export default /* glsl */`
#ifdef USE_ENVMAP

	vec3 getIBLIrradiance( const in vec3 normal ) {

		#ifdef ENVMAP_TYPE_CUBE_UV

			vec3 worldNormal = inverseTransformDirection( normal, viewMatrix );

			vec4 envMapColor = textureCubeUV( envMap, envMapRotation * worldNormal, 1.0 );

			return PI * envMapColor.rgb * envMapIntensity;

		#else

			return vec3( 0.0 );

		#endif

	}

	vec3 getIBLRadiance( const in vec3 viewDir, const in vec3 normal, const in float roughness ) {

		#ifdef ENVMAP_TYPE_CUBE_UV

			vec3 reflectVec = reflect( - viewDir, normal );

			// Mixing the reflection with the normal is more accurate and keeps rough objects from gathering light from behind their tangent plane.
			reflectVec = normalize( mix( reflectVec, normal, roughness * roughness) );

			reflectVec = inverseTransformDirection( reflectVec, viewMatrix );

			vec4 envMapColor = textureCubeUV( envMap, envMapRotation * reflectVec, roughness );

			return envMapColor.rgb * envMapIntensity;

		#else

			return vec3( 0.0 );

		#endif

	}

	#ifdef USE_ANISOTROPY

		vec3 getIBLAnisotropyRadiance( const in vec3 viewDir, const in vec3 normal, const in float roughness, const in vec3 bitangent, const in float anisotropy ) {

			#ifdef ENVMAP_TYPE_CUBE_UV

			  // https://google.github.io/filament/Filament.md.html#lighting/imagebasedlights/anisotropy
				vec3 bentNormal = cross( bitangent, viewDir );
				bentNormal = normalize( cross( bentNormal, bitangent ) );
				bentNormal = normalize( mix( bentNormal, normal, pow2( pow2( 1.0 - anisotropy * ( 1.0 - roughness ) ) ) ) );

				return getIBLRadiance( viewDir, bentNormal, roughness );

			#else

				return vec3( 0.0 );

			#endif

		}

	#endif

#endif
`;