setupEnvironment( /*builder*/ ) {

		let node = null;

		if ( this.envNode ) {

			node = this.envNode;

		} else if ( this.envMap ) {

			node = this.envMap.isCubeTexture ? materialReference( 'envMap', 'cubeTexture' ) : materialReference( 'envMap', 'texture' );

		}

		return node;

	}
Setups the environment node from the material.

@param {NodeBuilder} builder - The current node builder.
@return {Node<vec4>} The environment node.