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<script lang="ts">
import { onDestroy, onMount } from 'svelte'
import { createRNG } from '@hollowdark/rng/seeded'
import { reduceMotion } from '@hollowdark/lib/display/state'
import { LEAF_VARIANTS } from '@hollowdark/lib/leaves/variants'
import { spawnLeaf } from '@hollowdark/lib/leaves/spawn'
import { isLeafOffscreen, stepLeaf } from '@hollowdark/lib/leaves/physics'
import {
initialWindSystem,
particleOpacity,
stepWind,
type IdSource
} from '@hollowdark/lib/leaves/wind'
import type { Leaf, SceneDimensions, WindSystem } from '@hollowdark/lib/leaves/types'
const TARGET_LEAF_COUNT = 14
const GROUND_Y_RATIO = 0.86
const rng = createRNG(Math.floor(performance.now() * 1000) | 0)
let container: HTMLDivElement | null = $state(null)
let scene: SceneDimensions = $state({ width: 0, height: 0, groundY: 0 })
let leaves: Leaf[] = $state([])
let wind: WindSystem = $state(initialWindSystem(rng))
let rafId: number | null = null
let lastTimeMs = 0
let nextLeafId = 0
let nextGustId = 0
let nextParticleId = 0
let resizeObserver: ResizeObserver | null = null
const ids: IdSource = {
nextGustId: () => nextGustId++,
nextParticleId: () => nextParticleId++
}
function measure(): void {
if (!container) return
const rect = container.getBoundingClientRect()
scene = {
width: rect.width,
height: rect.height,
groundY: rect.height * GROUND_Y_RATIO
}
}
onMount(() => {
measure()
for (let i = 0; i < TARGET_LEAF_COUNT; i++) {
leaves = [...leaves, spawnLeaf(nextLeafId++, scene, rng)]
}
if (container && typeof ResizeObserver !== 'undefined') {
resizeObserver = new ResizeObserver(measure)
resizeObserver.observe(container)
}
const tick = (nowMs: number): void => {
const dtMs = Math.min(50, nowMs - lastTimeMs)
lastTimeMs = nowMs
const dt = dtMs / 1000
const timeS = nowMs / 1000
wind = stepWind(wind, dtMs, scene, rng, ids)
const next: Leaf[] = []
for (const leaf of leaves) {
const advanced = stepLeaf(leaf, dt, timeS, wind, scene)
if (!isLeafOffscreen(advanced, scene)) {
next.push(advanced)
}
}
while (next.length < TARGET_LEAF_COUNT) {
next.push(spawnLeaf(nextLeafId++, scene, rng))
}
leaves = next
rafId = requestAnimationFrame(tick)
}
rafId = requestAnimationFrame((nowMs) => {
lastTimeMs = nowMs
rafId = requestAnimationFrame(tick)
})
})
onDestroy(() => {
if (rafId !== null) cancelAnimationFrame(rafId)
resizeObserver?.disconnect()
})
</script>
{#if !$reduceMotion}
<div class="leaf-scene" bind:this={container} aria-hidden="true">
<svg class="defs" width="0" height="0" focusable="false">
<defs>
{#each LEAF_VARIANTS as variant (variant.id)}
<symbol id="leaf-{variant.id}" viewBox={variant.viewBox}>
<path
d={variant.pathData}
fill="currentColor"
stroke="currentColor"
stroke-width="0.6"
stroke-linejoin="round"
/>
</symbol>
{/each}
</defs>
</svg>
<div class="ground" style:top="{scene.groundY}px"></div>
{#if wind.activeGust}
{#each wind.activeGust.particles as particle (particle.id)}
<div
class="wind-particle"
style:left="{particle.x}px"
style:top="{particle.y}px"
style:width="{particle.size}px"
style:height="{particle.size}px"
style:opacity={particleOpacity(particle)}
></div>
{/each}
{/if}
{#each leaves as leaf (leaf.id)}
<svg
class="leaf"
viewBox="0 0 40 48"
style:left="{leaf.x}px"
style:top="{leaf.y}px"
style:width="{leaf.size}px"
style:color={leaf.color}
style:transform="translate(-50%, -50%) rotate({leaf.rotation}deg)"
focusable="false"
>
<use href="#leaf-{leaf.variantId}" />
</svg>
{/each}
</div>
{/if}
<style>
.leaf-scene {
position: absolute;
inset: 0;
overflow: hidden;
pointer-events: none;
z-index: 0;
}
.defs {
position: absolute;
width: 0;
height: 0;
}
.ground {
position: absolute;
left: 0;
right: 0;
height: 1px;
background: linear-gradient(
to right,
rgba(232, 226, 213, 0) 0%,
rgba(232, 226, 213, 0.04) 30%,
rgba(232, 226, 213, 0.04) 70%,
rgba(232, 226, 213, 0) 100%
);
opacity: 0.6;
}
.leaf {
position: absolute;
display: block;
will-change: transform, top, left;
filter: drop-shadow(0 1px 1px rgba(0, 0, 0, 0.25));
}
.wind-particle {
position: absolute;
border-radius: 50%;
background: rgba(232, 226, 213, 0.45);
transform: translate(-50%, -50%);
pointer-events: none;
box-shadow: 0 0 4px rgba(232, 226, 213, 0.2);
}
@media (prefers-reduced-motion: reduce) {
.leaf-scene {
display: none;
}
}
</style>
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