constructor() {
			this.coefficients = [];

			for (let i = 0; i < 9; i++) {
				this.coefficients.push(new Vector3());
			}
		}
Primary reference:
	 https://graphics.stanford.edu/papers/envmap/envmap.pdf

Secondary reference:
	 https://www.ppsloan.org/publications/StupidSH36.pdf