Move fullscreen wash to WebGPU

app/components/Player/Fullscreen/Background/Wash.vue

@@ -1,23 +1,30 @@
 <script setup lang="ts">
 import {
 	extractPalette,
-	fromOkLab,
-	toOkLab,
 	type AlbumPalette,
 } from "./palette"
+import { createCpuRenderer } from "./renderers/cpu"
+import { createWebGpuRenderer } from "./renderers/webgpu"
+import type { BackgroundFrame, BackgroundRenderer } from "./renderers/types"
 import { shapeBeatPulse } from "~/utils/beat"
 
 const props = defineProps<{ src: string; active: boolean }>()
 const ANIMATION_SPEED = 0.3
 const { beatEnergy } = usePlayer()
-const canvas = ref<HTMLCanvasElement | null>(null)
+const cpuCanvas = ref<HTMLCanvasElement | null>(null)
+const webGpuCanvas = ref<HTMLCanvasElement | null>(null)
 const palette = ref<AlbumPalette | null>(null)
+const backend = ref<"cpu" | "webgpu">("cpu")
 let frame = 0
 let startedAt = 0
 let lastFrameAt = 0
-let random = [0, 0]
+let random: [number, number] = [0, 0]
 let angleJitter = 0
 let flowParams: [number, number, number, number] = [5, 25, 0.75, -0.08]
+let cpuRenderer: BackgroundRenderer | null = null
+let webGpuRenderer: BackgroundRenderer | null = null
+let activeRenderer: BackgroundRenderer | null = null
+let disposed = false
 
 const fallback: AlbumPalette = { dominant: [30, 35, 55], accent: [105, 65, 45] }
 
@@ -26,23 +33,19 @@ function loadArtwork() {
 	image.crossOrigin = "anonymous"
 	image.onload = () => {
 		try {
-			setPalette(extractPalette(image))
+			palette.value = extractPalette(image)
 		} catch {
-			setPalette(fallback)
+			palette.value = fallback
 		}
 	}
 	image.onerror = () => {
-		setPalette(fallback)
+		palette.value = fallback
 	}
 	image.src = props.src
 }
 
-function setPalette(next: AlbumPalette) {
-	palette.value = next
-}
-
 function randomizeMotion() {
-	random = Array.from({ length: 2 }, () => Math.random() * Math.PI * 2)
+	random = [Math.random() * Math.PI * 2, Math.random() * Math.PI * 2]
 	angleJitter = (Math.random() - 0.5) * 0.3
 	flowParams = [
 		4.5 + Math.random(),
@@ -52,6 +55,101 @@ function randomizeMotion() {
 	]
 }
 
