export default /* glsl */`
struct PhysicalMaterial {
vec3 diffuseColor;
float specularRoughness;
vec3 specularColor;
#ifdef CLEARCOAT
float clearcoat;
float clearcoatRoughness;
#endif
#ifdef USE_SHEEN
vec3 sheenColor;
#endif
};
#define MAXIMUM_SPECULAR_COEFFICIENT 0.16
#define DEFAULT_SPECULAR_COEFFICIENT 0.04
// Clear coat directional hemishperical reflectance (this approximation should be improved)
float clearcoatDHRApprox( const in float roughness, const in float dotNL ) {
return DEFAULT_SPECULAR_COEFFICIENT + ( 1.0 - DEFAULT_SPECULAR_COEFFICIENT ) * ( pow( 1.0 - dotNL, 5.0 ) * pow( 1.0 - roughness, 2.0 ) );
}
#if NUM_RECT_AREA_LIGHTS > 0
void RE_Direct_RectArea_Physical( const in RectAreaLight rectAreaLight, const in GeometricContext geometry, const in PhysicalMaterial material, inout ReflectedLight reflectedLight ) {
vec3 normal = geometry.normal;
vec3 viewDir = geometry.viewDir;
vec3 position = geometry.position;
vec3 lightPos = rectAreaLight.position;
vec3 halfWidth = rectAreaLight.halfWidth;
vec3 halfHeight = rectAreaLight.halfHeight;
vec3 lightColor = rectAreaLight.color;
float roughness = material.specularRoughness;
vec3 rectCoords[ 4 ];
rectCoords[ 0 ] = lightPos + halfWidth - halfHeight; // counterclockwise; light shines in local neg z direction
rectCoords[ 1 ] = lightPos - halfWidth - halfHeight;
rectCoords[ 2 ] = lightPos - halfWidth + halfHeight;
rectCoords[ 3 ] = lightPos + halfWidth + halfHeight;
vec2 uv = LTC_Uv( normal, viewDir, roughness );
vec4 t1 = texture2D( ltc_1, uv );
vec4 t2 = texture2D( ltc_2, uv );
mat3 mInv = mat3(
vec3( t1.x, 0, t1.y ),
vec3( 0, 1, 0 ),
vec3( t1.z, 0, t1.w )
);
// LTC Fresnel Approximation by Stephen Hill
// http://blog.selfshadow.com/publications/s2016-advances/s2016_ltc_fresnel.pdf
vec3 fresnel = ( material.specularColor * t2.x + ( vec3( 1.0 ) - material.specularColor ) * t2.y );
reflectedLight.directSpecular += lightColor * fresnel * LTC_Evaluate( normal, viewDir, position, mInv, rectCoords );
reflectedLight.directDiffuse += lightColor * material.diffuseColor * LTC_Evaluate( normal, viewDir, position, mat3( 1.0 ), rectCoords );
}
#endif
void RE_Direct_Physical( const in IncidentLight directLight, const in GeometricContext geometry, const in PhysicalMaterial material, inout ReflectedLight reflectedLight ) {
float dotNL = saturate( dot( geometry.normal, directLight.direction ) );
vec3 irradiance = dotNL * directLight.color;
#ifndef PHYSICALLY_CORRECT_LIGHTS
irradiance *= PI; // punctual light
#endif
#ifdef CLEARCOAT
float ccDotNL = saturate( dot( geometry.clearcoatNormal, directLight.direction ) );
vec3 ccIrradiance = ccDotNL * directLight.color;
#ifndef PHYSICALLY_CORRECT_LIGHTS
ccIrradiance *= PI; // punctual light
#endif
float clearcoatDHR = material.clearcoat * clearcoatDHRApprox( material.clearcoatRoughness, ccDotNL );
reflectedLight.directSpecular += ccIrradiance * material.clearcoat * BRDF_Specular_GGX( directLight, geometry.viewDir, geometry.clearcoatNormal, vec3( DEFAULT_SPECULAR_COEFFICIENT ), material.clearcoatRoughness );
#else
float clearcoatDHR = 0.0;
#endif
#ifdef USE_SHEEN
reflectedLight.directSpecular += ( 1.0 - clearcoatDHR ) * irradiance * BRDF_Specular_Sheen(
material.specularRoughness,
directLight.direction,
geometry,
material.sheenColor
);
#else
reflectedLight.directSpecular += ( 1.0 - clearcoatDHR ) * irradiance * BRDF_Specular_GGX( directLight, geometry.viewDir, geometry.normal, material.specularColor, material.specularRoughness);
#endif
reflectedLight.directDiffuse += ( 1.0 - clearcoatDHR ) * irradiance * BRDF_Diffuse_Lambert( material.diffuseColor );
}
void RE_IndirectDiffuse_Physical( const in vec3 irradiance, const in GeometricContext geometry, const in PhysicalMaterial material, inout ReflectedLight reflectedLight ) {
reflectedLight.indirectDiffuse += irradiance * BRDF_Diffuse_Lambert( material.diffuseColor );
}
void RE_IndirectSpecular_Physical( const in vec3 radiance, const in vec3 irradiance, const in vec3 clearcoatRadiance, const in GeometricContext geometry, const in PhysicalMaterial material, inout ReflectedLight reflectedLight) {
#ifdef CLEARCOAT
float ccDotNV = saturate( dot( geometry.clearcoatNormal, geometry.viewDir ) );
reflectedLight.indirectSpecular += clearcoatRadiance * material.clearcoat * BRDF_Specular_GGX_Environment( geometry.viewDir, geometry.clearcoatNormal, vec3( DEFAULT_SPECULAR_COEFFICIENT ), material.clearcoatRoughness );
float ccDotNL = ccDotNV;
float clearcoatDHR = material.clearcoat * clearcoatDHRApprox( material.clearcoatRoughness, ccDotNL );
#else
float clearcoatDHR = 0.0;
#endif
float clearcoatInv = 1.0 - clearcoatDHR;
// Both indirect specular and indirect diffuse light accumulate here
vec3 singleScattering = vec3( 0.0 );
vec3 multiScattering = vec3( 0.0 );
vec3 cosineWeightedIrradiance = irradiance * RECIPROCAL_PI;
BRDF_Specular_Multiscattering_Environment( geometry, material.specularColor, material.specularRoughness, singleScattering, multiScattering );
vec3 diffuse = material.diffuseColor * ( 1.0 - ( singleScattering + multiScattering ) );
reflectedLight.indirectSpecular += clearcoatInv * radiance * singleScattering;
reflectedLight.indirectSpecular += multiScattering * cosineWeightedIrradiance;
reflectedLight.indirectDiffuse += diffuse * cosineWeightedIrradiance;
}
#define RE_Direct RE_Direct_Physical
#define RE_Direct_RectArea RE_Direct_RectArea_Physical
#define RE_IndirectDiffuse RE_IndirectDiffuse_Physical
#define RE_IndirectSpecular RE_IndirectSpecular_Physical
// ref: https://seblagarde.files.wordpress.com/2015/07/course_notes_moving_frostbite_to_pbr_v32.pdf
float computeSpecularOcclusion( const in float dotNV, const in float ambientOcclusion, const in float roughness ) {
return saturate( pow( dotNV + ambientOcclusion, exp2( - 16.0 * roughness - 1.0 ) ) - 1.0 + ambientOcclusion );
}
`;