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'use client' | ||
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import React, { useEffect } from 'react' | ||
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interface Props { | ||
speedFactor?: number | ||
backgroundColor?: string | ||
starColor?: [number, number, number] | ||
starCount?: number | ||
} | ||
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export default function StarBackground(props: Props) { | ||
const { | ||
speedFactor = 0.05, | ||
backgroundColor = 'black', | ||
starColor = [255, 255, 255], | ||
starCount = 5000, | ||
} = props | ||
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useEffect(() => { | ||
const canvas = document.getElementById( | ||
'starfield' | ||
) as HTMLCanvasElement | null | ||
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if (canvas) { | ||
const c = canvas.getContext('2d') | ||
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if (c) { | ||
let w = window.innerWidth | ||
let h = window.innerHeight | ||
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const setCanvasExtents = () => { | ||
canvas.width = w | ||
canvas.height = h | ||
} | ||
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setCanvasExtents() | ||
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window.onresize = () => { | ||
setCanvasExtents() | ||
} | ||
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const makeStars = (count: number) => { | ||
const out = [] | ||
for (let i = 0; i < count; i++) { | ||
const s = { | ||
x: Math.random() * 1600 - 800, | ||
y: Math.random() * 900 - 450, | ||
z: Math.random() * 1000, | ||
} | ||
out.push(s) | ||
} | ||
return out | ||
} | ||
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const stars = makeStars(starCount) | ||
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const clear = () => { | ||
c.fillStyle = backgroundColor | ||
c.fillRect(0, 0, canvas.width, canvas.height) | ||
} | ||
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const putPixel = (x: number, y: number, brightness: number) => { | ||
const rgb = | ||
'rgba(' + | ||
starColor[0] + | ||
',' + | ||
starColor[1] + | ||
',' + | ||
starColor[2] + | ||
',' + | ||
brightness + | ||
')' | ||
c.fillStyle = rgb | ||
c.fillRect(x, y, 1, 1) | ||
} | ||
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const moveStars = (distance: number) => { | ||
const count = stars.length | ||
for (let i = 0; i < count; i++) { | ||
const s = stars[i] | ||
s.z -= distance | ||
while (s.z <= 1) { | ||
s.z += 1000 | ||
} | ||
} | ||
} | ||
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let prevTime: number | ||
const init = (time: number) => { | ||
prevTime = time | ||
requestAnimationFrame(tick) | ||
} | ||
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const tick = (time: number) => { | ||
const elapsed = time - prevTime | ||
prevTime = time | ||
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moveStars(elapsed * speedFactor) | ||
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clear() | ||
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const cx = w / 2 | ||
const cy = h / 2 | ||
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const count = stars.length | ||
for (let i = 0; i < count; i++) { | ||
const star = stars[i] | ||
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const x = cx + star.x / (star.z * 0.001) | ||
const y = cy + star.y / (star.z * 0.001) | ||
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if (x < 0 || x >= w || y < 0 || y >= h) { | ||
continue | ||
} | ||
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const d = star.z / 1000.0 | ||
const b = 1 - d * d | ||
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putPixel(x, y, b) | ||
} | ||
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requestAnimationFrame(tick) | ||
} | ||
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requestAnimationFrame(init) | ||
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// add window resize listener: | ||
window.addEventListener('resize', function () { | ||
w = window.innerWidth | ||
h = window.innerHeight | ||
setCanvasExtents() | ||
}) | ||
} else { | ||
console.error('Could not get 2d context from canvas element') | ||
} | ||
} else { | ||
console.error('Could not find canvas element with id "starfield"') | ||
} | ||
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return () => { | ||
window.onresize = null | ||
} | ||
}, [starColor, backgroundColor, speedFactor, starCount]) | ||
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return ( | ||
<canvas | ||
id="starfield" | ||
style={{ | ||
padding: 0, | ||
margin: 0, | ||
position: 'fixed', | ||
top: 0, | ||
right: 0, | ||
bottom: 0, | ||
left: 0, | ||
zIndex: 10, | ||
opacity: 1, | ||
pointerEvents: 'none', | ||
mixBlendMode: 'screen', | ||
}} | ||
></canvas> | ||
) | ||
} |
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