如何用纯 CSS 创作一个赛车 loader

末蓝、 2022-04-06 05:22 210阅读 0赞

![在这里插入图片描述][20181208132650844.gif]

## 效果预览 ##

[在线演示][Link 1]

按下右侧的“点击预览”按钮可以在当前页面预览，点击链接可以全屏预览。

[https://codepen.io/comehope/pen/mGdXGJ][https_codepen.io_comehope_pen_mGdXGJ]

## 可交互视频 ##

此视频是可以交互的，你可以随时暂停视频，编辑视频中的代码。

请用 chrome, safari, edge 打开观看。

[https://scrimba.com/p/pEgDAM/c3qL7Sz][https_scrimba.com_p_pEgDAM_c3qL7Sz]

## 源代码下载 ##

[本地下载][Link 2]

每日前端实战系列的全部源代码请从 github 下载：

[https://github.com/comehope/front-end-daily-challenges][https_github.com_comehope_front-end-daily-challenges]

## 代码解读 ##

定义 dom，容器中包含 1 个 `.car` 元素，它的 2 个子元素分别代表车身和车轮：

居中显示：

body {
        margin: 0;
        height: 100vh;
        display: flex;
        align-items: center;
        justify-content: center;
        background-color: #333;
    }

定义容器尺寸和车的颜色：

.loader {
        width: 11.7em;
        height: 4.2em;
        color: lightcyan;
        position: relative;
    }

画出底盘：

.car {
        position: absolute;
        width: inherit;
        height: 2em;
        background-color: currentColor;
        top: 1.5em;
        border-radius: 0 5em 1em 0 / 0 4em 1em 0;
    }

画出尾冀：

.car::before {
        content: '';
        position: absolute;
        width: 0;
        height: 0;
        border: 0.6em solid transparent;
        border-left-width: 0;
        border-right-color: currentColor;
        transform-origin: left;
        transform: rotate(-45deg);
        top: -0.5em;
    }

（这时看起来有点儿像飞机，哈哈~~）

画出车身：

.body {
        position: absolute;
        width: 7.5em;
        height: 3.5em;
        box-sizing: border-box;
        border: 0.4em solid;
        border-radius: 3em 4.5em 0 0 / 3em 4em 0 0;
        top: -1.5em;
        left: 1.2em;
    }

用伪元素画出车窗：

.body::before {
        content: '';
        position: absolute;
        width: 3.5em;
        height: inherit;
        background-color: currentColor;
        border-top-left-radius: inherit;
        left: -0.4em;
        top: -0.4em;
    }

画出车轮的轮廓：

.wheels::before,
    .wheels::after {
        content: '';
        position: absolute;
        box-sizing: border-box;
        width: 2.6em;
        height: 2.6em;
        background-color: #333;
        border-radius: 50%;
        bottom: -1em;
    }

画出轮毂：

.wheels::before,
    .wheels::after {
        border: 0.3em solid #333;
        background-image: 
            linear-gradient(
                135deg,
                transparent 45%,
                currentColor 46%, currentColor 54%,
                transparent 55%
            ),
            linear-gradient(
                90deg,
                transparent 45%,
                currentColor 46%, currentColor 54%,
                transparent 55%
            ),
            linear-gradient(
                45deg,
                transparent 45%,
                currentColor 46%, currentColor 54%,
                transparent 55%
            ),
            linear-gradient(
                0deg,
                transparent 45%,
                currentColor 46%, currentColor 54%,
                transparent 55%
            ),
            radial-gradient(
                currentColor 29%,
                transparent 30%, transparent 50%,
                currentColor 51%
            );
    }

把车轮定位到左右两侧：

.wheels::before {
        left: 1.2em;
    }
    
    .wheels::after {
        right: 0.8em;
    }

接下来制作动画效果。

增加表示风影的 dom 元素 `.strikes`，它包含 5 个子元素：

画出 5 段短细线：

.strikes {
        position: absolute;
        width: 1em;
        height: inherit;
        border: 1px dashed white;
        display: flex;
        flex-direction: column;
        justify-content: space-between;
    }
    
    .strikes span {
        height: 0.1em;
        background-color: lightcyan;
    }

增加风影飘逝的动画效果，定义 css 变量，设置动画延时：

.strikes span {
        animation: drift 0.2s linear infinite;
        animation-delay: calc((var(--n) - 1) * 0.05s);
    }
    
    @keyframes drift {
        from {
            transform: translate(3.5em);
        }
    
        to {
            transform: translate(-8em);
            filter: opacity(0);
        }
    }
    
    .strikes span:nth-child(1) {
        --n: 1;
    }
    
    .strikes span:nth-child(2) {
        --n: 2;
    }
    
    .strikes span:nth-child(3) {
        --n: 3;
    }
    
    .strikes span:nth-child(4) {
        --n: 4;
    }
    
    .strikes span:nth-child(5) {
        --n: 5;
    }

增加轮子转动动画效果：

.wheels::before,
    .wheels::after {
        animation: rotating 0.5s linear infinite;
    }
    
    @keyframes rotating {
        to {
            transform: rotate(1turn);
        }
    }

增加车身颠簸的动画效果：

.car {
        animation: run 0.25s linear infinite;
    }
    
    @keyframes run {
        0% {
            transform: translate(0.2em, 0.1em) rotate(0deg);
        }
    
        20% {
            transform: translate(0.1em, 0.2em) rotate(1deg);
        }
    
        40% {
            transform: translate(0.1em, -0.1em) rotate(-1deg);
        }
    
        60% {
            transform: translate(-0.1em, 0.2em) rotate(0deg);
        }
    
        80% {
            transform: translate(-0.1em, 0.1em) rotate(1deg);
        }
    
        100% {
            transform: translate(0.2em, 0.1em) rotate(-1deg);
        }
    }

大功告成！

原文地址：https://segmentfault.com/a/1190000016087024

[20181208132650844.gif]: /images/20220406/dbab8b4d3e2a46a88b696c90511750a5.png
[Link 1]: https://www.jqhtml.com/yanshi?demourl=%2Fwp-content%2Fuploads%2F2018%2F11%2Ffront-end-daily-challenges-master%2F113-racing-car-loader&demotitle=%E7%BA%AF%20CSS%20%E5%88%9B%E4%BD%9C%E4%B8%80%E4%B8%AA%E8%B5%9B%E8%BD%A6%20loader
[https_codepen.io_comehope_pen_mGdXGJ]: https://codepen.io/comehope/pen/mGdXGJ
[https_scrimba.com_p_pEgDAM_c3qL7Sz]: https://scrimba.com/p/pEgDAM/c3qL7Sz
[Link 2]: http://www.jqhtml.com/21061.html
[https_github.com_comehope_front-end-daily-challenges]: https://github.com/comehope/front-end-daily-challenges