Apply three.js subdivision modifier without changing outer geometry?

Based on the suggestions in the comments by TheJim01, I was able to dig through the original source and modify the vertex weight, edge weight, and beta values to retain the original shape. My modifications should remove any averaging, and put all the weight toward the source shape.

There were three sections that had to be modified, so I went ahead and made it an option that can be passed into the constructor called retainShape, which defaults to false.

I made a gist with the modified code for SubdivisionGeometry.js.

View the modified SubdivisionGeometry.js Gist

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Below is an example of a cube being subdivided with the option turned off, and turned on.

Left: new THREE.SubdivisionModifier(2, false);

Right: new THREE.SubdivisionModifier(2, true);

If anyone runs into any issues with this or has any questions, let me know!