constructor( r, g, b, a = 1 ) {

		super( r, g, b );

		this.a = a;

	}
Constructs a new four-component color.
You can also pass a single THREE.Color, hex or
string argument to this constructor.

@param {number|string} [r=1] - The red value.
@param {number} [g=1] - The green value.
@param {number} [b=1] - The blue value.
@param {number} [a=1] - The alpha value.