export function bgStart(){ // modified version of random-normal function normalPool(o){var r=0;do{var a=Math.round(normal({mean:o.mean,dev:o.dev}));if(a=0)return o.pool[a];r++}while(r<100)}function randomNormal(o){if(o=Object.assign({mean:0,dev:1,pool:[]},o),Array.isArray(o.pool)&&o.pool.length>0)return normalPool(o);var r,a,n,e,l=o.mean,t=o.dev;do{r=(a=2*Math.random()-1)*a+(n=2*Math.random()-1)*n}while(r>=1);return e=a*Math.sqrt(-2*Math.log(r)/r),t*e+l} const NUM_PARTICLES = 100; const PARTICLE_SIZE = 0.5; // View heights const SPEED = 10000; // Milliseconds let particles = []; function rand(low, high) { return Math.random() * (high - low) + low; } function createParticle(canvas) { const colour = { r: 255, g: randomNormal({ mean: 125, dev: 20 }), b: 50, a: rand(0, 1), }; return { x: -2, y: -2, diameter: Math.max(0, randomNormal({ mean: PARTICLE_SIZE, dev: PARTICLE_SIZE / 2 })), duration: randomNormal({ mean: SPEED, dev: SPEED * 0.1 }), amplitude: randomNormal({ mean: 16, dev: 2 }), offsetY: randomNormal({ mean: 0, dev: 10 }), arc: Math.PI * 2, startTime: performance.now() - rand(0, SPEED), colour: `rgba(${colour.r}, ${colour.g}, ${colour.b}, ${colour.a})`, } } function moveParticle(particle, canvas, time) { const progress = ((time - particle.startTime) % particle.duration) / particle.duration; return { ...particle, x: progress, y: ((Math.sin(progress * particle.arc) * particle.amplitude) + particle.offsetY), }; } function drawParticle(particle, canvas, ctx) { canvas = document.getElementById('canvas'); const vh = canvas.height / 100; ctx.fillStyle = particle.colour; ctx.beginPath(); ctx.ellipse( particle.x * canvas.width, particle.y * vh + (canvas.height / 2), particle.diameter * vh, particle.diameter * vh, 0, 0, 2 * Math.PI ); ctx.fill(); } function draw(time, canvas, ctx) { // Move particles particles.forEach((particle, index) => { particles[index] = moveParticle(particle, canvas, time); }) // Clear the canvas ctx.clearRect(0, 0, canvas.width, canvas.height); // Draw the particles particles.forEach((particle) => { drawParticle(particle, canvas, ctx); }) // Schedule next frame requestAnimationFrame((time) => draw(time, canvas, ctx)); } function initializeCanvas() { let canvas = document.getElementById('canvas'); canvas.width = canvas.offsetWidth * window.devicePixelRatio; canvas.height = canvas.offsetHeight * window.devicePixelRatio; canvas.style.background = 'linear-gradient(to bottom, rgb(10, 10, 50) 0%,rgb(60, 10, 60) 100%)' canvas.style.verticalAlign = 'middle' canvas.overflow = 'hidden' let ctx = canvas.getContext("2d"); window.addEventListener('onresize', () => { canvas.width = canvas.offsetWidth * window.devicePixelRatio; canvas.height = canvas.offsetHeight * window.devicePixelRatio; canvas.style.background = 'linear-gradient(to bottom, rgb(10, 10, 50) 0%,rgb(60, 10, 60) 100%)' canvas.style.verticalAlign = 'middle' canvas.overflow = 'hidden' ctx = canvas.getContext("2d"); }) return [canvas, ctx]; } function startAnimation() { const [canvas, ctx] = initializeCanvas(); // Create a bunch of particles for (let i = 0; i < NUM_PARTICLES; i++) { particles.push(createParticle(canvas)); } requestAnimationFrame((time) => draw(time, canvas, ctx)); }; // Start animation when document is loaded (function () { if (document.readystate !== 'loading') { startAnimation(); } else { document.addEventListener('DOMContentLoaded', () => { startAnimation(); }) } }()); }