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WebGLRenderer: Add clearcoat energy conservation #32145

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WebGLRenderer: Add clearcoat energy conservation #32145

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9d969ba
WebGLRenderer: Add clearcoat energy conservation.
mrdoob Oct 30, 2025
e2d4bc8
Clean up.
mrdoob Oct 30, 2025
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51 changes: 46 additions & 5 deletions src/renderers/shaders/ShaderChunk/lights_physical_pars_fragment.glsl.js
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Original file line number Diff line number Diff line change
Expand Up @@ -80,7 +80,7 @@ float V_GGX_SmithCorrelated( const in float alpha, const in float dotNL, const i

// Microfacet Models for Refraction through Rough Surfaces - equation (33)
// http://graphicrants.blogspot.com/2013/08/specular-brdf-reference.html
// alpha is "roughness squared" in Disney’s reparameterization
// alpha is "roughness squared" in Disney's reparameterization
float D_GGX( const in float alpha, const in float dotNH ) {

float a2 = pow2( alpha );
Expand Down Expand Up @@ -524,6 +524,18 @@ void RE_Direct_Physical( const in IncidentLight directLight, const in vec3 geome

clearcoatSpecularDirect += ccIrradiance * BRDF_GGX_Clearcoat( directLight.direction, geometryViewDir, geometryClearcoatNormal, material );

// Energy conservation: attenuate base layer by clearcoat reflectance
// Calculate clearcoat Fresnel for energy conservation
vec3 clearcoatHalfDir = normalize( directLight.direction + geometryViewDir );
float dotVHcc = saturate( dot( geometryViewDir, clearcoatHalfDir ) );
float clearcoatFresnel = F_Schlick( material.clearcoatF0.x, material.clearcoatF90, dotVHcc );

// Base layer attenuation: (1 - clearcoat * Fresnel)
float baseLayerAttenuation = 1.0 - material.clearcoat * clearcoatFresnel;

// Apply attenuation to base layer contributions
irradiance *= baseLayerAttenuation;

#endif

#ifdef USE_SHEEN
Expand All @@ -539,7 +551,20 @@ void RE_Direct_Physical( const in IncidentLight directLight, const in vec3 geome

void RE_IndirectDiffuse_Physical( const in vec3 irradiance, const in vec3 geometryPosition, const in vec3 geometryNormal, const in vec3 geometryViewDir, const in vec3 geometryClearcoatNormal, const in PhysicalMaterial material, inout ReflectedLight reflectedLight ) {

reflectedLight.indirectDiffuse += irradiance * BRDF_Lambert( material.diffuseColor );
#ifdef USE_CLEARCOAT

// Energy conservation: attenuate indirect diffuse by clearcoat reflectance
float dotNVcc = saturate( dot( geometryClearcoatNormal, geometryViewDir ) );
float clearcoatFresnelIndirect = F_Schlick( material.clearcoatF0.x, material.clearcoatF90, dotNVcc );
float baseLayerAttenuationIndirect = 1.0 - material.clearcoat * clearcoatFresnelIndirect;

reflectedLight.indirectDiffuse += irradiance * BRDF_Lambert( material.diffuseColor ) * baseLayerAttenuationIndirect;

#else

reflectedLight.indirectDiffuse += irradiance * BRDF_Lambert( material.diffuseColor );

#endif

}

Expand Down Expand Up @@ -576,10 +601,26 @@ void RE_IndirectSpecular_Physical( const in vec3 radiance, const in vec3 irradia
vec3 totalScattering = singleScattering + multiScattering;
vec3 diffuse = material.diffuseColor * ( 1.0 - max( max( totalScattering.r, totalScattering.g ), totalScattering.b ) );

reflectedLight.indirectSpecular += radiance * singleScattering;
reflectedLight.indirectSpecular += multiScattering * cosineWeightedIrradiance;
#ifdef USE_CLEARCOAT

// Energy conservation: attenuate indirect specular by clearcoat reflectance
float dotNVcc = saturate( dot( geometryClearcoatNormal, geometryViewDir ) );
float clearcoatFresnelIndirect = F_Schlick( material.clearcoatF0.x, material.clearcoatF90, dotNVcc );
float baseLayerAttenuationIndirect = 1.0 - material.clearcoat * clearcoatFresnelIndirect;

reflectedLight.indirectSpecular += radiance * singleScattering * baseLayerAttenuationIndirect;
reflectedLight.indirectSpecular += multiScattering * cosineWeightedIrradiance * baseLayerAttenuationIndirect;

reflectedLight.indirectDiffuse += diffuse * cosineWeightedIrradiance * baseLayerAttenuationIndirect;

#else

reflectedLight.indirectDiffuse += diffuse * cosineWeightedIrradiance;
reflectedLight.indirectSpecular += radiance * singleScattering;
reflectedLight.indirectSpecular += multiScattering * cosineWeightedIrradiance;

reflectedLight.indirectDiffuse += diffuse * cosineWeightedIrradiance;

#endif

}

Expand Down