线条相关动画案例

带遮罩效果的图片展示动画：鼠标hover动画显示遮罩和线

 -> 

<div class="img-wrap">
	<div class="mask">
		<h1>NCT DREAM</h1>
		<p>MARK RENJUN HEACHAN JENO JEAMIN CHENLE JISUNG</p>
	</div>
	<img src="10.jpg" />
</div>

四条线用伪类做

div {
	box-sizing: border-box;
}
img {
	width: 100%;
}
.img-wrap {
	position: relative;
	width: 600px;
	height: 406px;
	margin: 100px auto;
}
.img-wrap .mask {
	position: absolute;
	top: 0;
	left: 0;
	width: 100%;
	height: 100%;
	background-color: rgba(0, 0, 0, .5);
	color: #fff;
	text-align: center;
	padding-top: 150px;
	line-height: 100px;
	opacity: 0;
	transition: opacity .3s;
}
.img-wrap::before,
.img-wrap::after,
.img-wrap .mask::before,
.img-wrap .mask::after {
	content: '';
	display: block;
	position: absolute;
	z-index: 1;
	transition: all .3s;
}
.img-wrap::before,
.img-wrap::after {
	width: 100%;
	height: 0;
	opacity: 0;
}
.img-wrap .mask::before,
.img-wrap .mask::after {
	width: 0;
	height: 100%;
}
.img-wrap::before {
	border-top: 1px solid #fff;
	top: 0;
	left: 0;
}
.img-wrap::after {
	border-bottom: 1px solid #fff;
	bottom: 0;
	left: 0;
}
.img-wrap .mask::before {
	border-left: 1px solid #fff;
	left: 0;
	top: 0;
}
.img-wrap .mask::after {
	border-right: 1px solid #fff;
	right: 0;
	top: 0;
}
.img-wrap:hover .mask {
	opacity: 1;
}
.img-wrap:hover::before {
	opacity: 1;
	top: 50px;
}
.img-wrap:hover::after {
	opacity: 1;
	bottom: 50px;
}
.img-wrap:hover .mask::before {
	left: 50px;
}
.img-wrap:hover .mask::after {
	right: 50px;
}

盒子聚焦效果：hover火箭旋转，阴影增加，线条聚集

 -> 

四条线从四周起始，从0变为边框长度，向内运动聚焦

<div class="card">
	<span class="line left-line"></span>
	<span class="line right-line"></span>
	<span class="line top-line"></span>
	<span class="line bottom-line"></span>
	<div class="img-box">
		<img src="n.jpg" />
	</div>
	<div class="content-box">
		<h2>NCT</h2>
		<h3>Neo Culture Technology</h3>
		<p>NCT127 NCTdream WayV</p>
	</div>
</div>

body {
	background-color: #252a30;
}
div {
	box-sizing: border-box;
}
img {
	width: 100%;
}
.card {
	position: relative;
	width: 400px;
	height: 200px;
	box-shadow: 0 0 3px #b1db56;
	margin: 300px auto;
	cursor: pointer;
	transition: box-shadow .3s;
}
.card div {
	float: left;
}
.card .img-box {
	width: 200px;
	height: 200px;
	padding: 35px;
}
.card .img-box img {
	transition: transform .3s;
}
.card .content-box {
	width: 200px;
	height: 200px;
	text-align: center;
}
.card .content-box h2,
.card .content-box h3 {
	color: #b1db56;
}
.card .content-box p {
	color: #ccc;
}
.card .line {
	position: absolute;
	display: block;
	color: #b1db56;
	transition: all .3s;
	width: 0;
	height: 0;
}
/*线从右边进去*/
.card .line.top-line {
	top: -1px;
	right: -250px;
	border-top: 1px solid #b1db56;
}
.card .line.bottom-line {
	bottom: -1px;
	left: -250px;
	border-bottom: 1px solid #b1db56;
}
.card .line.left-line {
	left: -1px;
	top: -150px;
	border-left: 1px solid #b1db56;
}
.card .line.right-line {
	right: -1px;
	bottom: -150px;
	border-right: 1px solid #b1db56;
}
.card:hover {
	box-shadow: 0 0 15px #b1db56;
}
.card:hover .img-box img {
	transform: rotate(360deg);
}
/*hover的时候线的宽或高恢复成盒子的边框长度*/
.card:hover .line.top-line,
.card:hover .line.bottom-line {
	width: 399px;
}
.card:hover .line.left-line,
.card:hover .line.right-line {
	height: 199px;
}
/*位置也恢复到边框位置*/
.card:hover .line.top-line {
	right: 0;
}
.card:hover .line.bottom-line {
	left: 0;
}
.card:hover .line.left-line {
	top: 0;
}
.card:hover .line.right-line {
	bottom: 0;
}