Using clipPathUnits="objectBoundingBox" makes clip path disappear

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Problem:

I've created an SVG Clip Path which needs to be responsive, but when I try to use clipPathUnits="objectBoundingBox" in the clip path tag, it makes the target object disappear.

I made example snippets with and without. The first one shows as expected, but the second is completely hidden.

I've tested it with various simple shapes and paths which work fine, but I can't get clipPathUnits="objectBoundingBox" working with anything more complicated, not sure what I'm missing.

Snippet:

body {
  background: #333;
}

#hero {
  background: url(https://source.unsplash.com/random);
  height: 120vh;
  background-color: #ff0000;
  width: 100vw;
  background-size: cover;
  clip-path: url(#wav);
}

#hero2 {
  background: url(https://source.unsplash.com/random);
  height: 120vh;
  background-color: #ff0000;
  width: 100vw;
  background-size: cover;
  clip-path: url(#wav2);
}
<div id="hero"></div>
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100">
      <clipPath id="wav" >
        <path d="M815.8,19.7c-18.9,0-18.7,15.3-37.9,15.3-17.6,0-19.6-13-38-13-15,0-14.9,11.1-38,11.1C672.5,33.1,676,4.6,640,4.6s-40.1,39.9-79.8,39.9c-33,0-38.7-18-63-18s-32.8,15.9-49.9,15.9c-13.1,0-19.7-4-26.3-9.7h0c-6.5-5.6-13.2-13-26.3-13C375.8,19.7,376,35,356.9,35c-17.6,0-19.7-13-38-13-15.1,0-14.9,11.1-38,11.1C251.5,33.1,255,4.6,219,4.6s-40.1,39.9-79.8,39.9c-33,0-38.7-18-63-18S43.3,42.4,26.3,42.4c-13.1,0-19.7-4-26.3-9.7V562.6c6.5,5.6,13.2,12.9,26.2,12.9,18.9,0,18.7-15.2,37.9-15.2,17.6,0,19.6,12.9,38,12.9,15,0,14.9-11,38-11,29.4,0,25.9,28.5,61.9,28.5s40.1-39.9,79.8-39.9c33,0,38.7,18,63,18s32.8-15.9,49.9-15.9c13.1,0,19.7,4,26.3,9.6h0c6.5,5.7,13.2,13,26.3,13,18.9,0,18.7-15.2,37.8-15.2,17.6,0,19.7,12.9,38,12.9,15.1,0,14.9-11,38-11,29.4,0,25.9,28.5,61.9,28.5s40.1-39.9,79.8-39.9c33,0,38.7,18,63,18s32.9-15.9,49.9-15.9c13.1,0,19.7,4,26.3,9.6V32.7C835.5,27.1,828.8,19.7,815.8,19.7Z" />
      </clipPath>       
  </svg>


<div id="hero2"></div>
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100">
      <clipPath id="wav2" clipPathUnits="objectBoundingBox">
        <path d="M815.8,19.7c-18.9,0-18.7,15.3-37.9,15.3-17.6,0-19.6-13-38-13-15,0-14.9,11.1-38,11.1C672.5,33.1,676,4.6,640,4.6s-40.1,39.9-79.8,39.9c-33,0-38.7-18-63-18s-32.8,15.9-49.9,15.9c-13.1,0-19.7-4-26.3-9.7h0c-6.5-5.6-13.2-13-26.3-13C375.8,19.7,376,35,356.9,35c-17.6,0-19.7-13-38-13-15.1,0-14.9,11.1-38,11.1C251.5,33.1,255,4.6,219,4.6s-40.1,39.9-79.8,39.9c-33,0-38.7-18-63-18S43.3,42.4,26.3,42.4c-13.1,0-19.7-4-26.3-9.7V562.6c6.5,5.6,13.2,12.9,26.2,12.9,18.9,0,18.7-15.2,37.9-15.2,17.6,0,19.6,12.9,38,12.9,15,0,14.9-11,38-11,29.4,0,25.9,28.5,61.9,28.5s40.1-39.9,79.8-39.9c33,0,38.7,18,63,18s32.8-15.9,49.9-15.9c13.1,0,19.7,4,26.3,9.6h0c6.5,5.7,13.2,13,26.3,13,18.9,0,18.7-15.2,37.8-15.2,17.6,0,19.7,12.9,38,12.9,15.1,0,14.9-11,38-11,29.4,0,25.9,28.5,61.9,28.5s40.1-39.9,79.8-39.9c33,0,38.7,18,63,18s32.9-15.9,49.9-15.9c13.1,0,19.7,4,26.3,9.6V32.7C835.5,27.1,828.8,19.7,815.8,19.7Z" />
      </clipPath>       
  </svg>

Resources:

https://www.w3.org/TR/SVG11/masking.html#ClipPathElementClipPathUnitsAttribute

https://developer.mozilla.org/en-US/docs/Web/SVG/Attribute/clipPathUnits

https://www.sarasoueidan.com/blog/css-svg-clipping/

svg css
1 Answers

When using clipPathUnits="objectBoundingBox" the width and height of the object bounding box of the clipping path are considered to have a length of 1 unit value.

