fromEquirectangular( equirectangular, renderTarget = null ) {

		if ( this._hasInitialized === false ) {

			console.warn( 'THREE.PMREMGenerator: .fromEquirectangular() called before the backend is initialized. Try using .fromEquirectangularAsync() instead.' );

			this._setSizeFromTexture( equirectangular );

			const cubeUVRenderTarget = renderTarget || this._allocateTarget();

			this.fromEquirectangularAsync( equirectangular, cubeUVRenderTarget );

			return cubeUVRenderTarget;

		}

		return this._fromTexture( equirectangular, renderTarget );

	}
Generates a PMREM from an equirectangular texture, which can be either LDR
or HDR. The ideal input image size is 1k (1024 x 512),
as this matches best with the 256 x 256 cubemap output.

@param {Texture} equirectangular - The equirectangular texture to be converted.
@param {?RenderTarget} [renderTarget=null] - The render target to use.
@return {RenderTarget} The resulting PMREM.
@see {@link PMREMGenerator#fromEquirectangularAsync}