Created
December 22, 2017 05:55
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Quick snowing
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| <!DOCTYPE html><html> | |
| <head><meta charset="UTF-8"><style>html,body{background:#bababa}</style></head> | |
| <body><script src="snow.js"></script></body> | |
| </html> |
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| var canvas = document.createElement('canvas'); | |
| document.body.appendChild(canvas); | |
| canvas.style.height = '100%'; | |
| canvas.style.width = '100%'; | |
| canvas.style.position = 'fixed'; | |
| canvas.style.top = '0'; | |
| canvas.style.left = '0'; | |
| var w, h; | |
| function resized() { | |
| w = canvas.offsetWidth * devicePixelRatio; | |
| h = canvas.offsetHeight * devicePixelRatio; | |
| canvas.width = w; | |
| canvas.height = h; | |
| } | |
| window.addEventListener('resize', resized); | |
| resized(); | |
| var ctx = canvas.getContext('2d'); | |
| var nextSnowDrop = 0; | |
| var snowDrops = []; | |
| function draw() { | |
| ctx.clearRect(0, 0, w, h); | |
| ctx.fillStyle = '#FFFFFF'; | |
| if (nextSnowDrop <= 0) { | |
| snowDrops.push({ x: Math.random() * .8 + .1, y: 0, speed: Math.random() * 10 - 5, accel: 0, speedY: Math.random() * 2 + 1 }); | |
| nextSnowDrop = 10; | |
| } else { | |
| nextSnowDrop--; | |
| } | |
| ctx.beginPath(); | |
| snowDrops.forEach(function (i) { | |
| var spd = i.speed, x = i.x * w, y = i.y, accel = i.accel; | |
| i.y += i.speedY; | |
| x += spd; | |
| i.x = x / w; | |
| accel += Math.random() * .04 - .02; | |
| if (accel < -1) accel = -1; | |
| else if (accel > 1) accel = 1; | |
| if (spd < -2) spd = -2; | |
| else if (spd > 2) spd = 2; | |
| spd += accel; | |
| i.accel = accel; | |
| i.speed = spd; | |
| ctx.moveTo(x, y); | |
| ctx.arc(x, y, 3 * devicePixelRatio, 0, Math.PI * 2); | |
| ctx.fill(); | |
| if (y > h) { | |
| snowDrops.splice(snowDrops.indexOf(i), 1); | |
| } | |
| }); | |
| ctx.closePath(); | |
| requestAnimationFrame(draw); | |
| } | |
| requestAnimationFrame(draw); |
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