纯css3卡通小火车行驶动画

效果展示

HTML代码

<div class="center">
    <div class="mountains"></div>
    <div class="train">
        <div class="engine-front">
            <div class="chimney">
                <div class="smoke"></div>
                <div class="smoke smoke-2"></div>
                <div class="smoke smoke-3"></div>
                <div class="smoke smoke-4"></div>
            </div>
        </div>
        
        <div class="engine-body"></div>
        
        <div class="compartment">
            <div class="compartment-window"></div>
        </div>
        
        <div class="compartment compartment-two">
            <div class="compartment-window"></div>
        </div>
        
        <div class="compartment compartment-three">
            <div class="compartment-window"></div>
        </div>
        
        <div class="wheel-holder">
            <div class="wheel"></div>
            <div class="wheel wheel-2">
                <div class="wheel-joint"></div>
                <div class="wheel-joint wheel-joint-2"></div>
            </div>
            <div class="wheel wheel-3"></div>
            <div class="wheel wheel-4"></div>
            <div class="wheel wheel-5"></div>
            <div class="wheel wheel-6"></div>
            <div class="wheel wheel-7"></div>
            <div class="wheel wheel-8"></div>
            <div class="wheel wheel-9"></div>
        </div>
    </div>
    <div class="bridge"></div>
</div>

HTML代码的结构非常清晰，总体来讲分两部分，一部分是作为背景的明月、高山以及星空，对应的CSS类为mountains；另一部分则是行驶的火车，对应的CSS类为train。

对于火车部分则相对比较复杂，有车头、引擎、轨道、车轮、车厢等元素，下面的CSS代码中会一一讲解。

CSS代码

背景部分绘制了两座高山，一轮明月以及清澈的星空。

.mountains {
    height: 100%;
    position: absolute;
    width: 100%;
    z-index: 1;
}
.mountains::before, .mountains::after {
    background: #000c18;
    background: -moz-linear-gradient(#012a53, #000c18 50%);
    background: -webkit-linear-gradient(#012a53, #000c18 50%);
    background: -o-linear-gradient(#012a53, #000c18 50%);
    background: -ms-linear-gradient(#012a53, #000c18 50%);
    background: linear-gradient(#012a53, #000c18 50%);
    content: "";
    height: 100%;
    position: absolute;
}
.mountains::before {
    border-radius: 100% 300% 0 0;
    left: -20%;
    width: 57%;
}
.mountains::after {
    border-radius: 300% 100% 0 0;
    right: -20%;
    width: 80%;
}
然后就是火车轨道的桥梁部分，也十分简单。

.bridge {
    border-bottom: 0.3rem solid white;
    border-top: 0.3rem solid white;
    background: black;
    background: -webkit-linear-gradient(55deg, transparent 46%, white 46%, white 54%, transparent 54%) left/1.6rem 2.2rem, -webkit-linear-gradient(-55deg, transparent 46%, white 46%, white 54%, transparent 54%) left/1.6rem 2.2rem;
    background: -moz-linear-gradient(55deg, transparent 46%, white 46%, white 54%, transparent 54%) left/1.6rem 2.2rem, -moz-linear-gradient(-55deg, transparent 46%, white 46%, white 54%, transparent 54%) left/1.6rem 2.2rem;
    background: -o-linear-gradient(55deg, transparent 46%, white 46%, white 54%, transparent 54%) left/1.6rem 2.2rem, -o-linear-gradient(-55deg, transparent 46%, white 46%, white 54%, transparent 54%) left/1.6rem 2.2rem;
    background: -ms-linear-gradient(55deg, transparent 46%, white 46%, white 54%, transparent 54%) left/1.6rem 2.2rem, -ms-linear-gradient(-55deg, transparent 46%, white 46%, white 54%, transparent 54%) left/1.6rem 2.2rem;
    background: linear-gradient(55deg, transparent 46%, white 46%, white 54%, transparent 54%) left/1.6rem 2.2rem, linear-gradient(-55deg, transparent 46%, white 46%, white 54%, transparent 54%) left/1.6rem 2.2rem;
    bottom: 10rem;
    height: 2.6rem;
    position: absolute;
    width: 100%;
    z-index: 1;
}
在后面就是本动画的主体部分小火车了，其每一部分都有对应的CSS类来描述，请看代码：

.train {
    animation: move-train 24s linear infinite;
    bottom: 12.6rem;
    height: 10rem;
    position: absolute;
    left: calc(100% + 1.3rem);
    width: 44rem;
    z-index: 1;
}

.engine-front, .engine-front::before, .engine-front::after {
    background: #0f0f0f;
    background: linear-gradient(0deg, #0f0f0f, #262626, #0f0f0f);
    border: 0.1rem solid rgba(255, 255, 255, 0.15);
    border-radius: 50% 0 0 50%;
    border-right: none;
}

