使用javascript DOM隐藏图像，仅使其在黑色背景上可见

问题描述

[在此处输入图片描述] [1]

我是JS和DOM学习的新手。我正在尝试学习如何使用DOM进行旋转，请按照下面此教程上的链接进行操作。

https://www.npmjs.com/package/react-paginate

我不知道如何隐藏隐藏在灰色背景中的其余部分（不可见），从而解决该问题。非常感谢您的提前帮助。

https://morioh.com/p/8ae9a2ad64a7?fbclid=IwAR0nTt-eix7NIUXsnYcWezZpXGj_EOughWVZ-0Xd4XdeHha_yhZsn2wW9IQ [2]：https://samuelng87.github.io/ns-pet-switch/

解决方法

您可以尝试以下方法：

用<div id="circle">元素包装<div id="clip">元素 赋予这种风格

    #clip {
      -webkit-clip-path: polygon(50% 50%,100% 0,100% 100%);
      clip-path: polygon(50% 50%,100% 100%);
    }

请参见Canisue CSS clip-path property (for HTML) 有关兼容性的详细信息

var circle = document.getElementById('circle')
var upBtn = document.getElementById('upBtn')
var downBtn = document.getElementById('downBtn')

var rotateValue = circle.style.transform;
var rotateSum;

upBtn.onclick = function() {
  rotateSum = rotateValue + "rotate(-90deg)";
  circle.style.transform = rotateSum;
  rotateValue = rotateSum
}

downBtn.onclick = function() {
  rotateSum = rotateValue + "rotate(90deg)";
  circle.style.transform = rotateSum;
  rotateValue = rotateSum
}

* {
  margin: 0;
  padding: 0;
  font-family: sans-serif;
}

.main {
  width: 100%;
  height: 100vh;
  position: relative;
  overflow: hidden;
  background: linear-gradient(to right,#020007,#01060a);
}

nav {
  width: 80%;
  position: sticky;
  margin: 20px auto;
  z-index: 1;
  display: flex;
  align-items: center;
}

.logo {
  flex-basis: 20%;
}

.logo img {
  width: 200px;
  border-radius: 10px;
  position: relative;
  left: -5rem;
}

.nav-links {
  flex: 1;
  text-align: right;
}

.nav-links ul li {
  list-style: none;
  display: inline-block;
  margin: 0px 20px;
}

.nav-links ul li a {
  color: #fff;
  text-decoration: none;
}

.information {
  width: 1000px;
  height: 1000px;
  position: absolute;
  top: 50%;
  left: -10%;
  transform: translateY(-50%);
}

#clip {
  -webkit-clip-path: polygon(50% 50%,100% 100%);
  clip-path: polygon(50% 50%,100% 100%);
}

#circle {
  width: 1000px;
  height: 1000px;
  top: 0;
  left: 0;
  border-radius: 50%;
  transform: rotate(0deg);
  transition: 0.4s;
}

.feature img {
  width: 100px;
  position: relative;
  object-fit: contain;
  border-radius: 10%;
}

.feature {
  display: flex;
  color: #fff;
  position: absolute;
}

.feature div {
  margin-left: 30px;
}

.feature div p {
  margin-top: 8px;
}

.one {
  top: 450px;
  right: 50px;
}

.two {
  top: 150px;
  left: 350px;
  transform: rotate(-90deg);
}

.three {
  bottom: 450px;
  left: 50px;
  transform: rotate(-180deg);
}

.four {
  bottom: 150px;
  right: 350px;
  transform: rotate(-270deg);
}

.char {
  border-radius: 10px;
  position: absolute;
  width: 200px;
  top: 50%;
  left: 35%;
  transform: translateY(-50%);
  z-index: 1;
}

.controls {
  position: absolute;
  right: 10%;
  top: 50%;
  transform: translateY(-50%);
  text-align: center;
}

.controls h3 {
  margin: 15px 0;
  color: #fff;
}

#upBtn {
  border: 3px solid grey;
  width: 20px;
  cursor: pointer;
  border-radius: 10px;
  transform: rotate(180deg);
}

#downBtn {
  border: 3px solid grey;
  width: 20px;
  cursor: pointer;
  border-radius: 10px;
}

#downBtn:hover {
  width: 21px
}

#upBtn:hover {
  width: 21px
}

.overlay {
  width: 0;
  height: 0;
  border-top: 500px solid #ccc;
  border-right: 500px solid black;
  border-bottom: 500px solid #ccc;
  border-left: 500px solid #ccc;
  position: absolute;
  left: 0;
  top: 0;
}

