ParallaxLayers

npx motionfoundry add parallax-layers

1import { ParallaxLayers } from "@motionfoundry/ui";2 3export function Example() {4  return (5    <ParallaxLayers />6  );7}

1"use client";2 3import * as React from "react";4import styles from "../styles/parallax-layers.module.css";5 6interface SmoothScrollState {7  /** Current scrollTop of the viewport in px */8  scroll: number;9  /** Maximum scrollTop in px */10  limit: number;11  /** scroll / limit, 0..1 */12  progress: number;13  /** Signed scroll velocity in px per 60fps frame */14  velocity: number;15}16 17interface SmoothScrollOptions {18  lerp: number;19  wheelMultiplier: number;20  smooth: boolean;21  onScroll?: (state: SmoothScrollState) => void;22}23 24const clamp = (v: number, min: number, max: number) => Math.min(max, Math.max(min, v));25 26function usePrefersReducedMotion(): boolean {27  const [reduced, setReduced] = React.useState(false);28  React.useEffect(() => {29    const mq = window.matchMedia("(prefers-reduced-motion: reduce)");30    const update = () => setReduced(mq.matches);31    update();32    mq.addEventListener("change", update);33    return () => mq.removeEventListener("change", update);34  }, []);35  return reduced;36}37 38/** True when a nested scrollable element under the pointer can still scroll in the wheel direction. */39function nestedCanScroll(node: EventTarget | null, root: HTMLElement, dy: number): boolean {40  let el: Element | null = node instanceof Element ? node : null;41  while (el && el !== root) {42    if (el instanceof HTMLElement) {43      if (el.dataset.mfScrollPrevent !== undefined) return true;44      const overflowY = window.getComputedStyle(el).overflowY;45      if ((overflowY === "auto" || overflowY === "scroll") && el.scrollHeight > el.clientHeight + 1) {46        const canMove = dy < 0 ? el.scrollTop > 0 : el.scrollTop + el.clientHeight < el.scrollHeight - 1;47        if (canMove) return true;48      }49    }50    el = el.parentElement;51  }52  return false;53}54 55/**56 * Self-contained smooth scroller for an overflow container. Wheel input updates a target57 * position; a rAF loop eases the real scrollTop toward it (frame-rate independent lerp) and58 * stops once settled. Touch, keyboard and scrollbar drags stay native. At the top/bottom edge59 * wheel events are released so the page keeps scrolling.60 */61function useSmoothScroll(62  containerRef: React.RefObject<HTMLElement | null>,63  { lerp, wheelMultiplier, smooth, onScroll }: SmoothScrollOptions,64): React.RefObject<SmoothScrollState> {65  const stateRef = React.useRef<SmoothScrollState>({ scroll: 0, limit: 0, progress: 0, velocity: 0 });66  const callbackRef = React.useRef(onScroll);67  React.useEffect(() => {68    callbackRef.current = onScroll;69  }, [onScroll]);70 71  React.useEffect(() => {72    const el = containerRef.current;73    if (!el) return;74    const ease = clamp(Number.isFinite(lerp) ? lerp : 0.1, 0.01, 1);75    const multiplier = Number.isFinite(wheelMultiplier) ? wheelMultiplier : 1;76    let target = el.scrollTop;77    let current = target;78    let raf = 0;79    let lastTime = 0;80    let lastNative = el.scrollTop;81    let lastNativeTime = 0;82    let settleTimer: ReturnType<typeof setTimeout> | undefined;83 84    const getLimit = () => Math.max(0, el.scrollHeight - el.clientHeight);85 86    const emit = (velocity: number) => {87      const limit = getLimit();88      const scroll = clamp(el.scrollTop, 0, limit);89      lastNative = el.scrollTop;90      const s = stateRef.current;91      s.scroll = scroll;92      s.limit = limit;93      s.progress = limit > 0 ? scroll / limit : 0;94      s.velocity = velocity;95      callbackRef.current?.