+function useCpuFallback() {
+	if (!cpuRenderer) return
+	activeRenderer = cpuRenderer
+	backend.value = "cpu"
+}
+
+async function initializeRenderers() {
+	const cpuElement = cpuCanvas.value
+	const gpuElement = webGpuCanvas.value
+	if (!cpuElement || !gpuElement) return
+	cpuRenderer = createCpuRenderer(cpuElement)
+	activeRenderer = cpuRenderer
+	if (!cpuRenderer) {
+		console.warn("[background renderer] 2D canvas is unavailable")
+		return
+	}
+
+	let rendererLost = false
+	const renderer = await createWebGpuRenderer(gpuElement, () => {
+		rendererLost = true
+		webGpuRenderer = null
+		console.warn("[background renderer] WebGPU device lost; using CPU")
+		useCpuFallback()
+	})
+	if (!renderer) return
+	if (disposed || rendererLost) {
+		renderer.dispose()
+		return
+	}
+	webGpuRenderer = renderer
+	activeRenderer = renderer
+	backend.value = "webgpu"
+	console.info("[background renderer] using WebGPU")
+}
+
+function makeFrame(now: number, canvas: HTMLCanvasElement): BackgroundFrame {
+	if (!startedAt) startedAt = now
+	const width = 224
+	const height = Math.max(
+		72,
+		Math.round(
+			(width * canvas.clientHeight) / Math.max(1, canvas.clientWidth),
+		),
+	)
+	return {
+		width,
+		height,
+		time: ((now - startedAt) / 1000) * ANIMATION_SPEED,
+		beat: shapeBeatPulse(beatEnergy.value),
+		random,
+		angleJitter,
+		flowParams,
+		palette: palette.value ?? fallback,
+	}
+}
+
+function draw(now: number) {
+	if (!props.active || disposed) return
+	if (now - lastFrameAt < 1000 / 24) {
+		frame = requestAnimationFrame(draw)
+		return
+	}
+	lastFrameAt = now
+	const canvas = backend.value === "webgpu" ? webGpuCanvas.value : cpuCanvas.value
+	if (canvas && activeRenderer) {
+		const renderFrame = makeFrame(now, canvas)
+		canvas.style.transform = `scale(${1.08 + renderFrame.beat * 0.003})`
+		try {
+			activeRenderer.render(renderFrame)
+		} catch (error) {
+			if (backend.value === "webgpu") {
+				console.warn(
+					"[background renderer] WebGPU render failed; using CPU",
+					error,
+				)
+				webGpuRenderer?.dispose()
+				webGpuRenderer = null
+				useCpuFallback()
+				cpuCanvas.value?.style.setProperty(
+					"transform",
+					`scale(${1.08 + renderFrame.beat * 0.003})`,
+				)
+				try {
+					cpuRenderer?.render(renderFrame)
+				} catch (fallbackError) {
+					console.warn("[background renderer] CPU fallback failed", fallbackError)
+				}
+			} else {
+				console.warn("[background renderer] CPU render failed", error)
+			}
+		}
+	}
+	frame = requestAnimationFrame(draw)
+}
+
 function startAnimation() {
 	cancelAnimationFrame(frame)
 	startedAt = 0
@@ -60,147 +158,42 @@ function startAnimation() {
 	frame = requestAnimationFrame(draw)
 }
 