.cover1 {
  position: absolute;
  width: 100px;
  background-color: red;
  height: 100px;
}

.cover2 {
  position: absolute;
}

.cover2 {
  position: ;
}

<base href="https://samuelng87.github.io/ns-pet-switch" />
<div class="main">
  <nav>
    <div class="logo">
      <img src="https://samuelng87.github.io/ns-pet-switch/ns-logo.jpg" alt="logo">
    </div>
    <div class="nav-links">
      <ul>
        <li><a href="#">Home</a></li>
        <li><a href="#">About</a></li>
        <li><a href="#">Game</a></li>
        <li><a href="#">Status</a></li>
      </ul>
    </div>
  </nav>
  <div class="cover1"></div>
  <div class="cover2"></div>
  <div class="cover3"></div>
  <div class="information">
    <div class="overlay"></div>
    <img src="https://samuelng87.github.io/ns-pet-switch/mainchar.png" alt="char" class="char">

    <div id="clip">
      <div id="circle">
        <div class="feature one"><img src="https://samuelng87.github.io/ns-pet-switch/nibi.png" alt="cat">
          <div>
            <h1>Nibi</h1>
            <p>Defence & Attack</p>
          </div>
        </div>

        <div class="feature two"><img src="https://samuelng87.github.io/ns-pet-switch/yobi.png" alt="bird">
          <div>
            <h1>Yobi</h1>
            <p>Full Defence</p>
          </div>
        </div>

        <div class="feature three"><img src="https://samuelng87.github.io/ns-pet-switch/emna.png" alt="monkey">
          <div>
            <h1>Enna</h1>
            <p>Full Attack</p>
          </div>
        </div>
        <div class="feature four"><img src="https://samuelng87.github.io/ns-pet-switch/gobi.png" alt="dog">
          <div>
            <h1>Gobi</h1>
            <p>Full Attack</p>
          </div>
        </div>
      </div>
    </div>
  </div>
  <div class="controls">
    <img src="https://samuelng87.github.io/ns-pet-switch/kunai.png" alt="arrow" id="upBtn">
    <h3>Pets</h3>
    <img src="https://samuelng87.github.io/ns-pet-switch/kunai.png" alt="arrow" id="downBtn">
  </div>
</div>

一种替代方法是使用两个线性渐变作为蒙版

#clip {
  width: 1000px;
  height: 1000px;
  top: 0;
  left: 0;
  -webkit-mask-image: linear-gradient(225deg,#000 50%,transparent 50%),linear-gradient(-45deg,transparent 50%);
  mask-image: linear-gradient(225deg,transparent 50%);
  -webkit-mask-size: 50% 50%,50% 50%;
  mask-size: 50% 50%,50% 50%;
  -webkit-mask-position: 100% 100%,100% 0%;
  mask-position: 100% 100%,100% 0%;
  -webkit-mask-repeat: no-repeat;
  mask-repeat: no-repeat;
}

var circle = document.getElementById('circle')
var upBtn = document.getElementById('upBtn')
var downBtn = document.getElementById('downBtn')

var rotateValue = circle.style.transform;
var rotateSum;

upBtn.onclick = function() {
  rotateSum = rotateValue + "rotate(-90deg)";
  circle.style.transform = rotateSum;
  rotateValue = rotateSum
}

downBtn.onclick = function() {
  rotateSum = rotateValue + "rotate(90deg)";
  circle.style.transform = rotateSum;
  rotateValue = rotateSum
}

* {
  margin: 0;
  padding: 0;
  font-family: sans-serif;
}

.main {
  width: 100%;
  height: 100vh;
  position: relative;
  overflow: hidden;
  background: linear-gradient(to right,#01060a);
}

nav {
  width: 80%;
  position: sticky;
  margin: 20px auto;
  z-index: 1;
  display: flex;
  align-items: center;
}

.logo {
  flex-basis: 20%;
}

.logo img {
  width: 200px;
  border-radius: 10px;
  position: relative;
  left: -5rem;
}

.nav-links {
  flex: 1;
  text-align: right;
}

.nav-links ul li {
  list-style: none;
  display: inline-block;
  margin: 0px 20px;
}

.nav-links ul li a {
  color: #fff;
  text-decoration: none;
}

.information {
  width: 1000px;
  height: 1000px;
  position: absolute;
  top: 50%;
  left: -10%;
  transform: translateY(-50%);
}

