export default /* glsl */`
#if defined( USE_ENVMAP )

	#ifdef ENVMAP_MODE_REFRACTION
		uniform float refractionRatio;
	#endif

	vec3 getLightProbeIndirectIrradiance( /*const in SpecularLightProbe specularLightProbe,*/ const in GeometricContext geometry, const in int maxMIPLevel ) {

		vec3 worldNormal = inverseTransformDirection( geometry.normal, viewMatrix );

		#ifdef ENVMAP_TYPE_CUBE

			vec3 queryVec = vec3( flipEnvMap * worldNormal.x, worldNormal.yz );

			// TODO: replace with properly filtered cubemaps and access the irradiance LOD level, be it the last LOD level
			// of a specular cubemap, or just the default level of a specially created irradiance cubemap.

			#ifdef TEXTURE_LOD_EXT

				vec4 envMapColor = textureCubeLodEXT( envMap, queryVec, float( maxMIPLevel ) );

			#else

				// force the bias high to get the last LOD level as it is the most blurred.
				vec4 envMapColor = textureCube( envMap, queryVec, float( maxMIPLevel ) );

			#endif

			envMapColor.rgb = envMapTexelToLinear( envMapColor ).rgb;

		#elif defined( ENVMAP_TYPE_CUBE_UV )

			vec3 queryVec = vec3( flipEnvMap * worldNormal.x, worldNormal.yz );
			vec4 envMapColor = textureCubeUV( envMap, queryVec, 1.0 );

		#else

			vec4 envMapColor = vec4( 0.0 );

		#endif

		return PI * envMapColor.rgb * envMapIntensity;

	}

	// Trowbridge-Reitz distribution to Mip level, following the logic of http://casual-effects.blogspot.ca/2011/08/plausible-environment-lighting-in-two.html
	float getSpecularMIPLevel( const in float roughness, const in int maxMIPLevel ) {

		float maxMIPLevelScalar = float( maxMIPLevel );

		float sigma = PI * roughness * roughness / ( 1.0 + roughness );
		float desiredMIPLevel = maxMIPLevelScalar + log2( sigma );

		// clamp to allowable LOD ranges.
		return clamp( desiredMIPLevel, 0.0, maxMIPLevelScalar );

	}

	vec3 getLightProbeIndirectRadiance( /*const in SpecularLightProbe specularLightProbe,*/ const in vec3 viewDir, const in vec3 normal, const in float roughness, const in int maxMIPLevel ) {

		#ifdef ENVMAP_MODE_REFLECTION

		  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) );

		#else

		  vec3 reflectVec = refract( -viewDir, normal, refractionRatio );

		#endif

		reflectVec = inverseTransformDirection( reflectVec, viewMatrix );

		float specularMIPLevel = getSpecularMIPLevel( roughness, maxMIPLevel );

		#ifdef ENVMAP_TYPE_CUBE

			vec3 queryReflectVec = vec3( flipEnvMap * reflectVec.x, reflectVec.yz );

			#ifdef TEXTURE_LOD_EXT

				vec4 envMapColor = textureCubeLodEXT( envMap, queryReflectVec, specularMIPLevel );

			#else

				vec4 envMapColor = textureCube( envMap, queryReflectVec, specularMIPLevel );

			#endif

			envMapColor.rgb = envMapTexelToLinear( envMapColor ).rgb;

		#elif defined( ENVMAP_TYPE_CUBE_UV )

			vec3 queryReflectVec = vec3( flipEnvMap * reflectVec.x, reflectVec.yz );
			vec4 envMapColor = textureCubeUV( envMap, queryReflectVec, roughness );

		#elif defined( ENVMAP_TYPE_EQUIREC )

			vec2 sampleUV;
			sampleUV.y = asin( clamp( reflectVec.y, - 1.0, 1.0 ) ) * RECIPROCAL_PI + 0.5;
			sampleUV.x = atan( reflectVec.z, reflectVec.x ) * RECIPROCAL_PI2 + 0.5;

			#ifdef TEXTURE_LOD_EXT

				vec4 envMapColor = texture2DLodEXT( envMap, sampleUV, specularMIPLevel );

			#else

				vec4 envMapColor = texture2D( envMap, sampleUV, specularMIPLevel );

			#endif

			envMapColor.rgb = envMapTexelToLinear( envMapColor ).rgb;

		#elif defined( ENVMAP_TYPE_SPHERE )

			vec3 reflectView = normalize( ( viewMatrix * vec4( reflectVec, 0.0 ) ).xyz + vec3( 0.0,0.0,1.0 ) );

			#ifdef TEXTURE_LOD_EXT

				vec4 envMapColor = texture2DLodEXT( envMap, reflectView.xy * 0.5 + 0.5, specularMIPLevel );

			#else

				vec4 envMapColor = texture2D( envMap, reflectView.xy * 0.5 + 0.5, specularMIPLevel );

			#endif

			envMapColor.rgb = envMapTexelToLinear( envMapColor ).rgb;

		#endif

		return envMapColor.rgb * envMapIntensity;

	}

#endif
`;
