three.js/src/renderers/shaders/ShaderChunk/transmission_fragment.glsl.js

export default /* glsl */`
#ifdef USE_TRANSMISSION

	float transmissionFactor = transmission;
	float thicknessFactor = thickness;

	#ifdef USE_TRANSMISSIONMAP

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

	#endif

	#ifdef USE_THICKNESSMAP

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

	#endif

	vec3 pos = vWorldPosition;
	vec3 v = normalize( cameraPosition - pos );
	vec3 n = inverseTransformDirection( normal, viewMatrix );

	vec3 transmission = getIBLVolumeRefraction(
		n, v, roughnessFactor, material.diffuseColor, material.specularColor, material.specularF90,
		pos, modelMatrix, viewMatrix, projectionMatrix, ior, thicknessFactor,
		attenuationTint, attenuationDistance );

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