-function gradientHash(x: number, y: number): [number, number] {
-	const hash = (a: number, b: number, xScale: number, yScale: number) => {
-		const value = Math.sin(a * xScale + b * yScale) * 43758.5453
-		return (value - Math.floor(value)) * 2 - 1
-	}
-	return [hash(x, y, 127.1, 311.7), hash(x, y, 269.5, 183.3)]
-}
-
-function gradientNoise(x: number, y: number) {
-	const cellX = Math.floor(x)
-	const cellY = Math.floor(y)
-	const offsetX = x - cellX
-	const offsetY = y - cellY
-	const easeX = offsetX * offsetX * (3 - 2 * offsetX)
-	const easeY = offsetY * offsetY * (3 - 2 * offsetY)
-	const dot = (cx: number, cy: number, ox: number, oy: number) => {
-		const [gx, gy] = gradientHash(cx, cy)
-		return gx * ox + gy * oy
-	}
-	const lower =
-		dot(cellX, cellY, offsetX, offsetY) * (1 - easeX) +
-		dot(cellX + 1, cellY, offsetX - 1, offsetY) * easeX
-	const upper =
-		dot(cellX, cellY + 1, offsetX, offsetY - 1) * (1 - easeX) +
-		dot(cellX + 1, cellY + 1, offsetX - 1, offsetY - 1) * easeX
-	return 0.5 + 0.5 * (lower * (1 - easeY) + upper * easeY)
-}
-
-function smoothstep(edge0: number, edge1: number, value: number) {
-	const amount = Math.max(0, Math.min(1, (value - edge0) / (edge1 - edge0)))
-	return amount * amount * (3 - 2 * amount)
-}
-
-function ditherNoise(x: number, y: number, channel: number) {
-	const value = Math.sin(
-		(x + channel * 17) * 127.1 + (y + channel * 59) * 311.7,
-	) * 43758.5453
-	return value - Math.floor(value) - 0.5
-}
-
-function flowPoint(x: number, y: number, time: number): [number, number] {
-	const degree = gradientNoise(
-		time * 0.1 + random[0] * 0.07,
-		x * y + random[1] * 0.07,
-	)
-	const angle = (((degree - 0.5) * 720 + 180) * Math.PI) / 180 + angleJitter
-	const sine = Math.sin(angle)
-	const cosine = Math.cos(angle)
-	let flowX = x * cosine - y * sine
-	let flowY = x * sine + y * cosine
-	const speed = time * flowParams[2]
-	flowX += Math.sin(flowY * flowParams[0] + speed) / flowParams[1]
-	flowY +=
-		Math.sin(flowX * flowParams[0] * 1.5 + speed) / (flowParams[1] * 0.5)
-	const tiltSine = Math.sin(flowParams[3])
-	const tiltCosine = Math.cos(flowParams[3])
-	return [
-		flowX * tiltCosine - flowY * tiltSine,
-		flowX * tiltSine + flowY * tiltCosine,
-	]
-}
-
-function draw(now: number) {
-	const element = canvas.value
-	const context = element?.getContext("2d")
-	if (!element || !context) return
-	if (!startedAt) startedAt = now
-	if (now - lastFrameAt < 1000 / 24) {
-		frame = requestAnimationFrame(draw)
-		return
-	}
-	lastFrameAt = now
-	const time = (now - startedAt) / 1000
-	const width = 224
-	const height = Math.max(
-		72,
-		Math.round(
-			(width * element.clientHeight) / Math.max(1, element.clientWidth),
-		),
-	)
-	if (element.width !== width || element.height !== height) {
-		element.width = width
-		element.height = height
-	}
-	const image = context.createImageData(width, height)
-	const colors = palette.value ?? fallback
-	const dominant = toOkLab(colors.dominant)
-	const accent = toOkLab(colors.accent)
-	const maxPaletteLightness = Math.max(dominant[0], accent[0])
-	const motionTime = time * ANIMATION_SPEED
-	for (let y = 0; y < height; y++) {
-		for (let x = 0; x < width; x++) {
-			const px = x / (width - 1)
-			const py = y / (height - 1)
-			const point = flowPoint(px - 0.5, py - 0.5, motionTime)
-			const blend = smoothstep(-0.34, 0.16, point[0])
-			const transition = 1 - Math.abs(blend * 2 - 1)
-			const lab = dominant.map(
-				(value, channel) =>
-					value * (1 - blend) + accent[channel] * blend,
-			) as [number, number, number]
-			const beat = shapeBeatPulse(beatEnergy.value)
-			lab[0] = Math.min(maxPaletteLightness, lab[0] + beat * 0.01)
-			lab[1] *= 1 + beat * 0.02
-			lab[2] *= 1 + beat * 0.02
-			const color = fromOkLab(lab)
-			const offset = (y * width + x) * 4
-			image.data[offset] = color[0] + ditherNoise(x, y, 0) * transition * 3
-			image.data[offset + 1] = color[1] + ditherNoise(x, y, 1) * transition * 3
-			image.data[offset + 2] = color[2] + ditherNoise(x, y, 2) * transition * 3
-			image.data[offset + 3] = 255
-		}
-	}
-	element.style.transform = `scale(${1.08 + shapeBeatPulse(beatEnergy.value) * 0.003})`
-	context.putImageData(image, 0, 0)
-	if (props.active) frame = requestAnimationFrame(draw)
-}
-
 watch(() => props.src, loadArtwork)
 watch(
 	() => props.active,
 	(active) => {
 		if (active) startAnimation()
-		else {
-			cancelAnimationFrame(frame)
-		}
+		else cancelAnimationFrame(frame)
 	},
 )
 
 onMounted(() => {
 	loadArtwork()
+	void initializeRenderers()
 	if (props.active) startAnimation()
 })
 
 onBeforeUnmount(() => {
+	disposed = true
 	cancelAnimationFrame(frame)
+	webGpuRenderer?.dispose()
+	cpuRenderer?.dispose()
 })
 </script>
 
