constructor( renderer ) {

		this._renderer = renderer;
		this._pingPongRenderTarget = null;

		this._lodMax = 0;
		this._cubeSize = 0;
		this._lodPlanes = [];
		this._sizeLods = [];
		this._sigmas = [];
		this._lodMeshes = [];

		this._blurMaterial = null;
		this._cubemapMaterial = null;
		this._equirectMaterial = null;
		this._backgroundBox = null;

	}
Constructs a new PMREM generator.

@param {Renderer} renderer - The renderer.