What is the Expected Input for applyToBufferAttribute() in the Three.js OffsetContour Function?

I'm trying to offset a simple square using the OffsetContour function (more Resources) as shown in the example below:

JAVASCRIPTCopied
function OffsetContour(offset, contour) {
    let result = [];
    offset = new THREE.BufferAttribute(new Float32Array([offset, 0, 0]), 3);
    for (let i = 0; i < contour.length; i++) {
        let v1 = new THREE.Vector2().subVectors(contour[i - 1 < 0 ? contour.length - 1 : i - 1], contour[i])…
    }
}```

I set up a test environment in codesandbox:

<https://codesandbox.io/p/sandbox/63h94y?file=%2Fsrc%2Findex.mjs%3A180%2C1>

However, I encounter the following error:

> TypeError
> shiftMatrix.applyToBufferAttribute is not a function

This leads me to ask: What is the expected input for this function? Is it expecting THREE.Vector2 points? I couldn’t find any methods named applyToBufferAttribute() in the Three.js documentation.

Thanks for your help!