export default /* glsl */`
#ifdef USE_TRANSMISSION

	float transmissionFactor = transmission;
	float thicknessFactor = thickness;

	#ifdef USE_TRANSMISSIONMAP

		transmissionFactor *= texture2D( transmissionMap, vUv ).r;

	#endif

	#ifdef USE_THICKNESSNMAP

		thicknessFactor *= texture2D( thicknessMap, vUv ).g;

	#endif

	vec3 pos = vWorldPosition.xyz / vWorldPosition.w;
	vec3 v = normalize( cameraPosition - pos );
	float ior = ( 1.0 + 0.4 * reflectivity ) / ( 1.0 - 0.4 * reflectivity );

	vec3 transmission = transmissionFactor * getIBLVolumeRefraction(
		normal, v, roughnessFactor, material.diffuseColor, totalSpecular,
		pos, modelMatrix, viewMatrix, projectionMatrix, ior, thicknessFactor,
		attenuationColor, attenuationDistance );

	totalDiffuse = mix( totalDiffuse, transmission, transmissionFactor );
#endif
`;