Add a wave propagation ripple effect to the website navbar (#4150)

* WIP: Website navbar ripple

* Fix performance and other bugs

* Make the navbar ripple's active button explicitly inert
This commit is contained in:
Keavon Chambers
2026-06-08 23:15:12 -07:00
committed by GitHub
parent b4e04e616a
commit 02a40a860f
3 changed files with 285 additions and 71 deletions

View File

@@ -227,23 +227,34 @@ body > .page {
.ripple {
display: block;
background: none;
// Covers up content that extends up underneath the header
fill: white;
stroke: currentColor;
--ripple-height: 16px;
// Total SVG height splits into space above the baseline (for raised bumps and wave crests) and space below (for wave troughs that dip into the page body)
--ripple-height: 32px;
--ripple-baseline-from-top: 16px;
--ripple-taper-half-width: 40px;
height: var(--ripple-height);
margin-top: calc(-1 * var(--ripple-height) + var(--border-thickness));
margin-bottom: calc(-1 * var(--border-thickness));
stroke-width: var(--border-thickness);
margin-top: calc(-1 * var(--ripple-baseline-from-top) + var(--border-thickness));
margin-bottom: calc(-1 * (var(--ripple-height) - var(--ripple-baseline-from-top)) - var(--border-thickness));
// Allow taper polygons (apex at +/- 40px) and wave crests/troughs to spill outside the SVG box; the path's off-screen fill corners are still drawn within bounds since the line/mask are split
overflow: visible;
clip-path: inset(-100px calc(-1 * var(--ripple-taper-half-width)) -100px calc(-1 * var(--ripple-taper-half-width)));
pointer-events: none;
&::before,
&::after {
content: none;
.ripple-mask {
// Covers up content that extends up underneath the header
fill: white;
stroke: none;
}
}
hr {
background: none;
.ripple-line {
fill: none;
stroke: currentColor;
stroke-width: var(--border-thickness);
}
polygon {
fill: currentColor;
stroke: none;
}
}
@media screen and (max-width: 1400px) {

View File

@@ -1,24 +1,61 @@
const NAV_BUTTON_INITIAL_FONT_SIZE = 28; // Keep up to date with the initial `--nav-font-size` in base.scss
const RIPPLE_ANIMATION_MILLISECONDS = 100;
const RIPPLE_WIDTH = 100;
const HANDLE_STRETCH = 0.4;
// Keep up to date with the initial `--nav-font-size` in base.scss
const NAV_BUTTON_INITIAL_FONT_SIZE = 28;
// Local "lift" bump under each hovered/active button (gravitational attractor that pulls the surface up)
const BUMP_RAISE_MILLISECONDS = 120;
const BUMP_WIDTH = 100;
// Propagating wave pulse emitted when a lifted button drops back down (the splash from removing your finger from the water)
const WAVE_SPEED_PX_PER_SECOND = 1000;
const WAVE_PACKET_SIGMA = 200;
const WAVE_WAVELENGTH = 300;
const WAVE_AMPLITUDE = 10;
const WAVE_ATTENUATION_LENGTH = 500;
const WAVE_RAMP_UP_MILLISECONDS = 80;
const WAVE_PRUNE_AMPLITUDE = 0.15;
const WAVE_SAMPLE_SPACING = 6;
// Wider-than-the-bump zone around each lifted button where a passing wave's contribution to the surface is locally damped, so the bump doesn't tilt or jiggle when waves pass through it
const WAVE_SUPPRESSION_HALF_WIDTH = 200;
let /** @type {NodeList | undefined} **/ navButtons;
let /** @type {Element | undefined} **/ rippleSvg;
let /** @type {Element | undefined} **/ ripplePath;
let /** @type {number | undefined} **/ fullRippleHeight;
let /** @type {Element | undefined} **/ rippleMaskPath;
let /** @type {Element | undefined} **/ rippleLinePath;
