shorter, so settling never unwinds the whole
sequence. */
const centerFor = (i: number, from: number) =>
centers[i] + Math.round((from - centers[i]) / total) * total
const nearest = (from: number) => {
let best = 0
let bestGap = Infinity
for (let i = 0; i < count; i++) {
const distance = Math.abs(centerFor(i, from) - from)
if (distance < bestGap) {
bestGap = distance
best = i
}
}
return best
}
const resize = () => {
const w = canvas.clientWidth
const h = canvas.clientHeight
if (!w || !h) return
const dpr = Math.min(window.devicePixelRatio || 1, 2)
width = w
height = h
canvas.width = Math.round(w * dpr)
canvas.height = Math.round(h * dpr)
gl.bindTexture(gl.TEXTURE_2D, rowTexture)
gl.texImage2D(
gl.TEXTURE_2D, 0, gl.RGBA, canvas.width, canvas.height, 0,
gl.RGBA, gl.UNSIGNED_BYTE, null
)
measure()
}
resize()
const observer = new ResizeObserver(resize)
observer.observe(canvas)
// --- input ------------------------------------------------------------
const push = (delta: number) => {
goal += delta
lastInput = performance.now()
snapped = false
}
step.current = (by: number) => {
if (focusRef.current !== null) return
const from = nearest(goal)
const next = ((from + by) % count + count) % count
goal = centerFor(next, goal)
lastInput = performance.now()
snapped = true
velocity = 0
}
const onWheel = (event: WheelEvent) => {
if (focusRef.current !== null) return
const delta =
Math.abs(event.deltaX) > Math.abs(event.deltaY) ? event.deltaX : event.deltaY
event.preventDefault()
push(delta * WHEEL)
velocity = 0
}
canvas.addEventListener("wheel", onWheel, { passive: false })
let dragFrom: number | null = null
let dragTravel = 0
let dragLast = 0
let dragStep = 0
let dragging = false
const onDown = (event: PointerEvent) => {
if (focusRef.current !== null) return
dragFrom = event.clientX
dragTravel = 0
dragStep = 0
dragging = true
dragLast = performance.now()
velocity = 0
canvas.setPointerCapture(event.pointerId)
}
const onMove = (event: PointerEvent) => {
if (dragFrom === null) return
// Touch input tracks one-to-one; pointer input carries the weighted rate.
const travel = dragFrom - event.clientX
dragStep = travel * (event.pointerType === "touch" ? 1 : DRAG)
dragTravel += Math.abs(travel)
dragFrom = event.clientX
dragLast = performance.now()
push(dragStep)
}
const onUp = (event: PointerEvent) => {
if (dragFrom === null) return
const slop = event.pointerType === "touch" ? 12 : CLICK_SLOP
const wasClick = dragTravel < slop
dragFrom = null
dragging = false
// A pointer at rest before release was positioning the strip rather than
// launching it, so momentum is granted only to movement still in progress.
if (!wasClick && performance.now() - dragLast < 90) velocity = dragStep
if (wasClick && settings.current.focusable) {
const hit = pick(event.clientX)
if (hit >= 0) {
goal = centerFor(hit, goal)
setFocused(hit)
}
}
}
/** Identifies the panel beneath a client x-coordinate. Positions are taken
from the frame currently on screen, so this queries what is displayed
rather than recomputing the layout. */
const pick = (clientX: number) => {
const x = clientX - canvas.getBoundingClientRect().left - width / 2
const scale = 1 - 0.25 * energy
for (let i = 0; i < count; i++) {
if (Math.abs(x - screenX[i]) <= (widths[i] * scale) / 2) return i
}
return -1
}
canvas.addEventListener("pointerdown", onDown)
canvas.addEventListener("pointermove", onMove)
canvas.addEventListener("pointerup", onUp)
canvas.addEventListener("pointercancel", onUp)
// --- frame ------------------------------------------------------------
const draw = (now: number) => {
frame = requestAnimationFrame(draw)
if (!width || !height) return
const dt = previous ? Math.min((now - previous) / 1000, 1 / 20) : 0
previous = now
clock += dt
measure()
if (ticks++ % THEME_EVERY === 0) {
background = readColor(getComputedStyle(canvas).backgroundColor)
tintRgb = readColor(settings.current.tint)
}
// Runs a single time on an independent clock, and only once there is
// artwork to show - the sequence is wasted on empty rectangles.
if (panels.some((panel) => panel.texture)) {
entry = reduced ? 1 : Math.min(1, entry + dt / ENTRY_SECONDS)
}
// The expanded view supersedes everything else: input is suspended, the
// chosen panel holds position and enlarges, the rest withdraw.
const wanted = focusRef.current
if (wanted !== null) focusIndex = wanted
const focusGoal = wanted === null ? 0 : 1
focus = reduced ? focusGoal : focus + (focusGoal - focus) * FOCUS_EASE
if (Math.abs(focus - focusGoal) < 0.002) focus = focusGoal
if (Math.abs(velocity) > 0.4) {
goal += velocity
velocity *= FRICTION
lastInput = now
snapped = false
} else velocity = 0
// Settling is triggered by elapsed quiet rather than by remaining
// distance. A slow scroll and a fast flick both fall silent identically,
// whereas any speed threshold would treat them differently.