(s);96    };97 98    const tick = (time: number) => {99      const dt = lastTime ? Math.min(64, Math.max(1, time - lastTime)) : 16.667;100      lastTime = time;101      const limit = getLimit();102      target = clamp(target, 0, limit);103      if (Math.abs(el.scrollTop - current) > 2) {104        // Something else moved the viewport (scrollbar drag, keyboard, touch): hand control back.105        current = target = el.scrollTop;106        raf = 0;107        lastTime = 0;108        emit(0);109        return;110      }111      const prev = current;112      const frames = dt / 16.667;113      current += (target - current) * (1 - Math.pow(1 - ease, frames));114      if (Math.abs(target - current) < 0.35) current = target;115      el.scrollTop = current;116      emit((current - prev) / frames);117      if (current === target) {118        raf = 0;119        lastTime = 0;120        emit(0);121        return;122      }123      raf = requestAnimationFrame(tick);124    };125 126    const onWheel = (event: WheelEvent) => {127      if (event.ctrlKey || event.defaultPrevented) return;128      if (Math.abs(event.deltaX) > Math.abs(event.deltaY)) return;129      let dy = event.deltaY;130      if (event.deltaMode === 1) dy *= 16;131      else if (event.deltaMode === 2) dy *= el.clientHeight;132      dy *= multiplier;133      if (dy === 0 || nestedCanScroll(event.target, el, dy)) return;134      const limit = getLimit();135      if (!raf) current = target = el.scrollTop;136      // Release to native scrolling at the edges so the page is never trapped.137      if ((dy < 0 && target <= 0) || (dy > 0 && target >= limit - 0.5)) return;138      event.preventDefault();139      target = clamp(target + dy, 0, limit);140      if (!raf) {141        lastTime = 0;142        raf = requestAnimationFrame(tick);143      }144    };145 146    const onNativeScroll = () => {147      if (raf) return;148      const top = el.scrollTop;149      const delta = top - lastNative;150      if (delta === 0) return;151      const now = performance.now();152      const dt = lastNativeTime ? clamp(now - lastNativeTime, 8, 100) : 16.667;153      lastNativeTime = now;154      current = target = top;155      emit(delta / (dt / 16.667));156      if (settleTimer) clearTimeout(settleTimer);157      settleTimer = setTimeout(() => {158        lastNativeTime = 0;159        emit(0);160      }, 90);161    };162 163    if (smooth) el.addEventListener("wheel", onWheel, { passive: false });164    el.addEventListener("scroll", onNativeScroll, { passive: true });165    const ro = new ResizeObserver(() => emit(stateRef.current.velocity));166    ro.observe(el);167    if (el.firstElementChild) ro.observe(el.firstElementChild);168    emit(0);169 170    return () => {171      if (smooth) el.removeEventListener("wheel", onWheel);172      el.removeEventListener("scroll", onNativeScroll);173      ro.disconnect();174      if (raf) cancelAnimationFrame(raf);175      if (settleTimer) clearTimeout(settleTimer);176    };177  }, [containerRef, lerp, wheelMultiplier, smooth]);178 179  return stateRef;180}181 182export interface ParallaxLayersProps {183  /** Headline shown on the first screen */184  title?: string;185  /** Supporting line under the headline */186  subtitle?: string;187  /** Number of depth layers (2–5) */188  layers?: number;189  /** Multiplier for the speed difference between layers */190  depth?: number;191  /** Primary layer color */192  color1?: string;193  /** Secondary layer color */194  color2?: string;195  /** Tertiary layer color */196  color3?: string;197  /** Viewport height in px */198  height?: number;199  /** Viewport corner radius in px */200  borderRadius?: number;201  /** Interpolation factor per 60fps frame (0.05 = floaty, 0.3 = snappy) */202  lerp?: number;203  /** Multiplier applied to wheel / trackpad deltas */204  wheelMultiplier?: number;205  /** Enable smooth wheel scrolling (native scrolling when false or under reduced motion) */206  smooth?: boolean;207  /** Optional className merged onto the root */208  className?: string;209  /** Inline styles merged onto the root */210  style?: React.CSSProperties;211}212 213const rand = (n: number) => {214  const x = Math.sin(n * 9301 + 49297) * 233280;215  return x - Math.floor(x);216};217 218type LayerKind = "orb" | "ring" | "card" | "dot" | "spark";219 220/** Back-to-front layer recipes; speed is the fraction of the scroll distance a layer travels. */221const LAYERS: { kind: LayerKind; speed: number; count: number }[] = [222  { kind: "orb", speed: 0.12, count: 4 },223  { kind: "ring", speed: 0.32, count: 6 },224  { kind: "card", speed: 0.58, count: 6 },225  { kind: "dot", speed: 0.85, count: 14 },226  { kind: "spark", speed: 1.4, count: 9 },227];228 