let /** @type {Element | undefined} **/ rippleTaperLeft;
let /** @type {Element | undefined} **/ rippleTaperRight;
let /** @type {number | undefined} **/ baselineFromTop;
let /** @type {number | undefined} **/ taperHalfWidth;
let /** @type {{ element: HTMLElement, goingUp: boolean, animationStartTime: number, animationEndTime: number }[]} **/ ripples;
let /** @type {number} **/ activeRippleIndex;
let /** @type {{ originX: number, startTime: number }[]} **/ wavePulses = [];
// Metrics derived from computed styles, cached here and refreshed only on resize (they shift across media-query breakpoints) rather than re-read every frame
let /** @type {number} **/ rippleStrokeWidth;
let /** @type {number} **/ mediaQueryScaleFactor;
// The in-flight animation frame, if any; used to guarantee a single render loop no matter how many pointer events arrive
let /** @type {number | undefined} **/ animationFrameId;
// Set by the resize handler, consumed by the next animation frame
let /** @type {boolean} **/ pendingResize = false;
window.addEventListener("DOMContentLoaded", initializeRipples);
function initializeRipples() {
window.addEventListener("resize", () => animate(true));
// Defer resize work to the next animation frame so rapid resize events coalesce into a single metrics refresh and redraw
window.addEventListener("resize", () => {
pendingResize = true;
requestAnimate();
});
navButtons = document.querySelectorAll("header nav a") || undefined;
navButtons = document.querySelectorAll("header nav a");
rippleSvg = document.querySelector("header .ripple") || undefined;
ripplePath = rippleSvg?.querySelector("path") || undefined;
fullRippleHeight = rippleSvg ? Number.parseInt(window.getComputedStyle(rippleSvg).height, 10) || undefined : undefined;
rippleMaskPath = rippleSvg?.querySelector(".ripple-mask") || undefined;
rippleLinePath = rippleSvg?.querySelector(".ripple-line") || undefined;
rippleTaperLeft = rippleSvg?.querySelector(".ripple-taper-left") || undefined;
rippleTaperRight = rippleSvg?.querySelector(".ripple-taper-right") || undefined;
refreshMetrics();
ripples = Array.from(navButtons)
.filter((x) => x instanceof HTMLElement)
@@ -43,11 +80,14 @@ function initializeRipples() {
return location.startsWith(link);
});
ripples.forEach((ripple) => {
ripples.forEach((ripple, index) => {
// The active page's button is permanently lifted and inert, so it gets no hover listeners
if (index === activeRippleIndex) return;
const updateTimings = (/** @type {boolean} **/ goingUp) => {
const start = ripple.animationStartTime;
const now = Date.now();
const stop = ripple.animationStartTime + RIPPLE_ANIMATION_MILLISECONDS;
const stop = ripple.animationStartTime + BUMP_RAISE_MILLISECONDS;
const elapsed = now - start;
const remaining = stop - now;
@@ -55,9 +95,11 @@ function initializeRipples() {
ripple.goingUp = goingUp;
// Encode the potential reversing of direction via the animation start and end times
ripple.animationStartTime = now < stop ? now - remaining : now;
ripple.animationEndTime = now < stop ? now + elapsed : now + RIPPLE_ANIMATION_MILLISECONDS;
ripple.animationEndTime = now < stop ? now + elapsed : now + BUMP_RAISE_MILLISECONDS;
animate();
// Only the drop emits a ripple, like releasing a finger from the water surface; the lift only deforms it locally
if (!goingUp) emitWavePulse(ripple);
requestAnimate();
};