#clip {
  width: 1000px;
  height: 1000px;
  top: 0;
  left: 0;
  -webkit-mask-image: linear-gradient(225deg,100% 0%;
  -webkit-mask-repeat: no-repeat;
  mask-repeat: no-repeat;
}

#circle {
  width: 1000px;
  height: 1000px;
  top: 0;
  left: 0;
  border-radius: 50%;
  transform: rotate(0deg);
  transition: 0.4s;
}

.feature img {
  width: 100px;
  position: relative;
  object-fit: contain;
  border-radius: 10%;
}

.feature {
  display: flex;
  color: #fff;
  position: absolute;
}

.feature div {
  margin-left: 30px;
}

.feature div p {
  margin-top: 8px;
}

.one {
  top: 450px;
  right: 50px;
}

.two {
  top: 150px;
  left: 350px;
  transform: rotate(-90deg);
}

.three {
  bottom: 450px;
  left: 50px;
  transform: rotate(-180deg);
}

.four {
  bottom: 150px;
  right: 350px;
  transform: rotate(-270deg);
}

.char {
  border-radius: 10px;
  position: absolute;
  width: 200px;
  top: 50%;
  left: 35%;
  transform: translateY(-50%);
  z-index: 1;
}

.controls {
  position: absolute;
  right: 10%;
  top: 50%;
  transform: translateY(-50%);
  text-align: center;
}

.controls h3 {
  margin: 15px 0;
  color: #fff;
}

#upBtn {
  border: 3px solid grey;
  width: 20px;
  cursor: pointer;
  border-radius: 10px;
  transform: rotate(180deg);
}

#downBtn {
  border: 3px solid grey;
  width: 20px;
  cursor: pointer;
  border-radius: 10px;
}

#downBtn:hover {
  width: 21px
}

#upBtn:hover {
  width: 21px
}

.overlay {
  width: 0;
  height: 0;
  border-top: 500px solid #ccc;
  border-right: 500px solid black;
  border-bottom: 500px solid #ccc;
  border-left: 500px solid #ccc;
  position: absolute;
  left: 0;
  top: 0;
}

.cover1 {
  position: absolute;
  width: 100px;
  background-color: red;
  height: 100px;
}

.cover2 {
  position: absolute;
}

.cover2 {
  position: ;
}

<base href="https://samuelng87.github.io/ns-pet-switch" />
<div class="main">
  <nav>
    <div class="logo">
      <img src="https://samuelng87.github.io/ns-pet-switch/ns-logo.jpg" alt="logo">
    </div>
    <div class="nav-links">
      <ul>
        <li><a href="#">Home</a></li>
        <li><a href="#">About</a></li>
        <li><a href="#">Game</a></li>
        <li><a href="#">Status</a></li>
      </ul>
    </div>
  </nav>
  <div class="cover1"></div>
  <div class="cover2"></div>
  <div class="cover3"></div>
  <div class="information">
    <div class="overlay"></div>
    <img src="https://samuelng87.github.io/ns-pet-switch/mainchar.png" alt="char" class="char">

    <div id="clip">
      <div id="circle">
        <div class="feature one"><img src="https://samuelng87.github.io/ns-pet-switch/nibi.png" alt="cat">
          <div>
            <h1>Nibi</h1>
            <p>Defence & Attack</p>
          </div>
        </div>

        <div class="feature two"><img src="https://samuelng87.github.io/ns-pet-switch/yobi.png" alt="bird">
          <div>
            <h1>Yobi</h1>
            <p>Full Defence</p>
          </div>
        </div>

        <div class="feature three"><img src="https://samuelng87.github.io/ns-pet-switch/emna.png" alt="monkey">
          <div>
            <h1>Enna</h1>
            <p>Full Attack</p>
          </div>
        </div>
        <div class="feature four"><img src="https://samuelng87.github.io/ns-pet-switch/gobi.png" alt="dog">
          <div>
            <h1>Gobi</h1>
            <p>Full Attack</p>
          </div>
        </div>
      </div>
    </div>
  </div>
  <div class="controls">
    <img src="https://samuelng87.github.io/ns-pet-switch/kunai.png" alt="arrow" id="upBtn">
    <h3>Pets</h3>
    <img src="https://samuelng87.github.io/ns-pet-switch/kunai.png" alt="arrow" id="downBtn">
  </div>
</div>