SVG 路径叠加并动画出另一条路径

Question

我有一个灰色虚线的 SVG。我想要做的是将其覆盖在绿色 SVG 虚线之上，并动画化灰色以显示绿色。有点像从右向左移动的仪表。

我看到了这个如何制作虚线的例子：

并且能够做到，但我的线已经是虚线了。

我最终这样做了：

<svg version="1.1" id="Layer_1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px"
         viewBox="0 0 666.9 123.8" enable-background="new 0 0 666.9 123.8" xml:space="preserve">
    <path  opacity="0.4" stroke-width="3" fill="none" stroke="#66CD00" stroke-linecap="round" stroke-miterlimit="5" stroke-dasharray="1,6" d="
        M656.2,118.5c0,0-320.4-251-645.9-0.7" />
        <path id="top"  opacity="0.4" fill="none" stroke="#AEAEAE" stroke-linecap="round" stroke-miterlimit="5" stroke-dasharray="1,6" d="
    M656.2,118.5c0,0-320.4-251-645.9-0.7"/>

</svg>

var path = document.querySelector('#top');
var length = path.getTotalLength();
// Clear any previous transition
path.style.transition = path.style.WebkitTransition =
  'none';
// Set up the starting positions
path.style.strokeDasharray = 1  + ' ' + 6;
path.style.strokeDashoffset = length;

// Trigger a layout so styles are calculated & the browser
// picks up the starting position before animating
path.getBoundingClientRect();
// Define our transition
path.style.transition = path.style.WebkitTransition =
  'stroke-dashoffset 20s linear';
// Go!
path.style.strokeDashoffset = '0';

https://jsfiddle.net/ps5yLyab/

如何叠加两条虚线并动画化灰色？

Answer 1

您可以使用剪辑路径来完成。

首先我们向 SVG 添加一个 clipPath。

<defs>
    <clipPath id="myclip">
        <rect id="cliprect" x="100%" y="0%" width="100%" height="100%"/>
    </clipPath>
</defs>

此剪辑路径的大小与 SVG 相同（宽度和高度 100%），并从 SVG (100%) 最右侧的 x 位置开始。所以一开始它并没有透露任何东西。

然后每 10 毫秒我们将其 x 坐标减少 1%（即 100% -> 99% -> 98% 等）。直到它达到零。

var cliprect = document.getElementById("cliprect");
var offsetX = 100;
var speed = 10;

function clipAdjust()
{
    cliprect.setAttribute("x", offsetX+"%");
    offsetX -= 1;
    if (offsetX >= 0) {
        window.setTimeout(clipAdjust, speed);
    }
}

window.setTimeout(clipAdjust, speed);

下面的工作演示：

var path = document.querySelector('#top');
  var length = path.getTotalLength();
  // Clear any previous transition
  path.style.transition = path.style.WebkitTransition =
    'none';
  // Set up the starting positions
  path.style.strokeDasharray = 1  + ' ' + 6;
  path.style.strokeDashoffset = length;

  // Trigger a layout so styles are calculated & the browser
  // picks up the starting position before animating
  path.getBoundingClientRect();
  // Define our transition
  path.style.transition = path.style.WebkitTransition =
    'stroke-dashoffset 20s linear';
  // Go!
  path.style.strokeDashoffset = '0';

var cliprect = document.getElementById("cliprect");
var offsetX = 100;
var speed = 10;

function clipAdjust()
{
    cliprect.setAttribute("x", offsetX+"%");
    offsetX -= 1;
    if (offsetX >= 0) {
        window.setTimeout(clipAdjust, speed);
    }
}

window.setTimeout(clipAdjust, speed);

<svg version="1.1" id="Layer_1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px"
   viewBox="0 0 666.9 123.8" enable-background="new 0 0 666.9 123.8" xml:space="preserve">

    <defs>
        <clipPath id="myclip">
            <rect id="cliprect" x="100%" y="0%" width="100%" height="100%"/>
        </clipPath>
    </defs>

    <path opacity="0.4" fill="none" stroke="#AEAEAE" stroke-linecap="round"
          stroke-miterlimit="5" stroke-dasharray="1,6" stroke-width="2"
          d="M656.2,118.5c0,0-320.4-251-645.9-0.7"/>

    <g clip-path="url(#myclip)">
        <path stroke-width="3" fill="none" stroke="white"
              stroke-linecap="round" stroke-miterlimit="5"
              d="M656.2,118.5c0,0-320.4-251-645.9-0.7" />
        <path id="top"  opacity="0.4" stroke-width="3" fill="none" stroke="#66CD00"
              stroke-linecap="round" stroke-miterlimit="5" stroke-dasharray="6,6"
              d="M656.2,118.5c0,0-320.4-251-645.9-0.7" />
    </g>
  
</svg>

SVG 路径叠加并动画出另一条路径

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