HTML5JSstar_动态星空效果

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HTML5JSstar_动态星空效果

一、案例介绍

这个案例主要运用了html5播放引用的功能。


播放音乐代码如下:

        <audio controls="true" autoplay="autoplay" class="audio">
            <source src="css/Music.mp3" type="audio/mp3"> 
            <source src="css/Music.ogg" type="audio/ogg"> 
            <source src="css/Music.aac" type="audio/mp4"> 
        </audio>


星空效果是用canvas绘制的,代码如下:
 "use strict";
            var canvas = document.getElementById('canvas'),
                    ctx = canvas.getContext('2d'),
                    w = canvas.width = window.innerWidth,
                    h = canvas.height = window.innerHeight,
                    hue = 217,
                    stars = [],
                    count = 0,
                    maxStars = 1300;//星星数量

            var canvas2 = document.createElement('canvas'),
                    ctx2 = canvas2.getContext('2d');
            canvas2.width = 100;
            canvas2.height = 100;
            var half = canvas2.width / 2,
                    gradient2 = ctx2.createRadialGradient(half, half, 0, half, half, half);
            gradient2.addColorStop(0.025, '#CCC');
            gradient2.addColorStop(0.1, 'hsl(' + hue + ', 61%, 33%)');
            gradient2.addColorStop(0.25, 'hsl(' + hue + ', 64%, 6%)');
            gradient2.addColorStop(1, 'transparent');

            ctx2.fillStyle = gradient2;
            ctx2.beginPath();
            ctx2.arc(half, half, half, 0, Math.PI * 2);
            ctx2.fill();

            // End cache

            function random(min, max) {
                if (arguments.length < 2) { max = min; min = 0; } if (min > max) {
                    var hold = max;
                    max = min;
                    min = hold;
                }

                return Math.floor(Math.random() * (max - min + 1)) + min;
            }

            function maxOrbit(x, y) {
                var max = Math.max(x, y),
                        diameter = Math.round(Math.sqrt(max * max + max * max));
                return diameter / 2;
                //星星移动范围,值越大范围越小,
            }

            var Star = function () {

                this.orbitRadius = random(maxOrbit(w, h));
                this.radius = random(60, this.orbitRadius) / 8;
                //星星大小
                this.orbitX = w / 2;
                this.orbitY = h / 2;
                this.timePassed = random(0, maxStars);
                this.speed = random(this.orbitRadius) / 50000;
                //星星移动速度
                this.alpha = random(2, 10) / 10;

                count++;
                stars[count] = this;
            }

            Star.prototype.draw = function () {
                var x = Math.sin(this.timePassed) * this.orbitRadius + this.orbitX,
                        y = Math.cos(this.timePassed) * this.orbitRadius + this.orbitY,
                        twinkle = random(10);

                if (twinkle === 1 && this.alpha > 0) {
                    this.alpha -= 0.05;
                } else if (twinkle === 2 && this.alpha < 1) { this.alpha += 0.05; } ctx.globalAlpha = this.alpha; ctx.drawImage(canvas2, x - this.radius / 2, y - this.radius / 2, this.radius, this.radius); this.timePassed += this.speed; } for (var i = 0; i < maxStars; i++) { new Star(); } function animation() { ctx.globalCompositeOperation = 'source-over'; ctx.globalAlpha = 0.5; //尾巴 ctx.fillStyle = 'hsla(' + hue + ', 64%, 6%, 2)'; ctx.fillRect(0, 0, w, h) ctx.globalCompositeOperation = 'lighter'; for (var i = 1, l = stars.length; i < l; i++) { stars[i].draw(); } ; window.requestAnimationFrame(animation); } animation();


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