SVG无限动画无法正常工作

Question

我已经创建了 SVG 无限动画，但它运行不顺畅，它卡在中间然后流走。 SVG 中 Illustrator 中的已解决节点，但之后我遇到了同样的问题。有人可以查看代码并帮助我吗？

.svg-main {
    width: 700px;
    margin: 30px auto;
    position: relative;
}
svg#svga {
    position: absolute;
    top: 0;
    left: auto;
    bottom: auto;
    right: auto;
}

.sd1{fill:none;stroke:#000000; stroke-width:6;stroke-linecap:round;stroke-linejoin:round;stroke-miterlimit:10;}
.circ{fill:#000000; }
.st0{fill:#cccccc;}
.st1{fill:#cccccc;}
.st2{fill:none;stroke:#cccccc;stroke-width:6;stroke-miterlimit:10;}

<div class="svg-main">
<svg version="1.1" id="svga" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px"
	 width="300px" height="200px" viewBox="0 0 685 310" style="enable-background:new 0 0 671.1 304.4;" xml:space="preserve"
	>
<g class="svg-col">
	<path class="sd1" id="loop-normal" d="M343.6,156.5c11,15.9,104.6,147.2,181.9,147.6c0.1,0,0.8,0,1,0c82.1-0.3,148.6-67,148.6-149.2
	c0-82.4-66.8-149.2-149.2-149.2c-77.2,0-170.8,131-182.2,147.5c-0.8,1.1-1.6,2.3-2.1,3.1c-10.6,15.3-104.8,147.8-182.4,147.8
	C76.7,304.2,9.9,237.4,9.9,155S76.7,5.8,159.1,5.8c77.2,0,170.7,130.9,182.2,147.5C342.1,154.4,342.9,155.6,343.6,156.5z"/>
		<animate attributeName="stroke-dasharray" attributeType="XML"
		    	from="1900, 1700"  to="200 1700"
		    	begin="0s" dur="3s"
		    	repeatCount="indefinite"/>
		<animate attributeName="stroke-dashoffset" attributeType="XML"
	    	from="-1700"  to="-3600"
	    	begin="0s" dur="3s"
	    	repeatCount="indefinite"/>  
	</path>

	<circle id="plug" class="circ" cx="0" cy="0" r="7"/> 
	<animateMotion
		xlink:href="#plug"
	  	dur="3s"
		rotate="auto"
		repeatCount="indefinite"
		calcMode="linear"
		keyTimes="0;1"    
		keySplines="0.42, 0, 0.58, 1">
		<mpath xlink:href="#loop-normal"/>
	</animateMotion> 
</g>	
</svg>
 
<!-- Generator: Adobe Illustrator 22.1.0, SVG Export Plug-In . SVG Version: 6.00 Build 0)  -->
<svg version="1.1" id="svg-bg" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px"
	 width="300px" height="200px" viewBox="0 0 685 310" style="enable-background:new 0 0 685 310;" xml:space="preserve"> 
<path class="st2" d="M159.1,5.8C76.7,5.8,9.9,72.6,9.9,155s66.8,149.2,149.2,149.2S342.5,155,342.5,155S241.5,5.8,159.1,5.8z
	 M525.9,5.8C443.5,5.8,342.5,155,342.5,155s101,149.2,183.4,149.2S675.1,237.4,675.1,155S608.3,5.8,525.9,5.8z"/>
</svg>
</div>

Answer 1

使用stroke-dashoffset 动画获得流畅运动的第一个先决条件是以适当的精度知道路径的长度：

document.querySelector('#loop-normal').getTotalLength() // approx. 1910

1. 省略stroke-dasharray 的动画。而是将路径的总长度静态划分为一个破折号和一个间隙：stroke-dasharray="200 1710"。 （只要总和等于 1910，任何其他比例都可以。）
2. 您的<animateMotion> 缺少keyPoints 属性。将其设置为“0;1”
3. 只要不设置calcMode="spline"，定义keySplines 就无效。别管它。

剩下的有点简化：只定义一次路径，并将背景和动画使用定位在同一个 SVG 中；在stroke-dashoffset 动画中命名正确的路径长度以确保平滑移动；删除未使用的 CSS。

.svg-main {
    width: 700px;
    margin: 30px auto;
    position: relative;
}
svg#svga {
    position: absolute;
    top: 0;
    left: auto;
    bottom: auto;
    right: auto;
}

.st2{fill:none;stroke:#cccccc;stroke-width:6;}
.sd1{fill:none;stroke:#000000; stroke-width:6;stroke-linecap:round;}
.circ{fill:#000000; }

<div class="svg-main">
<svg id="svga" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"
	 width="300px" height="200px" viewBox="0 0 685 310">
  <g class="st2">
	<path id="loop-normal" d="M343.6,156.5c11,15.9,104.6,147.2,181.9,147.6c0.1,0,0.8,0,1,0c82.1-0.3,148.6-67,148.6-149.2
	c0-82.4-66.8-149.2-149.2-149.2c-77.2,0-170.8,131-182.2,147.5c-0.8,1.1-1.6,2.3-2.1,3.1c-10.6,15.3-104.8,147.8-182.4,147.8
	C76.7,304.2,9.9,237.4,9.9,155S76.7,5.8,159.1,5.8c77.2,0,170.7,130.9,182.2,147.5C342.1,154.4,342.9,155.6,343.6,156.5z"/>
  </g>
	<use class="sd1" stroke-dasharray="200 1710" xlink:href="#loop-normal">
		<animate attributeName="stroke-dashoffset"
	    	from="200"  to="-1710"
	    	begin="0s" dur="3s"
	    	repeatCount="indefinite"/>  
	</use>

	<circle id="plug" class="circ" cx="0" cy="0" r="7"/> 
	<animateMotion
		xlink:href="#plug"
	  	dur="3s"
		rotate="auto"
		repeatCount="indefinite"
		calcMode="linear"
		keyTimes="0;1"    
		keyPoints="0;1">
		<mpath xlink:href="#loop-normal"/>
	</animateMotion> 
</svg>
</div>