if (!snapped && !dragging && now - lastInput > SNAP_IDLE && !velocity) {
goal = centerFor(nearest(goal), goal)
snapped = true
}
const before = scroll
const ease = dragging ? DRAG_EASE : snapped ? SNAP_EASE : EASE
scroll += (goal - scroll) * (reduced ? 1 : ease)
const speed = Math.abs(scroll - before)
const want = clamp(speed / SHRINK_MAX, 0, 1)
energy += (want - energy) * (want > energy ? SHRINK_ATTACK : SHRINK_DECAY)
const near = nearest(scroll)
setActive((prev) => (prev === near ? prev : near))
// --- pass one: the row, into a texture -----------------------------
gl.bindFramebuffer(gl.FRAMEBUFFER, target)
gl.viewport(0, 0, canvas.width, canvas.height)
gl.clearColor(background[0], background[1], background[2], 1)
gl.clear(gl.COLOR_BUFFER_BIT)
gl.useProgram(panelProgram)
gl.bindVertexArray(quad)
gl.uniform2f(panelU("uRes"), width, height)
gl.uniform3fv(panelU("uBg"), background)
gl.uniform1i(panelU("uTex"), 0)
gl.uniform1f(panelU("uRadius"), settings.current.radius)
gl.activeTexture(gl.TEXTURE0)
const shrink = 1 - 0.25 * energy
const half = width / 2
const copies = Math.ceil(width / total) + 2
for (let i = 0; i < count; i++) {
const panel = panels[i]
panel.fade = Math.min(1, panel.fade + (panel.texture ? dt * 5 : 0))
screenX[i] = Infinity
// Folded into a window centred on the stage, then stepped outward on
// both sides - the sequence has no terminus, so a panel can appear twice.
const x = (((centers[i] - scroll) % total) + total * 1.5) % total - total / 2
const rank = Math.abs(i - near)
const grow = outQuint(
clamp(entry * (1 + ENTRY_STAGGER * count) - rank * ENTRY_STAGGER, 0, 1)
)
const scale = lerp(ENTRY_START, 1, grow) * shrink
let w = widths[i] * scale
let h = panelPx * scale
let y = (1 - grow) * height * 0.55
if (focus > 0) {
if (i === focusIndex) {
w *= 1 + FOCUS_GROW * focus
h *= 1 + FOCUS_GROW * focus
} else {
// Offset from the centre outward: adjacent panels leave first, the
// extremes last.
const fall = outQuint(
clamp(
focus * (1 + FOCUS_STAGGER * count) -
Math.abs(i - focusIndex) * FOCUS_STAGGER,
0,
1
)
)
y -= fall * height * FOCUS_DROP
}
}
for (let c = 0; c < copies; c++) {
const px = x + (c - Math.floor(copies / 2)) * total
if (px < -half - w || px > half + w) continue
if (Math.abs(px) < Math.abs(screenX[i])) screenX[i] = px
if (!panel.texture) continue
gl.bindTexture(gl.TEXTURE_2D, panel.texture)
gl.uniform4f(panelU("uRect"), px, y, w, h)
gl.uniform1f(panelU("uFade"), panel.fade)
gl.drawArrays(gl.TRIANGLES, 0, 6)
}
}
// --- pass two: read it back through the glass ----------------------
gl.bindFramebuffer(gl.FRAMEBUFFER, null)
gl.viewport(0, 0, canvas.width, canvas.height)
gl.useProgram(lensProgram)
gl.bindVertexArray(quad)
gl.activeTexture(gl.TEXTURE0)
gl.bindTexture(gl.TEXTURE_2D, rowTexture)
gl.uniform1i(lensU("uTex"), 0)
gl.uniform1f(lensU("uAspect"), width / height)
gl.uniform1f(lensU("uTime"), reduced ? 0 : clock)
gl.uniform1f(lensU("uStrength"), outQuint(entry) * (1 - focus))
gl.uniform3fv(lensU("uTint"), tintRgb)
gl.drawArrays(gl.TRIANGLES, 0, 6)
}
frame = requestAnimationFrame(draw)
return () => {
cancelAnimationFrame(frame)
observer.disconnect()
canvas.removeEventListener("wheel", onWheel)
canvas.removeEventListener("pointerdown", onDown)
canvas.removeEventListener("pointermove", onMove)
canvas.removeEventListener("pointerup", onUp)
canvas.removeEventListener("pointercancel", onUp)
for (const image of images) image.onload = null
for (const panel of panels) if (panel.texture) gl.deleteTexture(panel.texture)
gl.deleteTexture(rowTexture)
gl.deleteFramebuffer(target)
gl.deleteBuffer(buffer)
gl.deleteVertexArray(quad)
gl.deleteProgram(panelProgram)
gl.deleteProgram(lensProgram)
}
// `sources` stands in for `items` - see the note beside it.
// eslint-disable-next-line react-hooks/exhaustive-deps
}, [sources, count, reduced])
const item = items[active]
const open = focused !== null
// No WebGL2 - a blank rectangle is the one outcome worse than no effect. The
// row without its glass is still the row: a native snap scroller of the same
// pictures, in the same order.
if (!supported) {
return (