JavaScript实现的抛物线运动效果

ゝ一世哀愁。 2022-08-06 14:07 156阅读 0赞

原文：[http://www.css88.com/archives/5355][http_www.css88.com_archives_5355]

作者的主要实现代码：

;
    (function () {
        var _$ = function (_this) {
            return _this.constructor == jQuery ? _this : $(_this);
        };
    // 获取当前时间
        function now() {
            return +new Date();
        }
     
    // 转化为整数
        function toInteger(text) {
            text = parseInt(text);
            return isFinite(text) ? text : 0;
        }
     
        var Parabola = function (options) {
            this.initialize(options);
        };
        Parabola.prototype = {
            constructor: Parabola,
            /**
             * 初始化
             * @classDescription 初始化
             * @param {Object} options 插件配置 .
             */
            initialize: function (options) {
                this.options = this.options || this.getOptions(options);
                var ops = this.options;
                if (!this.options.el) {
                    return;
                }
                this.$el = _$(ops.el);
                this.timerId = null;
                this.elOriginalLeft = toInteger(this.$el.css("left"));
                this.elOriginalTop = toInteger(this.$el.css("top"));
                // this.driftX X轴的偏移总量
                //this.driftY Y轴的偏移总量
                if (ops.targetEl) {
                    this.driftX = toInteger(_$(ops.targetEl).css("left")) - this.elOriginalLeft;
                    this.driftY = toInteger(_$(ops.targetEl).css("top")) - this.elOriginalTop;
                } else {
                    this.driftX = ops.offset[0];
                    this.driftY = ops.offset[1];
                }
                this.duration = ops.duration;
                // 处理公式常量
                this.curvature = ops.curvature;
                // 根据两点坐标以及曲率确定运动曲线函数（也就是确定a, b的值）
                //a=this.curvature
                /* 公式： y = a*x*x + b*x + c;
                 */
                /*
                 * 因为经过(0, 0), 因此c = 0
                 * 于是：
                 * y = a * x*x + b*x;
                 * y1 = a * x1*x1 + b*x1;
                 * y2 = a * x2*x2 + b*x2;
                 * 利用第二个坐标：
                 * b = (y2+ a*x2*x2) / x2
                 */
                // 于是
                this.b = ( this.driftY - this.curvature * this.driftX * this.driftX ) / this.driftX;
     
                //自动开始
                if (ops.autostart) {
                    this.start();
                }
            },
            /**
             * 初始化 配置参数 返回参数MAP
             * @param {Object} options 插件配置 .
             * @return {Object} 配置参数
             */
            getOptions: function (options) {
                if (typeof options !== "object") {
                    options = {};
                }
                options = $.extend({}, defaultSetting, _$(options.el).data(), (this.options || {}), options);
     
                return options;
            },
            /**
             * 定位
             * @param {Number} x x坐标 .
             * @param {Object} y y坐标 .
             * @return {Object} this
             */
            domove: function (x, y) {
     
                this.$el.css({
                    position: "absolute",
                    left: this.elOriginalLeft + x,
                    top: this.elOriginalTop + y
                });
     
                return this;
            },
            /**
             * 每一步执行
             * @param {Data} now 当前时间 .
             * @return {Object} this
             */
            step: function (now) {
                var ops = this.options;
                var x, y;
                if (now > this.end) {
                    // 运行结束
                    x = this.driftX;
                    y = this.driftY;
                    this.domove(x, y);
                    this.stop();
                    if (typeof ops.callback === 'function') {
                        ops.callback.call(this);
                    }
                } else {
                    //x 每一步的X轴的位置
                    x = this.driftX * ((now - this.begin) / this.duration);
                    //每一步的Y轴的位置y = a*x*x + b*x + c;   c==0;
                    y = this.curvature * x * x + this.b * x;
     
                    this.domove(x, y);
                    if (typeof ops.stepCallback === 'function') {
                        ops.stepCallback.call(this);
                    }
                }
                return this;
            },
            /**
             * 设置options
             *  @param {Object} options 当前时间 .
             */
            setOptions: function (options) {
                this.reset();
                if (typeof options !== "object") {
                    options = {};
                }
                this.options = this.getOptions(options);
                this.initialize('parabola', this.options);
                return this;
            },
            /**
             * 开始
             */
            start: function () {
                var self = this;
                // 设置起止时间
                this.begin = now();
                this.end = this.begin + this.duration;
                if (this.driftX === 0 && this.driftY === 0) {
                    // 原地踏步就别浪费性能了
                    return;
                }
                /*timers.push(this);
                 Timer.start();*/
                if (!!this.timerId) {
                    clearInterval(this.timerId);
                    this.stop();
                }
                this.timerId = setInterval(function () {
                    var t = now();
                    self.step(t);
     