In order to achieve this you either need to rewrite the d attribute of the path or you can scale the path. In this case I use transform="scale(0.00118,0.0017)"

 <clipPath id="wav" clipPathUnits="objectBoundingBox">
            <path transform="scale(0.00118,0.0017)" id="thePath" d="M815.8,19.7c-18.9,0-18.7,15.3-37.9,15.3-17.....

In order to know what value to use

  1. I get the bounding box of the path:

    let bb=thePath.getBBox();

  2. I use the bb.width and bb.height to get the scale:

    let sx = 1/bb.width; let sy = 1/bb.height

  3. I scale the path:

    thePath.setAttribute("transform", scale(${sx},${sy}))

body {
  background: #333;
}

#hero {
  background: url(https://source.unsplash.com/random);
  height: 120vh;
  background-color: #ff0000;
  width: 100vw;
  background-size: cover;
  clip-path: url(#wav);
}

#hero2 {
  background: url(https://source.unsplash.com/random);
  height: 120vh;
  background-color: #ff0000;
  width: 100vw;
  background-size: cover;
  clip-path: url(#wav2);
}
<div id="hero"></div>
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100">
      <clipPath id="wav" clipPathUnits="objectBoundingBox">
        <path transform="scale(0.00118,0.0017)"  id="thePath" d="M815.8,19.7c-18.9,0-18.7,15.3-37.9,15.3-17.6,0-19.6-13-38-13-15,0-14.9,11.1-38,11.1C672.5,33.1,676,4.6,640,4.6s-40.1,39.9-79.8,39.9c-33,0-38.7-18-63-18s-32.8,15.9-49.9,15.9c-13.1,0-19.7-4-26.3-9.7h0c-6.5-5.6-13.2-13-26.3-13C375.8,19.7,376,35,356.9,35c-17.6,0-19.7-13-38-13-15.1,0-14.9,11.1-38,11.1C251.5,33.1,255,4.6,219,4.6s-40.1,39.9-79.8,39.9c-33,0-38.7-18-63-18S43.3,42.4,26.3,42.4c-13.1,0-19.7-4-26.3-9.7V562.6c6.5,5.6,13.2,12.9,26.2,12.9,18.9,0,18.7-15.2,37.9-15.2,17.6,0,19.6,12.9,38,12.9,15,0,14.9-11,38-11,29.4,0,25.9,28.5,61.9,28.5s40.1-39.9,79.8-39.9c33,0,38.7,18,63,18s32.8-15.9,49.9-15.9c13.1,0,19.7,4,26.3,9.6h0c6.5,5.7,13.2,13,26.3,13,18.9,0,18.7-15.2,37.8-15.2,17.6,0,19.7,12.9,38,12.9,15.1,0,14.9-11,38-11,29.4,0,25.9,28.5,61.9,28.5s40.1-39.9,79.8-39.9c33,0,38.7,18,63,18s32.9-15.9,49.9-15.9c13.1,0,19.7,4,26.3,9.6V32.7C835.5,27.1,828.8,19.7,815.8,19.7Z" />
      </clipPath>       
  </svg>


<div id="hero2"></div>
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100">
      <clipPath id="wav2" clipPathUnits="objectBoundingBox">
        <path d="M815.8,19.7c-18.9,0-18.7,15.3-37.9,15.3-17.6,0-19.6-13-38-13-15,0-14.9,11.1-38,11.1C672.5,33.1,676,4.6,640,4.6s-40.1,39.9-79.8,39.9c-33,0-38.7-18-63-18s-32.8,15.9-49.9,15.9c-13.1,0-19.7-4-26.3-9.7h0c-6.5-5.6-13.2-13-26.3-13C375.8,19.7,376,35,356.9,35c-17.6,0-19.7-13-38-13-15.1,0-14.9,11.1-38,11.1C251.5,33.1,255,4.6,219,4.6s-40.1,39.9-79.8,39.9c-33,0-38.7-18-63-18S43.3,42.4,26.3,42.4c-13.1,0-19.7-4-26.3-9.7V562.6c6.5,5.6,13.2,12.9,26.2,12.9,18.9,0,18.7-15.2,37.9-15.2,17.6,0,19.6,12.9,38,12.9,15,0,14.9-11,38-11,29.4,0,25.9,28.5,61.9,28.5s40.1-39.9,79.8-39.9c33,0,38.7,18,63,18s32.8-15.9,49.9-15.9c13.1,0,19.7,4,26.3,9.6h0c6.5,5.7,13.2,13,26.3,13,18.9,0,18.7-15.2,37.8-15.2,17.6,0,19.7,12.9,38,12.9,15.1,0,14.9-11,38-11,29.4,0,25.9,28.5,61.9,28.5s40.1-39.9,79.8-39.9c33,0,38.7,18,63,18s32.9-15.9,49.9-15.9c13.1,0,19.7,4,26.3,9.6V32.7C835.5,27.1,828.8,19.7,815.8,19.7Z" />
      </clipPath>       
  </svg>

This is from Sara Soueidan's article:

when you use the objectBoundingBox value, the coordinates specified for the contents of the <clipPath> must be in the range [0, 1]

And this is from MDN:

objectBoundingBox This value indicates that all coordinates inside the element are relative to the bounding box of the element the clipping path is applied to. It means that the origin of the coordinate system is the top left corner of the object bounding box and the width and height of the object bounding box are considered to have a length of 1 unit value.

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