 <template>
-	<canvas ref="canvas" class="background-wash" aria-hidden="true" />
+	<canvas
+		ref="webGpuCanvas"
+		class="background-wash"
+		:class="{ 'background-wash--active': backend === 'webgpu' }"
+		aria-hidden="true"
+	/>
+	<canvas
+		ref="cpuCanvas"
+		class="background-wash"
+		:class="{ 'background-wash--active': backend === 'cpu' }"
+		aria-hidden="true"
+	/>
 </template>
 
 <style scoped>
@@ -211,5 +204,10 @@ onBeforeUnmount(() => {
 	height: 50%;
 	filter: blur(6px) saturate(1.08);
 	transform: scale(1.08);
+	visibility: hidden;
+}
+
+.background-wash--active {
+	visibility: visible;
 }
 </style>

app/components/Player/Fullscreen/Background/renderers/cpu.ts

@@ -0,0 +1,116 @@
+import { fromOkLab, toOkLab } from "../palette"
+import type { BackgroundFrame, BackgroundRenderer } from "./types"
+
+function gradientHash(x: number, y: number): [number, number] {
+	const hash = (a: number, b: number, xScale: number, yScale: number) => {
+		const value = Math.sin(a * xScale + b * yScale) * 43758.5453
+		return (value - Math.floor(value)) * 2 - 1
+	}
+	return [hash(x, y, 127.1, 311.7), hash(x, y, 269.5, 183.3)]
+}
+
+function gradientNoise(x: number, y: number) {
+	const cellX = Math.floor(x)
+	const cellY = Math.floor(y)
+	const offsetX = x - cellX
+	const offsetY = y - cellY
+	const easeX = offsetX * offsetX * (3 - 2 * offsetX)
+	const easeY = offsetY * offsetY * (3 - 2 * offsetY)
+	const dot = (cx: number, cy: number, ox: number, oy: number) => {
+		const [gx, gy] = gradientHash(cx, cy)
+		return gx * ox + gy * oy
+	}
+	const lower =
+		dot(cellX, cellY, offsetX, offsetY) * (1 - easeX) +
+		dot(cellX + 1, cellY, offsetX - 1, offsetY) * easeX
+	const upper =
+		dot(cellX, cellY + 1, offsetX, offsetY - 1) * (1 - easeX) +
+		dot(cellX + 1, cellY + 1, offsetX - 1, offsetY - 1) * easeX
+	return 0.5 + 0.5 * (lower * (1 - easeY) + upper * easeY)
+}
+
+function smoothstep(edge0: number, edge1: number, value: number) {
+	const amount = Math.max(0, Math.min(1, (value - edge0) / (edge1 - edge0)))
+	return amount * amount * (3 - 2 * amount)
+}
+
+function ditherNoise(x: number, y: number, channel: number) {
+	const value = Math.sin(
+		(x + channel * 17) * 127.1 + (y + channel * 59) * 311.7,
+	) * 43758.5453
+	return value - Math.floor(value) - 0.5
+}
+
+function flowPoint(
+	x: number,
+	y: number,
+	frame: BackgroundFrame,
+): [number, number] {
+	const { random, angleJitter, flowParams, time } = frame
+	const degree = gradientNoise(
+		time * 0.1 + random[0] * 0.07,
+		x * y + random[1] * 0.07,
+	)
+	const angle = (((degree - 0.5) * 720 + 180) * Math.PI) / 180 + angleJitter
+	const sine = Math.sin(angle)
+	const cosine = Math.cos(angle)
+	let flowX = x * cosine - y * sine
+	let flowY = x * sine + y * cosine
+	const speed = time * flowParams[2]
+	flowX += Math.sin(flowY * flowParams[0] + speed) / flowParams[1]
+	flowY +=
+		Math.sin(flowX * flowParams[0] * 1.5 + speed) / (flowParams[1] * 0.5)
+	const tiltSine = Math.sin(flowParams[3])
+	const tiltCosine = Math.cos(flowParams[3])
+	return [
+		flowX * tiltCosine - flowY * tiltSine,
+		flowX * tiltSine + flowY * tiltCosine,
+	]
+}
+
+export function createCpuRenderer(
+	canvas: HTMLCanvasElement,
+): BackgroundRenderer | null {
+	const context = canvas.getContext("2d")
+	if (!context) return null
+
+	return {
+		render(frame) {
+			if (canvas.width !== frame.width || canvas.height !== frame.height) {
+				canvas.width = frame.width
+				canvas.height = frame.height
+			}
+			const image = context.createImageData(frame.width, frame.height)
+			const dominant = toOkLab(frame.palette.dominant)
+			const accent = toOkLab(frame.palette.accent)
+			const maxPaletteLightness = Math.max(dominant[0], accent[0])
+			for (let y = 0; y < frame.height; y++) {
+				for (let x = 0; x < frame.width; x++) {
+					const px = x / (frame.width - 1)
+					const py = y / (frame.height - 1)
+					const point = flowPoint(px - 0.5, py - 0.5, frame)
+					const blend = smoothstep(-0.34, 0.16, point[0])
+					const transition = 1 - Math.abs(blend * 2 - 1)
+					const lab: [number, number, number] = [
+						dominant[0] * (1 - blend) + accent[0] * blend,
+						dominant[1] * (1 - blend) + accent[1] * blend,
+						dominant[2] * (1 - blend) + accent[2] * blend,
+					]
+					lab[0] = Math.min(maxPaletteLightness, lab[0] + frame.beat * 0.01)
+					lab[1] *= 1 + frame.beat * 0.02
+					lab[2] *= 1 + frame.beat * 0.02
+					const color = fromOkLab(lab)
+					const offset = (y * frame.width + x) * 4
+					image.data[offset] = color[0] + ditherNoise(x, y, 0) * transition * 3
+					image.data[offset + 1] =
+						color[1] + ditherNoise(x, y, 1) * transition * 3
+					image.data[offset + 2] =
+						color[2] + ditherNoise(x, y, 2) * transition * 3
+					image.data[offset + 3] = 255
+				}
+			}
+			context.putImageData(image, 0, 0)
+		},
+		dispose() {},
+	}
+}

