css3 动画之满意度表情变化的复杂动画

实现效果：

拉动滑动条，表情由愤怒到满意，并且颜色也由红色逐渐变更成绿色
如下图：

实现思路：

1. 利用clip-path实现多边形蒙版对眼睛部分进行绘制

  .eye {
        position: absolute;
        top: 45px;
        width: 40px;
        height: 40px;
        background-color: #fff;
        border-radius: 50%;
        clip-path: polygon(0 70%, 100% 0, 100% 100%, 0 100%);
      }

2. 利用 box-shadow 的 insert 属性可以绘制内部阴影的特性，对圆形绘制内阴影形成嘴部表情

      .mouse {
        height: 60px;
        width: 70px;
        position: absolute;
        left: calc(50% - 35px);
        top: 86px;
        /* border-radius: 30px; */
        border-radius: 50%;
        box-shadow: inset 0 6px 0 #fff;
        clip-path: inset(0% 0% 0% 0%);
        transform: translateY(30px);
        animation: mouse 1s linear var(--delay) 1 forwards paused;
      }

3. 对滑动条样式修改，动态计算滑过的部分，并设置渐变条

      #rangeInput {
        -webkit-appearance: none;
        margin-top: 40px;
        height: 24px;
        width: 180px;
        border-radius: 12px;
        box-shadow: 0px 0px 8px 0px rgb(125, 125, 125);
        animation: face 1s linear var(--delay) 1 forwards paused;
        background-size: var(--slide) 100%;
        background-repeat: no-repeat;
      }

完整代码：

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>表情变化动画</title>
  </head>
  <body>
    <style>
      body {
        margin: 0;
        padding: 0;
        --delay: 0;
        --slide: 0%;
      }
      #rangeInput {
        -webkit-appearance: none;
        margin-top: 40px;
        height: 24px;
        width: 180px;
        border-radius: 12px;
        box-shadow: 0px 0px 8px 0px rgb(125, 125, 125);
        animation: face 1s linear var(--delay) 1 forwards paused;
        background-size: var(--slide) 100%;
        background-repeat: no-repeat;
      }
      /*拖动块的样式*/
      input[type="range"]::-webkit-slider-thumb {
        -webkit-appearance: none;
        height: 24px;
        width: 24px;
        background: #fff;
        border-radius: 50%;
        border: solid 1px #ddd;
      }
      .container {
        margin-top: 200px;
        display: flex;
        flex-direction: column;
        align-items: center;
        justify-content: center;
      }
      .face {
        position: relative;
        background-color: red;
        width: 180px;
        height: 180px;
        border-radius: 50%;
        animation: face 1s linear var(--delay) 1 forwards paused;
      }

      .eye {
        position: absolute;
        top: 45px;
        width: 40px;
        height: 40px;
        background-color: #fff;
        border-radius: 50%;
      }
      .left {
        left: 36px;
        animation: leftEye 1s linear var(--delay) 1 forwards paused;
      }
      .right {
        right: 36px;
        animation: rightEye 1s linear var(--delay) 1 forwards paused;
      }
      .mouse {
        height: 60px;
        width: 70px;
        position: absolute;
        left: calc(50% - 35px);
        top: 86px;
        /* border-radius: 30px; */
        border-radius: 50%;
        box-shadow: inset 0 6px 0 #fff;
        clip-path: inset(0% 0% 0% 0%);
        transform: translateY(30px);
        animation: mouse 1s linear var(--delay) 1 forwards paused;
      }
      @keyframes face {
        0% {
          background-image: linear-gradient(to left top, #ff0000, #f36400);
        }
        20% {
          background-image: linear-gradient(to left top, #f36400, #dd9200);
        }
        40% {
          background-image: linear-gradient(to left top, #dd9200, #c1b700);
        }
        60% {
          background-image: linear-gradient(to left top, #c1b700, #d5a700);
        }
        80% {
          background-image: linear-gradient(to left top, #d5a700, #9fd600);
        }
        100% {
          background-image: linear-gradient(
            to left top,
            #9fd600,
            #8fe000,
            #7aea00,
            #5af50a,
            #00ff21
          );
        }
      }
      @keyframes mouse {
        50% {
          height: 6px;
          box-shadow: inset 0 6px 0 #fff;
          clip-path: inset(0% 0% 0% 0%);
          transform: translateY(40px);
        }
        50.1% {
          height: 6px;
          box-shadow: inset 0 -6px 0 #fff;
          clip-path: inset(50% 0% 0% 0%);
          transform: translateY(40px);
        }
        100% {
          height: 60px;
          box-shadow: inset 0 -40px 0 #fff;
          clip-path: inset(50% 0% 0% 0%);
          transform: translateY(0);
        }
      }
      @keyframes leftEye {
        from {
          clip-path: polygon(0 70%, 100% 0, 100% 100%, 0 100%);
        }
        to {
          clip-path: polygon(0 0, 100% 0, 100% 100%, 0 100%);
        }
      }
      @keyframes rightEye {
        from {
          clip-path: polygon(0 0, 100% 70%, 100% 100%, 0 100%);
        }
        to {
          clip-path: polygon(0 0, 100% 0, 100% 100%, 0 100%);
        }
      }
    </style>
    <div class="container">
      <div class="face">
        <span class="left eye"></span>
        <span class="right eye"></span>
        <span class="mouse"></span>
      </div>
      <input type="range" id="rangeInput" min="0" max="1" step="0.01" />
    </div>
    <script>
      const input = document.querySelector("#rangeInput");
      const move = () => {
        document.body.style.setProperty("--delay", `-${input.value}s`);
        document.body.style.setProperty(
          "--slide",
          `${input.value * 156 + 12}px`
        );
      };
      move();
      input.oninput = move;
    </script>
  </body>
</html>

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