我正在尝试将此 Popmotion 示例转换为 GreenSock。

https://codepen.io/popmotion/pen/xVeWmm

var SELECTOR      = '.box';
var velocityRange = [-1000, 1000];
var maxRotate     = 30;
var smoothing     = 100;

var box = ui.select(SELECTOR, {
    values: {
        x: 0,
        y: 0,
        rotateY: {
            watch: function (actor) {
                return actor.values.x.velocity;
            },
            mapFrom: velocityRange,
            mapTo: [-maxRotate, maxRotate],
            smooth: smoothing
        },
        rotateX: {
            watch: function (actor) {
                return actor.values.y.velocity;
            },
            mapFrom: velocityRange,
            mapTo: [maxRotate, -maxRotate],
            smooth: smoothing
        }
    }
});

var track2D = new ui.Track({
    values: {
        x: {},
        y: {}
    }
});

var springBack = new ui.Simulate({
    simulate: 'spring',
    spring: 500,
    friction: 0.3,
    values: {
        x: 0,
        y: 0
    }
});

$('body').on('touchstart mousedown', SELECTOR, function (e) {

    e.preventDefault();        
    box.start(track2D, e);

});

$('body').on('touchend mouseup', function () {

    box.start(springBack);

});

作为 GreenSock 的菜鸟，这很容易做到吗？ GreenSock 有 Actor 和模拟器吗？

最佳答案

我从来没有用过GreenSock来制作连续的动态动画(也许有可能，我不是GreenSock方面的专家)。我更喜欢离开这个库来制作特定的动画。在下一个示例中，我尝试使用我自己的计算复制您发布的相同 Popmotion 效果，我只是使用动画库将盒子返回到其原始位置。我认为它可以帮助您实现目标:

I've removed the vendor prefixes to make the code easier to read, but the CodePen example has the prefixes.

HTML 代码:

<div id="container">

  <div class="box"></div>

</div>

CSS 代码

html {
    height: 100%;
}

body {
    background: #e25875;
    height: 100%;
}

#container {
    height: 100%;
    perspective: 700;
    perspective-origin: 50% 50%;
    position: relative;
    transform-style: preserve-3d;
    width: 100%;
}

.box {
    background: white;
    border-radius: 4px;
    height: 150px;
    left: 50%;
    margin-left: -75px;
    margin-top: -75px;
    position: absolute;
    cursor: pointer;
    top: 50%;
    will-change: transform;
    width: 150px;
}

JavaScript 代码:

//---Variables
var doc = document,
    box = doc.querySelector(".box"),
    startX = 0,
    startY = 0,
    posX = 0,
    posY = 0,
    speedX = 0,
    speedY = 0,
    obj = {x: 0, y: 0, speedX: 0, speedY: 0};

//---Main Events
box.addEventListener("mousedown", startMove);
doc.addEventListener("mouseup", stopMove);

//---Start the movement
function startMove (evt) {

    startX = evt.pageX;
    startY = evt.pageY;

    //---Add the mouse move events
    doc.addEventListener("mousemove", updatePosition);

}

//---Update variables
function updatePosition (evt) {

    speedX = (evt.pageX - posX) * 5;
    speedY = (evt.pageY - posY) * 5;

    if (speedX < -45) { speedX = -45 }
    if (speedX > 45) { speedX = 45 }
    if (speedY < -45) { speedY = -45 }
    if (speedY > 45) { speedY = 45 }

    posX = evt.pageX;
    posY = evt.pageY;

    obj.x += (posX - startX - obj.x) * .15;
    obj.y += (posY - startY - obj.y) * .15;
    obj.speedX += (speedX - obj.speedX) * .15;
    obj.speedY += (speedY - obj.speedY) * .15; 

    updateTransform();

}

//---Stop movement, returns the box to its place
function stopMove () {

    TweenLite.to(obj, 0.75, {
        ease: Elastic.easeOut.config(1, 0.3),
        x: 0,
        y: 0,
        speedX: 0,
        speedY: 0,
        onUpdate: updateTransform
    });

    doc.removeEventListener("mousemove", updatePosition);

}

//---Update the box transformations
function updateTransform () {

    var transformStr = "translate(" + obj.x + "px, " + obj.y + "px) rotateX(" + (-obj.speedY) + "deg) rotateY(" + obj.speedX + "deg)";

    box.style.transform = transformStr;

}

这里有一个带有工作示例的 CodePen。

编辑:我更新了 CodePen 以使用 Touch Events。

CodePen

关于javascript - 将 Popmotion 示例转换为 GreenSock，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/35401503/