setupEnvironment( builder ) {

		let envNode = super.setupEnvironment( builder );

		if ( envNode === null && builder.environmentNode ) {

			envNode = builder.environmentNode;

		}

		return envNode ? new EnvironmentNode( envNode ) : null;

	}
Overwritten since this type of material uses {@link EnvironmentNode}
to implement the PBR (PMREM based) environment mapping. Besides, the
method honors `Scene.environment`.

@param {NodeBuilder} builder - The current node builder.
@return {?EnvironmentNode<vec3>} The environment node.