.engine-front {
    animation: body-upDown 0.3s infinite;
    border-radius: 0.5rem 0 0 0.5rem;
    bottom: 1.4rem;
    height: 4.6rem;
    left: 0;
    position: absolute;
    width: 8rem;
}
.engine-front::before, .engine-front::after {
    content: "";
    position: absolute;
    height: 70%;
    left: -0.9rem;
    top: 50%;
    transform: translate(0, -50%);
    width: 0.8rem;
}
.engine-front::after {
    height: 40%;
    left: -1.4rem;
    width: 0.5rem;
}

.chimney {
    background: #990000;
    height: 2.2rem;
    left: 2.5rem;
    position: absolute;
    top: -2.3rem;
    width: 1.7rem;
}
.chimney::before, .chimney::after {
    content: "";
    position: absolute;
}
.chimney::before {
    animation: up-down 0.3s infinite;
    border-bottom: none;
    border-left: 0.5rem solid transparent;
    border-right: 0.5rem solid transparent;
    border-top: 0.8rem solid orange;
    left: 50%;
    top: -0.9rem;
    transform: translate(-50%, 0);
    width: 160%;
}

.smoke {
    animation: move-smoke 0.4s linear infinite;
    background: rgba(255, 255, 255, 0.8);
    border-radius: 50%;
    height: 1.4rem;
    left: 0.2rem;
    position: absolute;
    top: -1.5rem;
    width: 0.8rem;
    z-index: -1;
}
.smoke-2 {
    animation-delay: 0.1s;
    left: 0.4rem;
}
.smoke-3 {
    animation-delay: 0.2s;
    left: 0.6rem;
}
.smoke-4 {
    left: 0.8rem;
}

.engine-body {
    animation: body-upDown 0.3s 0.1s infinite;
    background: #b30000;
    background: linear-gradient(0deg, #330000, red, #990000);
    border-radius: 0 0 0.4rem 0;
    bottom: 1.4rem;
    height: 7rem;
    left: 8rem;
    position: absolute;
    width: 5rem;
}
.engine-body::before, .engine-body::after {
    content: "";
    left: 50%;
    position: absolute;
    transform: translate(-50%, 0);
}
.engine-body::before {
    animation: up-down 0.3s 0.2s infinite;
    background: #660000;
    background: linear-gradient(0deg, #660000, #990000, #660000);
    border-radius: 50% 50% 0 0;
    height: 1.2rem;
    top: -1.2rem;
    width: 130%;
}
.engine-body::after {
    background: #b3e0f2;
    border-radius: 0.2rem;
    height: 40%;
    top: 1rem;
    width: 45%;
}

.wheel::before, .wheel::after {
    left: 50%;
    top: 50%;
    transform: translate(-50%, -50%);
}

.wheel-holder {
    height: 2.8rem;
    bottom: 0;
    position: absolute;
    width: 100%;
}

.wheel {
    animation: rotate 2s linear infinite;
    background: orange;
    border: 0.3rem solid rgba(0, 0, 0, 0.6);
    border-radius: 50%;
    height: 2.8rem;
    left: 1rem;
    position: absolute;
    width: 2.8rem;
}
.wheel-2 {
    left: 4.5rem;
}
.wheel-3 {
    border-width: 0.5rem;
    height: 3.8rem;
    left: 8.7rem;
    top: -1.1rem;
    width: 3.8rem;
}
.wheel-4 {
    left: 15.7rem;
}
.wheel-5 {
    left: 19.5rem;
}
.wheel-6 {
    left: 25.7rem;
}
.wheel-7 {
    left: 29.5rem;
}
.wheel-8 {
    left: 35.7rem;
}
.wheel-9 {
    left: 39.5rem;
}
.wheel::before, .wheel::after {
    content: "";
    position: absolute;
}
.wheel::before {
    background: rgba(0, 0, 0, 0.3);
    height: 86%;
    width: 0.2rem;
}
.wheel::after {
    background: #996300;
    background: -webkit-radial-gradient(circle at center, #b37400 30%, #996300 30%);
    background: -moz-radial-gradient(circle at center, #b37400 30%, #996300 30%);
    background: -o-radial-gradient(circle at center, #b37400 30%, #996300 30%);
    background: -ms-radial-gradient(circle at center, #b37400 30%, #996300 30%);
    background: radial-gradient(circle at center, #b37400 30%, #996300 30%);
    border-radius: 50%;
    height: 40%;
    width: 40%;
}

