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'use strict'; |
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function randomBetween(min: number, max: number) { |
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return min + Math.random() * (max - min); |
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} |
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class Snowflake { |
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alpha = 0; |
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radius = 0; |
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x = 0; |
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y = 0; |
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private _vx = 0; |
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private _vy = 0; |
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constructor() { |
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this.reset(); |
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} |
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reset() { |
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this.alpha = randomBetween(0.1, 0.9); |
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this.radius = randomBetween(1, 4); |
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this.x = randomBetween(0, window.innerWidth); |
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this.y = randomBetween(0, -window.innerHeight); |
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this._vx = randomBetween(-3, 3); |
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this._vy = randomBetween(2, 5); |
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} |
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update() { |
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this.x += this._vx; |
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this.y += this._vy; |
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if (this.y + this.radius > window.innerHeight) { |
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this.reset(); |
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} |
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} |
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} |
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export class Snow { |
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snowing = false; |
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private readonly _canvas: any; |
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private readonly _ctx: any; |
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private _height: number = 0; |
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private _width: number = 0; |
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private readonly _snowflakes: Snowflake[] = []; |
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private readonly _clearBound: any; |
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private readonly _updateBound: any; |
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constructor() { |
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this._clearBound = this.clear.bind(this); |
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this._updateBound = this.update.bind(this); |
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this._canvas = document.querySelector('canvas.snow'); |
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this._ctx = this._canvas.getContext('2d'); |
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const trigger = document.querySelector('.snow__trigger'); |
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if (trigger) { |
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trigger.addEventListener('click', () => this.onToggle()); |
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} |
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window.addEventListener('resize', () => this.onResize()); |
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this.onResize(); |
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this.onToggle(); |
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} |
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onToggle() { |
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this.snowing = !this.snowing; |
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if (this.snowing) { |
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this.createSnowflakes(); |
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requestAnimationFrame(this._updateBound); |
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} |
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} |
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onResize() { |
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this._height = window.innerHeight; |
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this._width = window.innerWidth; |
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this._canvas.width = this._width; |
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this._canvas.height = this._height; |
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} |
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clear() { |
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this._ctx.clearRect(0, 0, this._canvas.width, this._canvas.height); |
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this._snowflakes.length = 0; |
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} |
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createSnowflakes() { |
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const flakes = window.innerWidth / 4; |
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for (let i = 0; i < flakes; i++) { |
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this._snowflakes.push(new Snowflake()); |
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} |
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} |
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update() { |
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this._ctx.clearRect(0, 0, this._width, this._height); |
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const color = document.body.classList.contains('vscode-light') ? '#424242' : '#fff'; |
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for (const flake of this._snowflakes) { |
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flake.update(); |
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this._ctx.save(); |
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this._ctx.fillStyle = color; |
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this._ctx.beginPath(); |
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this._ctx.arc(flake.x, flake.y, flake.radius, 0, Math.PI * 2); |
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this._ctx.closePath(); |
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this._ctx.globalAlpha = flake.alpha; |
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this._ctx.fill(); |
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this._ctx.restore(); |
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} |
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requestAnimationFrame(this.snowing ? this._updateBound : this._clearBound); |
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} |
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} |