app/components/Player/Fullscreen/Background/renderers/shader.wgsl

@@ -0,0 +1,133 @@
+struct Params {
+	resolutionTimeBeat: vec4f,
+	randomAndJitter: vec4f,
+	flowParams: vec4f,
+	dominant: vec4f,
+	accent: vec4f,
+}
+
+@group(0) @binding(0) var<uniform> params: Params;
+
+fn hash(a: f32, b: f32, xScale: f32, yScale: f32) -> f32 {
+	let value = sin(a * xScale + b * yScale) * 43758.5453;
+	return fract(value) * 2.0 - 1.0;
+}
+
+fn gradientHash(cell: vec2f) -> vec2f {
+	return vec2f(
+		hash(cell.x, cell.y, 127.1, 311.7),
+		hash(cell.x, cell.y, 269.5, 183.3),
+	);
+}
+
+fn gradientDot(cell: vec2f, offset: vec2f) -> f32 {
+	return dot(gradientHash(cell), offset);
+}
+
+fn gradientNoise(point: vec2f) -> f32 {
+	let cell = floor(point);
+	let offset = fract(point);
+	let ease = offset * offset * (3.0 - 2.0 * offset);
+	let lower = mix(
+		gradientDot(cell, offset),
+		gradientDot(cell + vec2f(1.0, 0.0), offset - vec2f(1.0, 0.0)),
+		ease.x,
+	);
+	let upper = mix(
+		gradientDot(cell + vec2f(0.0, 1.0), offset - vec2f(0.0, 1.0)),
+		gradientDot(cell + vec2f(1.0, 1.0), offset - vec2f(1.0, 1.0)),
+		ease.x,
+	);
+	return 0.5 + 0.5 * mix(lower, upper, ease.y);
+}
+
+fn flowPoint(point: vec2f, time: f32) -> vec2f {
+	let degree = gradientNoise(vec2f(
+		time * 0.1 + params.randomAndJitter.x * 0.07,
+		point.x * point.y + params.randomAndJitter.y * 0.07,
+	));
+	let angle = ((degree - 0.5) * 720.0 + 180.0) * 0.017453292519943295
+		+ params.randomAndJitter.z;
+	let sine = sin(angle);
+	let cosine = cos(angle);
+	var flow = vec2f(
+		point.x * cosine - point.y * sine,
+		point.x * sine + point.y * cosine,
+	);
+	let speed = time * params.flowParams.z;
+	flow.x += sin(flow.y * params.flowParams.x + speed) / params.flowParams.y;
+	flow.y += sin(flow.x * params.flowParams.x * 1.5 + speed)
+		/ (params.flowParams.y * 0.5);
+	let tiltSine = sin(params.flowParams.w);
+	let tiltCosine = cos(params.flowParams.w);
+	return vec2f(
+		flow.x * tiltCosine - flow.y * tiltSine,
+		flow.x * tiltSine + flow.y * tiltCosine,
+	);
+}
+
+fn linearToSrgb(value: f32) -> f32 {
+	if (value <= 0.0031308) {
