<!-- AVATAR-FORGE · part 106 -->
backgroundMaterial.color.copy( _clearColor );
			useSolidColor = true;

		}

		for ( let i = 0; i < 6; i ++ ) {

			const col = i % 3;

			if ( col === 0 ) {

				cubeCamera.up.set( 0, upSign[ i ], 0 );
				cubeCamera.lookAt( forwardSign[ i ], 0, 0 );

			} else if ( col === 1 ) {

				cubeCamera.up.set( 0, 0, upSign[ i ] );
				cubeCamera.lookAt( 0, forwardSign[ i ], 0 );

			} else {

				cubeCamera.up.set( 0, upSign[ i ], 0 );
				cubeCamera.lookAt( 0, 0, forwardSign[ i ] );

			}

			const size = this._cubeSize;

			_setViewport( cubeUVRenderTarget, col * size, i > 2 ? size : 0, size, size );

			renderer.setRenderTarget( cubeUVRenderTarget );

			if ( useSolidColor ) {

				renderer.render( backgroundBox, cubeCamera );

			}

			renderer.render( scene, cubeCamera );

		}

		backgroundBox.geometry.dispose();
		backgroundBox.material.dispose();

		renderer.toneMapping = toneMapping;
		renderer.autoClear = originalAutoClear;
		scene.background = background;

	}

	_textureToCubeUV( texture, cubeUVRenderTarget ) {

		const renderer = this._renderer;

		const isCubeTexture = ( texture.mapping === CubeReflectionMapping || texture.mapping === CubeRefractionMapping );

		if ( isCubeTexture ) {

			if ( this._cubemapMaterial === null ) {

				this._cubemapMaterial = _getCubemapMaterial();

			}

			this._cubemapMaterial.uniforms.flipEnvMap.value = ( texture.isRenderTargetTexture === false ) ? - 1 : 1;

		} else {

			if ( this._equirectMaterial === null ) {

				this._equirectMaterial = _getEquirectMaterial();

			}

		}

		const material = isCubeTexture ? this._cubemapMaterial : this._equirectMaterial;
		const mesh = new Mesh( this._lodPlanes[ 0 ], material );

		const uniforms = material.uniforms;

		uniforms[ 'envMap' ].value = texture;

		const size = this._cubeSize;

		_setViewport( cubeUVRenderTarget, 0, 0, 3 * size, 2 * size );

		renderer.setRenderTarget( cubeUVRenderTarget );
		renderer.render( mesh, _flatCamera );

	}

	_applyPMREM( cubeUVRenderTarget ) {

		const renderer = this._renderer;
		const autoClear = renderer.autoClear;
		renderer.autoClear = false;
		const n = this._lodPlanes.length;

		for ( let i = 1; i < n; i ++ ) {

			const sigma = Math.sqrt( this._sigmas[ i ] * this._sigmas[ i ] - this._sigmas[ i - 1 ] * this._sigmas[ i - 1 ] );

			const poleAxis = _axisDirections[ ( n - i - 1 ) % _axisDirections.length ];

			this._blur( cubeUVRenderTarget, i - 1, i, sigma, poleAxis );

		}

		renderer.autoClear = autoClear;

	}

	/**
	 * This is a two-pass Gaussian blur for a cubemap. Normally this is done
	 * vertically and horizontally, but this breaks down on a cube. Here we apply
	 * the blur latitudinally (around the poles), and then longitudinally (towards
	 * the poles) to approximate the orthogonally-separable blur. It is least
	 * accurate at the poles, but still does a decent job.
	 */
	_blur( cubeUVRenderTarget, lodIn, lodOut, sigma, poleAxis ) {

		const pingPongRenderTarget = this._pingPongRenderTarget;

		this._halfBlur(
			cubeUVRenderTarget,
			pingPongRenderTarget,
			lodIn,
			lodOut,
			sigma,
			'latitudinal',
			poleAxis );

		this._halfBlur(
			pingPongRenderTarget,
			cubeUVRenderTarget,
			lodOut,
			lodOut,
			sigma,
			'longitudinal',
			poleAxis );

	}

	_halfBlur( targetIn, targetOut, lodIn, lodOut, sigmaRadians, direction, poleAxis ) {

		const renderer = this._renderer;
		const blurMaterial = this._blurMaterial;

		if ( direction !== 'latitudinal' && direction !== 'longitudinal' ) {

			console.error(
				'blur direction must be either latitudinal or longitudinal!' );

		}

		// Number of standard deviations at which to cut off the discrete approximation.
		const STANDARD_DEVIATIONS = 3;

		const blurMesh = new Mesh( this._lodPlanes[ lodOut ], blurMaterial );
		const blurUniforms = blurMaterial.uniforms;

		const pixels = this._sizeLods[ lodIn ] - 1;
		const radiansPerPixel = isFinite( sigmaRadians ) ? Math.PI / ( 2 * pixels ) : 2 * Math.PI / ( 2 * MAX_SAMPLES - 1 );
		const sigmaPixels = sigmaRadians / radiansPerPixel;
		const samples = isFinite( sigmaRadians ) ? 1 + Math.floor( STANDARD_DEVIATIONS * sigmaPixels ) : MAX_SAMPLES;

		if ( samples > MAX_SAMPLES ) {

			console.warn( `sigmaRadians, ${
				sigmaRadians}, is too large and will clip, as it requested ${
				samples} samples when the maximum is set to ${MAX_SAMPLES}` );

		}

		const weights = [];
		let sum = 0;

		for ( let i = 0; i < MAX_SAMPLES; ++ i ) {

			const x = i / sigmaPixels;
			const weight = Math.exp( - x * x / 2 );
			weights.push( weight );

			if ( i === 0 ) {

				sum += weight;

			} else if ( i < samples ) {

				sum += 2 * weight;

			}

		}

		for ( let i = 0; i < weights.length; i ++ ) {

			weights[ i ] = weights[ i ] / sum;

		}

		blurUniforms[ 'envMap' ].value = targetIn.texture;
		blurUniforms[ 'samples' ].value = samples;
		blurUniforms[ 'weights' ].value = weights;
		blurUniforms[ 'latitudinal' ].value = direction === 'latitudinal';

		if ( poleAx