キャンバスは愛と虹の雨の効果を実現します-H5 チュートリアル-php.cn

キャンバスは愛と虹の雨の効果を実現します

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リリース： 2018-07-03 11:28:48

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3423 人が閲覧しました

この記事では、参考値の高い愛と虹の雨エフェクトをキャンバスに実装した例を中心に紹介します。一緒に見てみましょう

レンダリング:

コードは次のとおりです:

<!doctype html>
 <html>
 <head>
 <meta charset="utf-8">
 <title></title>
 </head>
 <body>
 <canvas id="canvas"></canvas>
 <script>
 var canvas = document.getElementById(&#39;canvas&#39;),
 ctx = canvas.getContext(&#39;2d&#39;),
 canvasW = canvas.width = window.innerWidth,
 canvasH = canvas.height = window.innerHeight,
 canvasWHalf = canvasW / 2,
 canvasHHalf = canvasH / 2,
 xoff = canvasWHalf - 306,
 yoff = 50,
 bg = &#39;00061a&#39;,
 id = 0,
 raindrops = [],
 minSize = 1,
 maxSize = 4,
 minSpeed = 5,
 maxSpeed = 20,
 minHue = 0,
 maxHue = 360,
 maxAmount = 50;
 function random(min, max) {
 if (arguments.length < 2) {
  max = min;
  min = 0;
 }
 return Math.floor(Math.random() * (max - min) + min);
 }
 function hexToRGB(hex, opacity) {
 var rgb = &#39;&#39;;
 hex.match(/.{2}/g).forEach(function(n) {
  rgb += (parseInt(n, 16)) + &#39;,&#39;;
 });
 return &#39;rgba(&#39; + rgb + opacity + &#39;)&#39;;
 }
 function draw() {
 // Heart
 ctx.fillStyle = hexToRGB(bg, &#39;0.1&#39;);
 ctx.beginPath();
 // Left half
 ctx.moveTo(0, 0);
 ctx.lineTo(canvasWHalf, 0);
 ctx.lineTo(304 + xoff, 97 + yoff);
 ctx.bezierCurveTo(282 + xoff, -5 + yoff, 80 + xoff, -6 + yoff, 76 + xoff, 165 + yoff);
 ctx.bezierCurveTo(74 + xoff, 251 + yoff, 184 + xoff, 300 + yoff, 304 + xoff, 447 + yoff);
 ctx.lineTo(canvasWHalf, canvasH);
 ctx.lineTo(0, canvasH);
 // Right half
 ctx.moveTo(canvasW, 0);
 ctx.lineTo(canvasWHalf, 0);
 ctx.lineTo(304 + xoff, 97 + yoff);
 ctx.bezierCurveTo(326 + xoff, 5 + yoff, 528 + xoff, 6 + yoff, 532 + xoff, 165 + yoff);
 ctx.bezierCurveTo(534 + xoff, 251 + yoff, 424 + xoff, 300 + yoff, 304 + xoff, 447 + yoff);
 ctx.lineTo(canvasWHalf, canvasH);
 ctx.lineTo(canvasW, canvasH);
 ctx.closePath();
 ctx.fill();
 // Raindrops
 for (var i = 1; i < id; i++) {
  raindrops[i].fall();
 };
 }
 var Raindrop = function() {
 id++;
 this.y = random(-canvasH);
 this.x = random(canvasW);
 this.size = random(minSize, maxSize);
 this.speed = random(minSpeed, maxSpeed);
 this.color = &#39;hsl(&#39; + random(minHue, maxHue) + &#39;,100%,55%)&#39;;
 this.origColor = this.color;
 this.id = id;
 raindrops[id] = this;
 };
 Raindrop.prototype.fall = function() {
 this.y += this.speed;
 if (this.y >= canvasH) {
  this.y = random(-canvasH);
  this.x = random(canvasW);
 }
 ctx.save();
 ctx.beginPath();
 var gradient = ctx.createRadialGradient(this.x, this.y, 0, this.x, this.y, this.size);
 gradient.addColorStop(0, &#39;#fff&#39;);
 gradient.addColorStop(0.5, this.color);
 gradient.addColorStop(1, hexToRGB(bg, 0));
 ctx.rect(this.x, this.y, this.size, maxSpeed);
 ctx.fillStyle = gradient;
 ctx.fill();
 ctx.closePath();
 ctx.restore();
 };
 (function init() {
 ctx.fillStyle = &#39;#&#39; + bg;
 ctx.fillRect(0, 0, canvasW, canvasH);
 for (var i = 0; i < maxAmount; i++) {
  new Raindrop();
 }
 }());
 function animate() {
 draw();
 window.requestAnimationFrame(animate);
 }
 window.requestAnimationFrame(animate);
 function mouseTrail(x, y) {
 ctx.save();
 ctx.globalCompositeOperation = &#39;overlay&#39;;
 ctx.fillStyle = &#39;rgba(255,255,255,0.1)&#39;;
 ctx.arc(x, y, 50, 0, Math.PI * 2);
 ctx.fill();
 ctx.restore();
 }
 window.addEventListener(&#39;mousemove&#39;, function(cursor) {
 mouseTrail(cursor.x, cursor.y);
 });
 </script>
 </body>
</html>

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