sousa-gecko/testing/web-platform/tests/css/css-transforms/3d-point-mapping-3.html

<!DOCTYPE html>
<title>Point mapping through 3D transform hierarchies</title>
<link rel="help" href="https://drafts.csswg.org/cssom-view/#dom-document-elementfrompoint">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>

<style type="text/css" media="screen">
  #scene {
    position: absolute;
    border: 1px solid black;
    height: 400px;
    width: 400px;
    perspective: 600px;
    transform-style: preserve-3d;
  }

  #container {
    position: absolute;
    height: 300px;
    width: 300px;
    margin: 50px;
    border: 1px solid blue;
    transform-style: preserve-3d;
  }

  #card {
    position: absolute;
    top: 50px;
    left: 50px;
    height: 200px;
    width: 200px;
    background-color: #81AA8A;
    transform-origin: right top;
    transform: rotateY(45deg);
  }

  #card:hover {
    background-color: orange;
  }
</style>

<body>
  <div id="scene">
    <div id="container">
      <div id="card"></div>
    </div>
  </div>
</body>

<script>
  class Point {
    constructor(x, y) {
      this.x = x;
      this.y = y;
    }
  };
  const tests = [{
      expectedElemId: 'card',
      // Points inside the 3D-transformed element
      insidePoints: [
        new Point(160, 85),   // Top-left
        new Point(306, 113),  // Top-right
        new Point(160, 335),  // Bottom-left
        new Point(307, 307),  // Bottom-right
      ],
      // Points outside the 3D-transformed element
      outsidePoints: [
        new Point(115, 115),  // Inside top-left when untransformed
        new Point(115, 300),  // Inside bottom-left when untransformed
      ]
    }
  ];

  tests.forEach(testcase => {
    test(t => {
      const expectedElem = document.getElementById(testcase.expectedElemId);
      // Test points that should hit the element
      for (const point of testcase.insidePoints) {
        const hitElem = document.elementFromPoint(point.x, point.y);
        assert_equals(hitElem, expectedElem,
          `point (${point.x}, ${point.y}) should be inside element ${testcase.expectedElemId}`);
      }
      // Test points that should NOT hit the element
      for (const point of testcase.outsidePoints) {
        const hitElem = document.elementFromPoint(point.x, point.y);
        assert_not_equals(hitElem, expectedElem,
          `point (${point.x}, ${point.y}) should be outside element ${testcase.expectedElemId}`);
      }
    }, `${document.title}, hittesting ${testcase.expectedElemId})`);
  });
</script>

</html>