                }, 13);
                return this;
            },
            /**
             * 重置
             */
            reset: function (x, y) {
                this.stop();
                x = x ? x : 0;
                y = y ? y : 0;
                this.domove(x, y);
                return this;
            },
            /**
             * 停止
             */
            stop: function () {
                if (!!this.timerId) {
                    clearInterval(this.timerId);
     
                }
                return this;
            }
        };
        var defaultSetting = {
            el: null,
            //偏移位置
            offset: [0, 0],
            //终点元素，这时就会自动获取该元素的left、top，设置了这个参数，offset将失效
            targetEl: null,
            //运动的时间，默认500毫秒
            duration: 500,
            //抛物线曲率，就是弯曲的程度，越接近于0越像直线，默认0.001
            curvature: 0.001,
            //运动后执行的回调函数
            callback: null,
            // 是否自动开始，默认为false
            autostart: false,
            //运动过程中执行的回调函数
            stepCallback: null
        };
        window.Parabola = Parabola;
    })();

使用：

demo地址： [http://www.css88.com/demo/parabola/index.html][http_www.css88.com_demo_parabola_index.html]  
demo内容：

<!DOCTYPE HTML>
    <html>
    <head>
        <meta charset="utf-8">
        <title>抛物线运动效果</title>
        <style type="text/css">
            .boll {
                width: 50px;
                height: 50px;
                background-color: #ff3333;
                position: absolute;
                top: 380px;
                left: 100px;
                -moz-border-radius: 50px;
                -webkit-border-radius: 50px;
                border-radius: 50px;
            }
    
            .target {
                width: 50px;
                height: 50px;
                background-color: #CDCDCD;
                position: absolute;
                top: 180px;
                left: 600px;
                -moz-border-radius: 50px;
                -webkit-border-radius: 50px;
                border-radius: 50px;
            }
        </style>
        <script type="text/javascript" src="http://www.css88.com/jqapi-1.9/js/jquery.min.js"></script>
        <script type="text/javascript" src="js/parabola.js"></script>
    </head>
    
    <body>
    <div class="btns" style="margin-top:20px">
        <a href="http://www.css88.com/archives/5355" target="_blank">回到JavaScript实现的抛物线运动效果</a>
    </div>
        <div class="btns" style="margin-top:20px">
        <a href="#" class="btnA btn-danger" id="reset" rel="popover" title="A Title" style="">reset</a>
        <a href="#" class="btnA btn-danger" id="run" rel="popover" title="A Title" style="">run</a>
        <a href="#" class="btnA btn-danger" id="stop" rel="popover" title="A Title" style="">stop</a>
        <a href="#" class="btnA btn-danger" id="setOptions" rel="popover" title="A Title" style="">setOptions</a>
    </div>
    <div id="boll" class="boll"></div>
    <div id="target" class="target"></div>
    <script type="text/javascript">
        var bool = new Parabola({
            el: "#boll",
            offset: [500, 100],
            curvature: 0.005,
            duration: 3000,
            callback:function(){
                alert("完成后回调")
            },
            stepCallback:function(x,y){
                console.log(x,y);
                $("<div>").appendTo("body").css({
                    "position": "absolute",
                    "top": this.elOriginalTop + y,
                    "left":this.elOriginalLeft + x,
                    "background-color":"#CDCDCD",
                    "width":"5px",
                    "height":"5px",
                    "border-radius": "5px"
                });
            }
        });
        $("#reset").click(function (event) {
            event.preventDefault();
            bool.reset()
        });
        $("#run").click(function (event) {
            event.preventDefault();
            bool.start();
        });
        $("#stop").click(function (event) {
            event.preventDefault();
            bool.stop();
        });
        $("#setOptions").click(function (event) {
            event.preventDefault();
            bool.setOptions({
                targetEl: $("#target"),
                curvature: 0.001,
                duration: 1000
            });
        });
    </script>
    </body>
    </html>

另外一个仿天猫的抛物线效果，原作者地址： [https://github.com/amibug/fly][https_github.com_amibug_fly]  
demo:  [http://codepen.io/hzxs1990225/full/ogLaVp][http_codepen.io_hzxs1990225_full_ogLaVp]

**IE10以下，引入src/requestAnimationFrame.js**

[http_www.css88.com_archives_5355]: http://www.css88.com/archives/5355
[http_www.css88.com_demo_parabola_index.html]: http://www.css88.com/demo/parabola/index.html
[https_github.com_amibug_fly]: https://github.com/amibug/fly
[http_codepen.io_hzxs1990225_full_ogLaVp]: http://codepen.io/hzxs1990225/full/ogLaVp