canvas实现烟花特效

短命女 2022-03-17 08:27 375阅读 0赞

> 看过我之前博客的人一定都知道我对canvas赞不绝口，没看过？那就看看下面这篇吧，总结一下对canvas的使用心得就是盘它！

实现效果：

![2019022310275268.gif][]

代码如下，注释已写：

<!DOCTYPE html>
    <html lang="en">
    
    <head>
        <meta charset="UTF-8">
        <meta name="viewport" content="width=device-width, initial-scale=1.0">
        <meta http-equiv="X-UA-Compatible" content="ie=edge">
        <title>烟花爆炸动画</title>
        <style>
            body {
                padding: 0;
                margin: 0;
                overflow: hidden;
                background-color: black;
            }
    
            html,
            body {
                width: 100%;
                height: 100%;
            }
        </style>
    </head>
    <canvas id="canvas"></canvas>
    <script>
        var canvas = document.getElementById('canvas'); //获取canvas
        canvas.width = window.innerWidth; //设置画布大小
        canvas.height = window.innerHeight;
        var content2d = canvas.getContext('2d'); //转化为2d模式
        var balls = []; //建立数组用于存放小球
    
        function ball() { //构造函数方法开发
            this.color = null; //分别为小球的颜色，x y坐标，半径，角度，角度移动x，y坐标
            this.x = null;
            this.y = null;
            this.r = null;
            this.Angle = null;
            this.Anglex = null;
            this.Angley = null;
            this.init = function (x, y) {
                // 初始化状态
                this.x = x;
                this.y = y;
                this.r = this.randomNum(15, 25);
                this.color = this.randomColor();
                this.Angle = Math.random() * Math.PI * 2;
                this.Anglex = this.randomNum(10, 12) * Math.cos(this.Angle); //利用三角函数来控制小球的移动方向
                this.Angley = this.randomNum(10, 12) * Math.sin(this.Angle);
            };
            this.randomColor = function () { //随机颜色
                return "#" + parseInt(Math.random() * 16777216).toString(16);
            };
            this.randomNum = function (max, min) { //随机坐标**/*-*-+**
                return Math.random() * max + min;
            };
            this.move = function () {//利用坐标的偏移和半径的减少和重绘来实现小球的移动
                this.x += this.Anglex * 1.1;
                this.y += this.Angley * 1.1;
                this.r -= 0.35;
                this.Anglex *= 0.92;
                this.Angley *= 0.92;
            }
        }
    
        function createBall(x, y) {
            var count = parseInt(Math.random() * 15 + 15);//随机小球数量
            for (var i = 0; i < count; i++) {
                var b = new ball();
                b.init(x, y);
                balls.push(b);
            }
        }
    
        function Draw() {
    
            for (var i = 0; i < balls.length; i++) {
                var b = balls[i];
                b.move();
                content2d.beginPath();
                content2d.fillStyle = b.color;
                content2d.arc(b.x, b.y, b.r, 0, Math.PI * 2);
                content2d.fill();
                content2d.closePath();
                // console.log(1);
            }
        }
    
        function removeBall() {//如果小球的半径小于等值，移除小球
            for (var i = 0; i < balls.length; i++) {
                var b = balls[i];
                if (b.r < 0.35) {
                    balls.splice(i, 1);
                    i--;
                }
            }
        }
        loop();
    
        function loop() {//（重绘）h5 计时器，强大好用
            // 清除整个canvas
            content2d.clearRect(0, 0, canvas.width, canvas.height);
            Draw();
            removeBall();
            // console.log(1);
            window.requestAnimationFrame(loop);
        }
        canvas.onclick = function (e) {
            var x = e.pageX;
            var y = e.pageY;
            // console.log(x);
            createBall(x, y);
        }
    </script>
    
    <body>
    
    </body>
    
    </html>

[2019022310275268.gif]: /images/20220317/6dd9d5c7ffd342319e5d22f3b2aafd4f.png