le = bicubic( sampler, uv, vec4( fLodSizeInv, fLodSize ), floor( lod ) );\n\t\tvec4 cSample = bicubic( sampler, uv, vec4( cLodSizeInv, cLodSize ), ceil( lod ) );\n\t\treturn mix( fSample, cSample, fract( lod ) );\n\t}\n\tvec3 getVolumeTransmissionRay( const in vec3 n, const in vec3 v, const in float thickness, const in float ior, const in mat4 modelMatrix ) {\n\t\tvec3 refractionVector = refract( - v, normalize( n ), 1.0 / ior );\n\t\tvec3 modelScale;\n\t\tmodelScale.x = length( vec3( modelMatrix[ 0 ].xyz ) );\n\t\tmodelScale.y = length( vec3( modelMatrix[ 1 ].xyz ) );\n\t\tmodelScale.z = length( vec3( modelMatrix[ 2 ].xyz ) );\n\t\treturn normalize( refractionVector ) * thickness * modelScale;\n\t}\n\tfloat applyIorToRoughness( const in float roughness, const in float ior ) {\n\t\treturn roughness * clamp( ior * 2.0 - 2.0, 0.0, 1.0 );\n\t}\n\tvec4 getTransmissionSample( const in vec2 fragCoord, const in float roughness, const in float ior ) {\n\t\tfloat lod = log2( transmissionSamplerSize.x ) * applyIorToRoughness( roughness, ior );\n\t\treturn textureBicubic( transmissionSamplerMap, fragCoord.xy, lod );\n\t}\n\tvec3 volumeAttenuation( const in float transmissionDistance, const in vec3 attenuationColor, const in float attenuationDistance ) {\n\t\tif ( isinf( attenuationDistance ) ) {\n\t\t\treturn vec3( 1.0 );\n\t\t} else {\n\t\t\tvec3 attenuationCoefficient = -log( attenuationColor ) / attenuationDistance;\n\t\t\tvec3 transmittance = exp( - attenuationCoefficient * transmissionDistance );\t\t\treturn transmittance;\n\t\t}\n\t}\n\tvec4 getIBLVolumeRefraction( const in vec3 n, const in vec3 v, const in float roughness, const in vec3 diffuseColor,\n\t\tconst in vec3 specularColor, const in float specularF90, const in vec3 position, const in mat4 modelMatrix,\n\t\tconst in mat4 viewMatrix, const in mat4 projMatrix, const in float dispersion, const in float ior, const in float thickness,\n\t\tconst in vec3 attenuationColor, const in float attenuationDistance ) {\n\t\tvec4 transmittedLight;\n\t\tvec3 transmittance;\n\t\t#ifdef USE_DISPERSION\n\t\t\tfloat halfSpread = ( ior - 1.0 ) * 0.025 * dispersion;\n\t\t\tvec3 iors = vec3( ior - halfSpread, ior, ior + halfSpread );\n\t\t\tfor ( int i = 0; i < 3; i ++ ) {\n\t\t\t\tvec3 transmissionRay = getVolumeTransmissionRay( n, v, thickness, iors[ i ], modelMatrix );\n\t\t\t\tvec3 refractedRayExit = position + transmissionRay;\n\t\t\t\tvec4 ndcPos = projMatrix * viewMatrix * vec4( refractedRayExit, 1.0 );\n\t\t\t\tvec2 refractionCoords = ndcPos.xy / ndcPos.w;\n\t\t\t\trefractionCoords += 1.0;\n\t\t\t\trefractionCoords /= 2.0;\n\t\t\t\tvec4 transmissionSample = getTransmissionSample( refractionCoords, roughness, iors[ i ] );\n\t\t\t\ttransmittedLight[ i ] = transmissionSample[ i ];\n\t\t\t\ttransmittedLight.a += transmissionSample.a;\n\t\t\t\ttransmittance[ i ] = diffuseColor[ i ] * volumeAttenuation( length( transmissionRay ), attenuationColor, attenuationDistance )[ i ];\n\t\t\t}\n\t\t\ttransmittedLight.a /= 3.0;\n\t\t#else\n\t\t\tvec3 transmissionRay = getVolumeTransmissionRay( n, v, thickness, ior, modelMatrix );\n\t\t\tvec3 refractedRayExit = position + transmissionRay;\n\t\t\tvec4 ndcPos = projMatrix * viewMatrix * vec4( refractedRayExit, 1.0 );\n\t\t\tvec2 refractionCoords = ndcPos.xy / ndcPos.w;\n\t\t\trefractionCoords += 1.0;\n\t\t\trefractionCoords /= 2.0;\n\t\t\ttransmittedLight = getTransmissionSample( refractionCoords, roughness, ior );\n\t\t\ttransmittance = diffuseColor * volumeAttenuation( length( transmissionRay ), attenuationColor, attenuationDistance );\n\t\t#endif\n\t\tvec3 attenuatedColor = transmittance * transmittedLight.rgb;\n\t\tvec3 F = EnvironmentBRDF( n, v, specularColor, specularF90, roughness );\n\t\tfloat transmittanceFactor = ( transmittance.r + transmittance.g + transmittance.b ) / 3.0;\n\t\treturn vec4( ( 1.0 - F ) * attenuatedColor, 1.0 - ( 1.0 - transmittedLight.a ) * transmittanceFactor );\n\t}\n#endif"; var uv_pars_fragment = "#if defined( USE_UV ) || defined( USE_ANISOTROPY )\n\tvarying vec2 vUv;\n#endif\n#ifdef USE_MAP\n\tvarying vec2 vMapUv;\n#endif\n#ifdef USE_ALPHAMAP\n\tvarying vec2 vAlphaMapUv;\n#endif\n#ifdef USE_LIGHTMAP\n\tvarying vec2 vLightMapUv;\n#endif\n#ifdef USE_AOMAP\n\tvarying vec2 vAoMapUv;\n#endif\n#ifdef USE_BUMPMAP\n\tvarying vec2 vBumpMapUv;\n#endif\n#ifdef USE_NORMALMAP\n\tvarying vec2 vNormalMapUv;\n#endif\n#ifdef USE_EMISSIVEMAP\n\tvarying vec2 vEmissiveMapUv;\n#endif\n#ifdef USE_METALNESSMAP\n\tvarying vec2 vMetalnessMapUv;\n#endif\n#ifdef USE_ROUGHNESSMAP\n\tvarying vec2 vRoughnessMapUv;\n#endif\n#ifdef USE_ANISOTROPYMAP\n\tvarying vec2 vAnisotropyMapUv;\n#endif\n#ifdef USE_CLEARCOATMAP\n\tvarying vec2 vClearcoatMapUv;\n#endif\n#ifdef USE_CLEARCOAT_NORMALMAP\n\tvarying vec2 vClearcoatNormalMapUv;\n#endif\n#ifdef USE_CLEARCOAT_ROUGHNESSMAP\n\tvarying vec2 vClearcoatRoughnessMapUv;\n#endif\n#ifdef USE_IRIDESCENCEMAP\n\tvarying vec2 vIridescenceMapUv;\n#endif\n#