fantus/components/background.tsx

import React, { useEffect } from 'react'
import { PerspectiveCamera, Scene, BufferGeometry, BufferAttribute, ShaderMaterial, Color, Points, WebGLRenderer, Camera } from 'three'

import '../styles/backgorund.styl'

// const SEPARATION = 150, AMOUNTX = 200, AMOUNTY = 200, HEIGHT = 75
const SEPARATION = 150, AMOUNTX = 50, AMOUNTY = 50, HEIGHT = 75

let container: HTMLElement | null
let camera: PerspectiveCamera
let scene: Scene
let renderer: WebGLRenderer

let count = 1
let particles: Points

let mouseX = 0
let mouseY = 0
let windowHalfX = window.innerWidth / 2
let windowHalfY = window.innerHeight / 2

function init() {
    container = window.document.getElementById('bg') || document.createElement('div')

    document.body.appendChild(container)
    camera = new PerspectiveCamera(75, window.innerWidth / window.innerHeight, 1, 10000000)
    scene = new Scene()

    const numParticles = AMOUNTX * AMOUNTY
    const positions = new Float32Array(numParticles * 3)
    const scales = new Float32Array(numParticles)

    let i = 0, j = 0
    for (let ix = 0; ix < AMOUNTX; ix++) {
        for (let iy = 0; iy < AMOUNTY; iy++) {
            positions[i] = ix * SEPARATION - ((AMOUNTX * SEPARATION) / 2) // x
            positions[i + 1] = 0 // y
            positions[i + 2] = iy * SEPARATION - ((AMOUNTY * SEPARATION) / 2) // z
            scales[j] = 1
            i += 3
            j++
        }
    }

    const geometry = new BufferGeometry()
    geometry.setAttribute('position', new BufferAttribute(positions, 3))
    geometry.setAttribute('scale', new BufferAttribute(scales, 1))

    const material = new ShaderMaterial({
        uniforms: {
            color: { value: new Color(0xffffff) },
        },
        vertexShader: document.getElementById('vertexshader')?.textContent || '',
        fragmentShader: document.getElementById('fragmentshader')?.textContent || ''
    })

    particles = new Points(geometry, material)
    scene.add(particles)

    renderer = new WebGLRenderer({ antialias: true })
    renderer.setPixelRatio(window.devicePixelRatio)
    renderer.setSize(window.innerWidth, window.innerHeight)

    container.appendChild(renderer.domElement)
    document.addEventListener('mousemove', onDocumentMouseMove, false)
    document.addEventListener('touchstart', onDocumentTouchStart, false)
    document.addEventListener('touchmove', onDocumentTouchMove, false)

    window.addEventListener('resize', onWindowResize, false)
}

function onWindowResize() {
    windowHalfX = window.innerWidth / 2
    windowHalfY = window.innerHeight / 2
    camera.aspect = window.innerWidth / window.innerHeight
    camera.updateProjectionMatrix()
    renderer.setSize(window.innerWidth, window.innerHeight)
}

function setMouse(x: number, y: number) {
    mouseX = (x - windowHalfX) / windowHalfX
    mouseY = -(y - windowHalfY) / windowHalfY
}


function onDocumentMouseMove(event: MouseEvent) {
    setMouse(event.clientX, event.clientY)
}

function onDocumentTouchStart(event: TouchEvent) {
    if (event.touches.length === 1) {
        event.preventDefault()
        setMouse(event.touches[0].pageX, event.touches[0].pageY)
    }
}

function onDocumentTouchMove(event: TouchEvent) {
    if (event.touches.length === 1) {
        event.preventDefault()
        setMouse(event.touches[0].pageX, event.touches[0].pageY)
    }
}

function animate() {
    requestAnimationFrame(animate)
    render()
}

function render() {
    // Noence from 0.0 to 1.0
    const noence = (Math.sin(count / 4) + 1) / 2
    const noence_inv = 1 - noence

    camera.position.x = -mouseX * 500
    camera.position.y = 1000 - mouseY * 500
    camera.position.z = 1000 - mouseY * 250
    camera.lookAt(scene.position)

    if (particles.geometry instanceof BufferGeometry) {
        const positions = particles.geometry.attributes.position.array
        const scales = particles.geometry.attributes.scale.array
        let i = 0, j = 0
        for (let ix = 0; ix < AMOUNTX; ix++) {
            for (let iy = 0; iy < AMOUNTY; iy++) {
                const dx = Math.sin((ix + count) * 0.3)
                const dy = Math.sin((iy + count) * 0.5)
                // @ts-ignore
                positions[i + 1] = (dx * HEIGHT) + (dy * HEIGHT)
                // @ts-ignore
                scales[j] = (dx + 1) * 8 + (dy + 1) * 8
                i += 3
                j++
            }
        }


        // @ts-ignore
        particles.material.uniforms.color.value.setRGB(1 - 0.5 * noence_inv, 0.2 + 0.8 * noence, 1)
        if (particles.geometry.attributes.position instanceof BufferAttribute)
            particles.geometry.attributes.position.needsUpdate = true
        if (particles.geometry.attributes.scale instanceof BufferAttribute)
            particles.geometry.attributes.scale.needsUpdate = true

    }
    renderer.render(scene, camera)

    count += 0.05 + (0.01 * noence)
}

const Background: React.FC = ({ children }) => {

    useEffect(() => {
        init()
        animate()
    }, [])

    return <div id='bg'>
        {children}
    </div>
}

export default Background