.compartment {
    animation: body-upDown 0.3s infinite;
    background: #186c8e;
    background: -webkit-linear-gradient(#104b63 50%, #1f8dba);
    background: -moz-linear-gradient(#104b63 50%, #1f8dba);
    background: -o-linear-gradient(#104b63 50%, #1f8dba);
    background: -ms-linear-gradient(#104b63 50%, #1f8dba);
    background: linear-gradient(#104b63 50%, #1f8dba);
    border-radius: 0 0 0.3rem 0.3rem;
    bottom: 1.4rem;
    height: 5rem;
    left: 15rem;
    position: absolute;
    width: 8rem;
}
.compartment-two {
    animation: body-upDown 0.3s 0.1s infinite;
    left: 25rem;
}
.compartment-two .compartment-window::before {
    animation: up-down 0.3s 0.3s infinite;
}
.compartment-three {
    animation: body-upDown 0.3s 0.2s infinite;
    left: 35rem;
}
.compartment-three .compartment-window::before {
    animation: up-down 0.35s infinite;
}
.compartment::before, .compartment::after {
    background: black;
    border: 0.4rem solid transparent;
    bottom: 0.4rem;
    box-shadow: 0 0 0 1px rgba(255, 255, 255, 0.1);
    content: "";
    height: 0.8rem;
    position: absolute;
    width: 0.9rem;
}
.compartment::before {
    border-left: 0.4rem solid rgba(255, 255, 255, 0.3);
    left: -0.9rem;
}
.compartment::after {
    border-right: 0.4rem solid rgba(255, 255, 255, 0.3);
    left: -2rem;
}

.compartment-window {
    background: #1f8dba;
    background: -moz-linear-gradient(90deg, transparent 0.8rem, skyblue 0.8rem) left/2.4rem 100%;
    background: -webkit-linear-gradient(90deg, transparent 0.8rem, skyblue 0.8rem) left/2.4rem 100%;
    background: -o-linear-gradient(90deg, transparent 0.8rem, skyblue 0.8rem) left/2.4rem 100%;
    background: -ms-linear-gradient(90deg, transparent 0.8rem, skyblue 0.8rem) left/2.4rem 100%;
    background: linear-gradient(90deg, transparent 0.8rem, skyblue 0.8rem) left/2.4rem 100%;
    height: 40%;
    position: absolute;
    top: 0.7rem;
    width: 100%;
}
.compartment-window::before, .compartment-window::after {
    content: "";
    position: absolute;
}
.compartment-window::before {
    animation: up-down 0.3s 0.1s infinite;
    background: #104b63;
    border-radius: 50% 50% 0 0;
    height: 0.6rem;
    left: 50%;
    top: -1.4rem;
    transform: translate(-50%, 0);
    width: 110%;
}

到这里为止，我们已经用HTML和CSS代码将整个小火车以及周围的环境都绘制出来了。

那么最重要的一步便是让这辆小火车在桥梁上行驶起来，这就要用到CSS3的一些动画属性了，CSS3的动画帧闪亮登场。

@keyframes up-down {
    0%, 100% {
        transform: translate(-50%, 0);
    }
    50% {
        transform: translate(-50%, -0.3rem);
    }
}
@keyframes rotate {
    100% {
        transform: rotate(-360deg);
    }
}
@keyframes move-train {
    100% {
        transform: translateX(-154rem);
    }
}
@keyframes body-upDown {
    0%, 100% {
        transform: translateY(0);
    }
    100% {
        transform: translateY(-0.2rem);
    }
}
@keyframes move-smoke {
    0% {
        -webkit-filter: blur(0);
        -moz-filter: blur(0);
        -o-filter: blur(0);
        -ms-filter: blur(0);
        filter: blur(0);
        opacity: 1;
    }
    50% {
        -webkit-filter: blur(0.2rem);
        -moz-filter: blur(0.2rem);
        -o-filter: blur(0.2rem);
        -ms-filter: blur(0.2rem);
        filter: blur(0.2rem);
        opacity: 0.6;
        transform: translate(0, -3rem) scale(2);
    }
    100% {
        -webkit-filter: blur(0.3rem);
        -moz-filter: blur(0.3rem);
        -o-filter: blur(0.3rem);
        -ms-filter: blur(0.3rem);
        filter: blur(0.3rem);
        opacity: 0;
        transform: translate(2.5rem, -6rem) scale(3);
    }
}
@keyframes wheel-joint {
    100% {
        transform: rotate(360deg);
    }
}

这些动画中做了几件事情。

第一，让车厢盖子上下拍动，让动画小火车行驶的样子更加逼真。

第二，利用滤镜，非常生动地描绘出了小火车行驶过程中蒸汽机引擎冒出的蒸汽。

第三，让小火车整体在桥梁上周而复始地行驶，车轮也不停的转动。