229const SCREENS = 3;230 231export function ParallaxLayers({232  title = "Depth in motion",233  subtitle = "Five planes drift at five speeds. Scroll inside to feel the space open up.",234  layers = 5,235  depth = 1,236  color1 = "#a78bfa",237  color2 = "#38bdf8",238  color3 = "#f472b6",239  height = 380,240  borderRadius = 20,241  lerp = 0.1,242  wheelMultiplier = 1,243  smooth = true,244  className = "",245  style,246}: ParallaxLayersProps) {247  const reduced = usePrefersReducedMotion();248  const rootRef = React.useRef<HTMLDivElement>(null);249  const viewportRef = React.useRef<HTMLDivElement>(null);250 251  const handleScroll = React.useCallback((state: SmoothScrollState) => {252    rootRef.current?.style.setProperty("--mf-pl-s", state.scroll.toFixed(2));253  }, []);254 255  useSmoothScroll(viewportRef, { lerp, wheelMultiplier, smooth: smooth && !reduced, onScroll: handleScroll });256 257  const count = clamp(Math.round(layers), 2, 5);258  const picked = Array.from({ length: count }, (_, i) => Math.round((i * (LAYERS.length - 1)) / (count - 1)));259  const colors = [color1, color2, color3];260  const safeDepth = Math.max(0, depth);261  const travel = height * (SCREENS - 1);262 263  const vars = {264    "--mf-pl-h": `${height}px`,265    "--mf-pl-r": `${borderRadius}px`,266    "--mf-pl-c1": color1,267    "--mf-pl-c2": color2,268    "--mf-pl-c3": color3,269    ...style,270  } as React.CSSProperties;271 272  return (273    <div ref={rootRef} style={vars} className={`${styles.root} ${className}`.trim()}>274      <div ref={viewportRef} className={styles.viewport} tabIndex={0} role="region" aria-label={title}>275        <div className={styles.content}>276          <div aria-hidden="true" className={styles.stage}>277            {picked.map((layerIndex, order) => {278              const layer = LAYERS[layerIndex];279              const speed = layer.speed * safeDepth;280              const span = height + travel * speed;281              return (282                <div283                  key={layer.kind}284                  className={`${styles.layer} ${styles[layer.kind]}`}285                  style={{ "--mf-pl-f": speed.toFixed(3), zIndex: order } as React.CSSProperties}286                >287                  {Array.from({ length: layer.count }, (_, i) => {288                    const seed = layerIndex * 97 + i * 13;289                    const top = ((i + rand(seed)) / layer.count) * span - height * 0.08;290                    const left = rand(seed + 1) * 92;291                    const size = 0.6 + rand(seed + 2) * 0.8;292                    return (293                      <span294                        key={i}295                        className={styles.item}296                        style={297                          {298                            top: `${top.toFixed(1)}px`,299                            left: `${left.toFixed(2)}%`,300                            "--mf-pl-size": size.toFixed(3),301                            "--mf-pl-c": colors[(i + layerIndex) % 3],302                            "--mf-pl-rot": `${Math.round(rand(seed + 3) * 40 - 20)}deg`,303                          } as React.CSSProperties304                        }305                      />306                    );307                  })}308                </div>309              );310            })}311          </div>312          <section className={styles.screen}>313            <span className={styles.kicker}>Parallax Layers</span>314            <h3 className={styles.title}>{title}</h3>315            <p className={styles.subtitle}>{subtitle}</p>316          </section>317          <section className={styles.screen}>318            <p className={styles.statement}>319              Back layers crawl.320              <br />321              <span className={styles.accentText}>Front layers race.</span>322            </p>323          </section>324          <section className={styles.screen}>325            <p className={styles.statement}>326              Your eye reads the difference327              <br />328              as <span className={styles.accentText}>distance</span>.329            </p>330          </section>331        </div>332      </div>333    </div>334  );335}