+		return 12.92 * value;
+	}
+	return 1.055 * pow(max(value, 0.0), 1.0 / 2.4) - 0.055;
+}
+
+fn fromOkLab(lab: vec3f) -> vec3f {
+	let lRoot = lab.x + 0.3963377774 * lab.y + 0.2158037573 * lab.z;
+	let mRoot = lab.x - 0.1055613458 * lab.y - 0.0638541728 * lab.z;
+	let sRoot = lab.x - 0.0894841775 * lab.y - 1.291485548 * lab.z;
+	let l = lRoot * lRoot * lRoot;
+	let m = mRoot * mRoot * mRoot;
+	let s = sRoot * sRoot * sRoot;
+	let red = 4.0767416621 * l - 3.3077115913 * m + 0.2309699292 * s;
+	let green = -1.2684380046 * l + 2.6097574011 * m - 0.3413193965 * s;
+	let blue = -0.0041960863 * l - 0.7034186147 * m + 1.707614701 * s;
+	return clamp(vec3f(
+		linearToSrgb(red),
+		linearToSrgb(green),
+		linearToSrgb(blue),
+	), vec3f(0.0), vec3f(1.0));
+}
+
+fn ditherNoise(x: f32, y: f32, channel: f32) -> f32 {
+	let value = sin(
+		(x + channel * 17.0) * 127.1 + (y + channel * 59.0) * 311.7,
+	) * 43758.5453;
+	return fract(value) - 0.5;
+}
+
+@vertex
+fn vertexMain(@builtin(vertex_index) index: u32) -> @builtin(position) vec4f {
+	var positions = array<vec2f, 3>(
+		vec2f(-1.0, -1.0),
+		vec2f(3.0, -1.0),
+		vec2f(-1.0, 3.0),
+	);
+	return vec4f(positions[index], 0.0, 1.0);
+}
+
+@fragment
+fn fragmentMain(@builtin(position) position: vec4f) -> @location(0) vec4f {
+	let dimensions = params.resolutionTimeBeat.xy;
+	let time = params.resolutionTimeBeat.z;
+	let beat = params.resolutionTimeBeat.w;
+	let uv = position.xy / dimensions;
+	let point = flowPoint(uv - vec2f(0.5), time);
+	let blend = smoothstep(-0.34, 0.16, point.x);
+	let transition = 1.0 - abs(blend * 2.0 - 1.0);
+	var lab = mix(params.dominant.xyz, params.accent.xyz, blend);
+	lab.x = min(params.dominant.w, lab.x + beat * 0.01);
+	lab.y = lab.y * (1.0 + beat * 0.02);
+	lab.z = lab.z * (1.0 + beat * 0.02);
+	let color = fromOkLab(lab);
+	let pixel = floor(position.xy);
+	let noise = vec3f(
+		ditherNoise(pixel.x, pixel.y, 0.0),
+		ditherNoise(pixel.x, pixel.y, 1.0),
+		ditherNoise(pixel.x, pixel.y, 2.0),
+	);
+	let dithered = clamp(color + noise * transition * (3.0 / 255.0),
+		vec3f(0.0), vec3f(1.0));
+	return vec4f(dithered, 1.0);
+}