ripple.element.addEventListener("pointerenter", () => updateTimings(true));
@@ -65,71 +107,230 @@ function initializeRipples() {
});
if (activeRippleIndex >= 0) {
ripples[activeRippleIndex] = {
...ripples[activeRippleIndex],
goingUp: true,
// Set to non-zero, but very old times (1ms after epoch), so the math works out as if the animation has already completed
animationStartTime: 1,
animationEndTime: 1 + RIPPLE_ANIMATION_MILLISECONDS,
};
// Initialize the active button lifted; the very old times (1ms after epoch) make the math treat its lift as already complete
const active = ripples[activeRippleIndex];
active.goingUp = true;
active.animationStartTime = 1;
active.animationEndTime = 1 + BUMP_RAISE_MILLISECONDS;
}
setRipples();
// Web fonts can load after this initial layout and reflow the nav buttons, leaving the active page's static bump offset; redraw once they're ready
document.fonts?.ready.then(setRipples);
}
function animate(forceRefresh = false) {
const FUZZ_MILLISECONDS = 100;
const animateThisFrame = ripples.some((ripple) => ripple.animationStartTime > 0 && ripple.animationEndTime > 0 && Date.now() <= ripple.animationEndTime + FUZZ_MILLISECONDS);
function emitWavePulse(/** @type {{ element: HTMLElement }} **/ ripple) {
if (!rippleSvg) return;
if (animateThisFrame || forceRefresh) {
const buttonRect = ripple.element.getBoundingClientRect();
const svgRect = rippleSvg.getBoundingClientRect();
const originX = buttonRect.left - svgRect.left + buttonRect.width / 2;
wavePulses.push({
originX,
startTime: Date.now(),
});
}
function refreshMetrics() {
if (!rippleSvg || !navButtons || !(navButtons[0] instanceof HTMLElement)) return;
const svgStyle = window.getComputedStyle(rippleSvg);
baselineFromTop = Number.parseInt(svgStyle.getPropertyValue("--ripple-baseline-from-top"), 10) || undefined;
taperHalfWidth = Number.parseInt(svgStyle.getPropertyValue("--ripple-taper-half-width"), 10) || undefined;
rippleStrokeWidth = Number.parseInt(svgStyle.getPropertyValue("--border-thickness"), 10);
const navButtonFontSize = Number.parseInt(window.getComputedStyle(navButtons[0]).fontSize, 10) || NAV_BUTTON_INITIAL_FONT_SIZE;
mediaQueryScaleFactor = navButtonFontSize / NAV_BUTTON_INITIAL_FONT_SIZE;
}
// Schedule the render loop, but only if it isn't already running, so a burst of pointer events can't stack up redundant concurrent loops
function requestAnimate() {
if (animationFrameId !== undefined) return;
animationFrameId = window.requestAnimationFrame(animationTick);
}
function animationTick() {
animationFrameId = undefined;
// A resize since the last frame may have changed the cached metrics; refresh them here (once) rather than on every resize event
if (pendingResize) refreshMetrics();
const now = Date.now();
// Drop pulses whose amplitude has decayed below the visible threshold
wavePulses = wavePulses.filter((pulse) => {
const traveled = (WAVE_SPEED_PX_PER_SECOND * mediaQueryScaleFactor * (now - pulse.startTime)) / 1000;
return Math.exp(-traveled / (WAVE_ATTENUATION_LENGTH * mediaQueryScaleFactor)) > WAVE_PRUNE_AMPLITUDE / WAVE_AMPLITUDE;
});
const FUZZ_MILLISECONDS = 100;
const bumpsAnimating = ripples.some((ripple) => ripple.animationStartTime > 0 && ripple.animationEndTime > 0 && now <= ripple.animationEndTime + FUZZ_MILLISECONDS);
const wavesActive = wavePulses.length > 0;
// Keep looping while anything is animating; a lone pending resize just needs the single redraw below
