updateBefore( frame ) {

		const { shadow } = this;

		let needsUpdate = shadow.needsUpdate || shadow.autoUpdate;

		if ( needsUpdate ) {

			if ( this._cameraFrameId[ frame.camera ] === frame.frameId ) {

				needsUpdate = false;

			}

			this._cameraFrameId[ frame.camera ] = frame.frameId;

		}

		if ( needsUpdate ) {

			this.updateShadow( frame );

			if ( this.shadowMap.depthTexture.version === this._depthVersionCached ) {

				shadow.needsUpdate = false;

			}

		}

	}
The implementation performs the update of the shadow map if necessary.

@param {NodeFrame} frame - A reference to the current node frame.