app/components/Player/Fullscreen/Background/renderers/types.ts

@@ -0,0 +1,17 @@
+import type { AlbumPalette } from "../palette"
+
+export interface BackgroundFrame {
+	width: number
+	height: number
+	time: number
+	beat: number
+	random: [number, number]
+	angleJitter: number
+	flowParams: [number, number, number, number]
+	palette: AlbumPalette
+}
+
+export interface BackgroundRenderer {
+	render(frame: BackgroundFrame): void
+	dispose(): void
+}

app/components/Player/Fullscreen/Background/renderers/webgpu.ts

@@ -0,0 +1,181 @@
+import { toOkLab } from "../palette"
+import shader from "./shader.wgsl?raw"
+import type { BackgroundFrame, BackgroundRenderer } from "./types"
+
+const uniformUsage = 0x0040 | 0x0008
+
+interface GpuBuffer {
+	destroy(): void
+}
+
+interface GpuPass {
+	setPipeline(pipeline: unknown): void
+	setBindGroup(index: number, bindGroup: unknown): void
+	draw(vertexCount: number, instanceCount?: number): void
+	end(): void
+}
+
+interface GpuDevice {
+	queue: {
+		writeBuffer(buffer: GpuBuffer, offset: number, data: Float32Array): void
+		submit(commands: unknown[]): void
+	}
+	lost: Promise<{ message: string }>
+	createBuffer(descriptor: { size: number; usage: number }): GpuBuffer
+	createShaderModule(descriptor: { code: string }): {
+		getCompilationInfo(): Promise<{
+			messages: Array<{ type: string; message: string }>
+		}>
+	}
+	createRenderPipeline(descriptor: unknown): {
+		getBindGroupLayout(index: number): unknown
+	}
+	createBindGroup(descriptor: unknown): unknown
+	createCommandEncoder(): {
+		beginRenderPass(descriptor: unknown): GpuPass
+		finish(): unknown
+	}
+	destroy(): void
+}
+
+interface GpuAdapter {
+	requestDevice(): Promise<GpuDevice>
+}
+
+interface GpuApi {
+	requestAdapter(): Promise<GpuAdapter | null>
+	getPreferredCanvasFormat(): string
+}
+
+interface GpuCanvasContext {
+	configure(options: {
+		device: GpuDevice
+		format: string
+		alphaMode: "opaque"
+	}): void
+	getCurrentTexture(): { createView(): unknown }
+	unconfigure(): void
+}
+
+export async function createWebGpuRenderer(
+	canvas: HTMLCanvasElement,
+	onDeviceLost: () => void,
+): Promise<BackgroundRenderer | null> {
+	let device: GpuDevice | null = null
+	let context: GpuCanvasContext | null = null
+	let uniformBuffer: GpuBuffer | null = null
+	try {
+		const gpu = (navigator as unknown as { gpu?: GpuApi }).gpu
+		if (!gpu) {
+			console.info("[background renderer] WebGPU API unavailable; using CPU")
+			return null
+		}
+		const adapter = await gpu.requestAdapter()
+		if (!adapter) {
+			console.info("[background renderer] no WebGPU adapter; using CPU")
+			return null
+		}
+		device = await adapter.requestDevice()
+		const rawContext = (canvas.getContext as (kind: string) => unknown).call(
+			canvas,
+			"webgpu",
+		)
+		if (!rawContext) {
+			device.destroy()