if (bumpsAnimating || wavesActive || pendingResize) {
pendingResize = false;
setRipples();
window.requestAnimationFrame(() => animate());
if (bumpsAnimating || wavesActive) requestAnimate();
}
}
function setRipples() {
const lerp = (/** @type {number} **/ a, /** @type {number} **/ b, /** @type {number} **/ t) => a + (b - a) * t;
const ease = (/** @type {number} **/ x) => 1 - (1 - x) * (1 - x);
const clamp01 = (/** @type {number} **/ x) => Math.min(Math.max(x, 0), 1);
if (!rippleSvg || !ripplePath || !navButtons || !fullRippleHeight || !(navButtons[0] instanceof HTMLElement)) return;
if (!rippleSvg || !rippleMaskPath || !rippleLinePath) return;
if (!rippleTaperLeft || !rippleTaperRight) return;
if (!navButtons || !baselineFromTop || !taperHalfWidth) return;
if (!(navButtons[0] instanceof HTMLElement)) return;
const now = Date.now();
const rippleSvgRect = rippleSvg.getBoundingClientRect();
const rippleStrokeWidth = Number.parseInt(window.getComputedStyle(ripplePath).getPropertyValue("--border-thickness"), 10);
const navButtonFontSize = Number.parseInt(window.getComputedStyle(navButtons[0]).fontSize, 10) || NAV_BUTTON_INITIAL_FONT_SIZE;
const mediaQueryScaleFactor = navButtonFontSize / NAV_BUTTON_INITIAL_FONT_SIZE;
// Baseline centerline: --ripple-baseline-from-top marks where the bottom edge of the baseline stroke sits, so the centerline is half a stroke above
const baselineY = baselineFromTop - rippleStrokeWidth / 2;
const toplineY = rippleStrokeWidth / 2;
const maxBumpHeight = baselineY - toplineY;
// Position of bottom centerline to top centerline
const rippleBaselineCenterline = fullRippleHeight - rippleStrokeWidth / 2;
const rippleToplineCenterline = rippleStrokeWidth / 2;
// Snapshot per-button lift state for this frame: a "gravity" bump that pulls the surface up linearly
const bumpHalfWidth = (BUMP_WIDTH / 2) * mediaQueryScaleFactor;
const suppressionHalfWidth = WAVE_SUPPRESSION_HALF_WIDTH * mediaQueryScaleFactor;
const bumps = ripples
.map((ripple) => {
if (ripple.animationStartTime === 0 && ripple.animationEndTime === 0) return null;
let path = `M -16,${rippleBaselineCenterline - 16} L 0,${rippleBaselineCenterline} `;
const elapsed = now - ripple.animationStartTime;
const duration = ripple.animationEndTime - ripple.animationStartTime;
const t = ease(clamp01(elapsed / duration));
const liftFraction = clamp01(ripple.goingUp ? t : 1 - t);
if (liftFraction <= 0) return null;
ripples.forEach((ripple) => {
if (ripple.animationStartTime === 0 || ripple.animationEndTime === 0) return;
const buttonRect = ripple.element.getBoundingClientRect();
const centerX = buttonRect.left - rippleSvgRect.left + buttonRect.width / 2;
const elapsed = Date.now() - ripple.animationStartTime;
const duration = ripple.animationEndTime - ripple.animationStartTime;
const t = ease(clamp01(elapsed / duration));
return { centerX, height: maxBumpHeight * liftFraction * mediaQueryScaleFactor, halfWidth: bumpHalfWidth, liftFraction, suppressionHalfWidth };
})
.filter((bump) => bump !== null);
const bumpCrestRaiseFactor = (ripple.goingUp ? t : 1 - t) * mediaQueryScaleFactor;
const bumpCrest = lerp(rippleToplineCenterline, rippleBaselineCenterline, bumpCrestRaiseFactor);
const bumpCrestDelta = bumpCrest - rippleStrokeWidth / 2;
const buttonRect = ripple.element.getBoundingClientRect();
const buttonCenter = buttonRect.width / 2;
