Did not read it all, but looks your problem comes from nonuniform scale, which leads to skewed, non ortho normal child frames if not treated individually.

I don't know how Unity handles this, but most 3D modeling software does not propagate skewed matrices down to the children. Instead they propagat…

Matrix multiplication is considered to be less work than what you do there I think. I don't know much about performance in Javascript, maybe what you are doing is more efficient or less but I know that code like this

const Vector4& row1 = m2.Row(0);
const Vector4& row2 = m2.Row(1);
const Vec…