+			return null
+		}
+		context = rawContext as GpuCanvasContext
+		const format = gpu.getPreferredCanvasFormat()
+		context.configure({ device, format, alphaMode: "opaque" })
+
+		const shaderModule = device.createShaderModule({ code: shader })
+		const compilation = await shaderModule.getCompilationInfo()
+		const shaderErrors = compilation.messages.filter(
+			(message) => message.type === "error",
+		)
+		if (shaderErrors.length) {
+			throw new Error(shaderErrors.map((message) => message.message).join("\n"))
+		}
+		const pipeline = device.createRenderPipeline({
+			layout: "auto",
+			vertex: { module: shaderModule, entryPoint: "vertexMain" },
+			fragment: {
+				module: shaderModule,
+				entryPoint: "fragmentMain",
+				targets: [{ format }],
+			},
+			primitive: { topology: "triangle-list" },
+		})
+		uniformBuffer = device.createBuffer({ size: 80, usage: uniformUsage })
+		const bindGroup = device.createBindGroup({
+			layout: pipeline.getBindGroupLayout(0),
+			entries: [{ binding: 0, resource: { buffer: uniformBuffer } }],
+		})
+		const activeDevice = device
+		const activeContext = context
+		const activeBuffer = uniformBuffer
+		let disposed = false
+		void device.lost.then(() => {
+			if (!disposed) onDeviceLost()
+		})
+
+		return {
+			render(frame: BackgroundFrame) {
+				if (canvas.width !== frame.width || canvas.height !== frame.height) {
+					canvas.width = frame.width
+					canvas.height = frame.height
+				}
+				const dominant = toOkLab(frame.palette.dominant)
+				const accent = toOkLab(frame.palette.accent)
+				const uniforms = new Float32Array([
+					frame.width,
+					frame.height,
+					frame.time,
+					frame.beat,
+					frame.random[0],
+					frame.random[1],
+					frame.angleJitter,
+					0,
+					...frame.flowParams,
+					dominant[0],
+					dominant[1],
+					dominant[2],
+					Math.max(dominant[0], accent[0]),
+					accent[0],
+					accent[1],
+					accent[2],
+					0,
+				])
+				activeDevice.queue.writeBuffer(activeBuffer, 0, uniforms)
+				const encoder = activeDevice.createCommandEncoder()
+				const pass = encoder.beginRenderPass({
+					colorAttachments: [
+						{
+							view: activeContext.getCurrentTexture().createView(),
+							clearValue: { r: 0, g: 0, b: 0, a: 1 },
+							loadOp: "clear",
+							storeOp: "store",
+						},
+					],
+				})
+				pass.setPipeline(pipeline)
+				pass.setBindGroup(0, bindGroup)
+				pass.draw(3, 1)
+				pass.end()
+				activeDevice.queue.submit([encoder.finish()])
+			},
+			dispose() {
+				disposed = true
+				activeContext.unconfigure()
+				activeBuffer.destroy()
+				activeDevice.destroy()
+			},
+		}
+	} catch (error) {
+		console.warn("[background renderer] WebGPU unavailable; using CPU", error)
+		uniformBuffer?.destroy()
+		context?.unconfigure()
+		device?.destroy()
+		return null
+	}
+}