const rippleCenter = (RIPPLE_WIDTH / 2) * mediaQueryScaleFactor;
const rippleOffset = rippleCenter - buttonCenter;
const rippleStartX = buttonRect.left - rippleSvgRect.left - rippleOffset;
const handleRadius = rippleCenter * HANDLE_STRETCH;
path += `L ${rippleStartX},${rippleBaselineCenterline} `;
path += `c ${handleRadius},0 ${rippleCenter - handleRadius},${-bumpCrestDelta} ${rippleCenter},${-bumpCrestDelta} `;
path += `s ${rippleCenter - handleRadius},${bumpCrestDelta} ${rippleCenter},${bumpCrestDelta} `;
// Snapshot per-pulse propagation state for this frame
const pulses = wavePulses.map((pulse) => {
const ageMs = now - pulse.startTime;
const ageSeconds = ageMs / 1000;
// Speed and attenuation distance scale with the UI so the wave looks identical (just smaller) when media queries shrink the navbar
const traveled = WAVE_SPEED_PX_PER_SECOND * mediaQueryScaleFactor * ageSeconds;
const rampFactor = clamp01(ageMs / WAVE_RAMP_UP_MILLISECONDS);
const distanceAttenuation = Math.exp(-traveled / (WAVE_ATTENUATION_LENGTH * mediaQueryScaleFactor));
const sigma = WAVE_PACKET_SIGMA * mediaQueryScaleFactor;
const wavelength = WAVE_WAVELENGTH * mediaQueryScaleFactor;
const amplitude = WAVE_AMPLITUDE * mediaQueryScaleFactor * rampFactor * distanceAttenuation;
return { originX: pulse.originX, traveled, sigma, wavelength, amplitude };
});
path += `L ${rippleSvgRect.width + 16},${rippleBaselineCenterline} L${rippleSvgRect.width + 16},${rippleBaselineCenterline - 16}`;
// Sample the surface: the lift bump adds directly while the wave is damped within a vicinity around each lifted button to avoid jiggling the bump
const sampleSpacing = WAVE_SAMPLE_SPACING * mediaQueryScaleFactor;
const numSamples = Math.max(2, Math.ceil(rippleSvgRect.width / sampleSpacing) + 1);
const samples = new Array(numSamples);
for (let i = 0; i < numSamples; i++) {
const x = (i / (numSamples - 1)) * rippleSvgRect.width;
ripplePath.setAttribute("d", path);
// The local lift bump adds directly to the surface height, while each lifted button damps passing waves within a wider zone (scaled by how lifted it is) so its bump doesn't jiggle
let liftHeight = 0;
let waveSuppression = 0;
for (let j = 0; j < bumps.length; j++) {
const bump = bumps[j];
const dist = x - bump.centerX;
if (Math.abs(dist) < bump.halfWidth) {
liftHeight += bump.height * Math.cos((Math.PI * dist) / (2 * bump.halfWidth)) ** 2;
}
if (Math.abs(dist) < bump.suppressionHalfWidth) {
waveSuppression += bump.liftFraction * Math.cos((Math.PI * dist) / (2 * bump.suppressionHalfWidth)) ** 2;
}
}
waveSuppression = Math.min(1, waveSuppression);
// Each pulse contributes two d'Alembert halves moving in opposite directions
let waveHeight = 0;
for (let j = 0; j < pulses.length; j++) {
const pulse = pulses[j];
waveHeight += halfPulseContribution(x, pulse.originX - pulse.traveled, pulse);
waveHeight += halfPulseContribution(x, pulse.originX + pulse.traveled, pulse);
}
const displacement = liftHeight + waveHeight * (1 - waveSuppression);
samples[i] = { x, y: baselineY - displacement };
}
const waveCurve = buildSmoothCurve(samples);
const cornerY = baselineY - 16;
const leftCornerX = -16;
const rightCornerX = rippleSvgRect.width + 16;
const last = samples[samples.length - 1];
// Mask: closed region above the wave that hides navbar content under the SVG. Includes off-screen corners for a clean fill closure.
