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updating SVG animateMotion path using JavaScript

Time:08-29

I try changing an SVG motion path according to a html select value using JS. The path updates as expected, but the element, which uses the path as a motion path continues to move along the original path. What am I missing?

function changepath(selectObject) {
  let value = selectObject.value;
     let path = document.getElementById("planePath");
     let plane = document.getElementById("animPath");
    
     let rotation = "rotate("   value   ")";
     path.setAttribute("transform", rotation);
     plane.setAttribute("transform", rotation);
}
body {
 background: #eee;
}

.planePath {
    opacity: 0.8;
 stroke: darkslategrey;
 stroke-width: 2px;
 fill: none;
}

.plane {
    transform: scale(0.15);
}

select {
    margin-left: 2em;;
}
<svg viewBox="0 0 2000 200">
<!--    <path  id="planePath" d="M 0 0 C 200 250 250 50 550 150 C 850 250 700 180 1000 200 " /> -->
        <path  id="planePath" d="M 50 100 c 14 -3 736 -115 1900 0" />
    <g id="plane" >
    <rect x="0" y="0" width="100" height="100"/>
 </g>
 <animateMotion xlink:href="#plane" dur="6s" repeatCount="indefinite" rotate="auto">
  <mpath id="animPath" xlink:href="#planePath" />
    </animateMotion>
</svg>

<select name="route" id="route" onchange="changepath(this)">
     <option value="0">0°</option>
  <option value="1">1°</option>
  <option value="2">2°</option>
  <option value="3">3°</option>
  <option value="4">4°</option>
</select>

CodePudding user response:

As Danny mentioned in his answer the mpath is using the untransformed path. If you need it to be transformed you can wrap both the path and the animated rect in a group and transform the group.

<svg viewBox="0 0 2000 200">
 <g transform="rotate(5)">
  <path id="path" fill="none" stroke="red" stroke-width="5" 
        d="M 50 100 c 14 -3 736 -115 1900 0" />
  <rect id="block" x="0" y="0" width="20" height="20"/>
  <animateMotion href="#block" dur="2s" repeatCount="indefinite" 
                 rotate="auto" restart="always">
    <mpath href="#path" />
  </animateMotion>
 </g>
</svg>

CodePudding user response:

Looks like animateMotion mpath can't handle the transform

<svg viewBox="0 0 2000 200">
  <path id="NO_rotate" fill="none" stroke="green" stroke-width="5" 
        d="M 50 100 c 14 -3 736 -115 1900 0"/>
  <path id="path" fill="none" stroke="red" stroke-width="5" 
        d="M 50 100 c 14 -3 736 -115 1900 0" 
        transform="rotate(5)"/>
  <rect id="block" x="0" y="0" width="20" height="20"/>
  <animateMotion href="#block" dur="2s" repeatCount="indefinite" 
                 rotate="auto" restart="always">
    <mpath href="#path" />
  </animateMotion>
</svg>

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