const maskPath = `M ${leftCornerX},${cornerY} L ${samples[0].x.toFixed(2)},${samples[0].y.toFixed(2)} ${waveCurve} L ${rightCornerX},${last.y.toFixed(2)} L ${rightCornerX},${cornerY}`;
rippleMaskPath.setAttribute("d", maskPath);
// Visible wave line: just the curve, no off-screen extensions, so its stroke never appears outside the SVG bounds
const linePath = `M ${samples[0].x.toFixed(2)},${samples[0].y.toFixed(2)} ${waveCurve}`;
rippleLinePath.setAttribute("d", linePath);
// Tapered end caps: apex sits at the baseline's bottom edge so the bottom stays flat while the top slopes down to meet it, matching the original CSS-border triangles
const halfStroke = rippleStrokeWidth / 2;
const apexY = baselineY + halfStroke;
const leftApexX = -taperHalfWidth;
const rightApexX = rippleSvgRect.width + taperHalfWidth;
const wideRightX = rippleSvgRect.width.toFixed(2);
const leftPoints = `${leftApexX},${apexY} 0,${(samples[0].y - halfStroke).toFixed(2)} 0,${(samples[0].y + halfStroke).toFixed(2)}`;
const rightPoints = `${rightApexX},${apexY} ${wideRightX},${(last.y - halfStroke).toFixed(2)} ${wideRightX},${(last.y + halfStroke).toFixed(2)}`;
rippleTaperLeft.setAttribute("points", leftPoints);
rippleTaperRight.setAttribute("points", rightPoints);
}
// One d'Alembert half-pulse's contribution to the surface height at position `x`, as a Gaussian-windowed cosine wave packet
function halfPulseContribution(/** @type {number} **/ x, /** @type {number} **/ center, /** @type {{ sigma: number, wavelength: number, amplitude: number }} **/ pulse) {
const dist = x - center;
const distNorm = dist / pulse.sigma;
// The Gaussian envelope is negligible past 4 sigma, so skip the transcendentals out there
if (Math.abs(distNorm) > 4) return 0;
const envelope = Math.exp(-distNorm * distNorm);
const oscillation = Math.cos((2 * Math.PI * dist) / pulse.wavelength);
return 0.5 * pulse.amplitude * envelope * oscillation;
}
function buildSmoothCurve(/** @type {{ x: number, y: number }[]} **/ samples) {
const get = (/** @type {number} **/ index) => {
if (index < 0) {
// Reflect first segment to derive a virtual point with matching tangent
const a = samples[0];
const b = samples[1];
return { x: 2 * a.x - b.x, y: 2 * a.y - b.y };
}
if (index >= samples.length) {
const a = samples[samples.length - 1];
const b = samples[samples.length - 2];
return { x: 2 * a.x - b.x, y: 2 * a.y - b.y };
}
return samples[index];
};
// Catmull-Rom-to-cubic-Bezier across the sample chain for a smooth surface curve
return samples
.slice(0, -1)
.map((p1, i) => {
const p0 = get(i - 1);
const p2 = samples[i + 1];
const p3 = get(i + 2);
const cp1x = p1.x + (p2.x - p0.x) / 6;
const cp1y = p1.y + (p2.y - p0.y) / 6;
const cp2x = p2.x - (p3.x - p1.x) / 6;
const cp2y = p2.y - (p3.y - p1.y) / 6;
return `C ${cp1x.toFixed(2)},${cp1y.toFixed(2)} ${cp2x.toFixed(2)},${cp2y.toFixed(2)} ${p2.x.toFixed(2)},${p2.y.toFixed(2)} `;
})
.join("");
}

View File

@@ -124,9 +124,11 @@
</div>
</nav>
<svg class="ripple" xmlns="http://www.w3.org/2000/svg">
<path d="M 0,15 l 10000,0" />
<path class="ripple-mask" d="M 0,15 l 10000,0" />
<path class="ripple-line" d="M 0,15 l 10000,0" />
<polygon class="ripple-taper-left" />
<polygon class="ripple-taper-right" />
</svg>
<hr />
</header>
<main>
{# This is a comment. It exists to prevent the {%- -%} on the lines below from removing the line break between `<main>` and the `content` block #}