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PBR precomputations

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This commit is contained in:
Emmanuel BENOîT 2017-10-05 15:28:33 +02:00
parent ba7595d781
commit 290555ad53
2 changed files with 74 additions and 36 deletions
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97
shaders/lib/shading-pbr.glsl
View file

@ -13,6 +13,12 @@ struct T_PBRMaterial
float specularTint; // Albedo color% in specular tint (non-metals)
};
struct T_PBRPrecomputed
{
float nDotV , ax , ay , fv , vgs;
vec3 tangent , bitangent , cSpecular;
};
// -----------------------------------------------------------------------------
float PBR_SchlickFresnel(
@ -46,66 +52,93 @@ float PBR_SmithGGXAniso(
return 1 / ( nDotV + sqrt( x * x + y * y + nDotV * nDotV ) );
}
T_PBRPrecomputed PBR_Precompute(
in T_PBRMaterial material ,
in vec3 camDir ,
in vec3 normal )
{
T_PBRPrecomputed rv;
rv.nDotV = dot( normal , camDir );
rv.fv = PBR_SchlickFresnel( rv.nDotV );
float tDir = step( .99 , abs( normal.z ) ) ,
aspect = sqrt( 1 - material.anisotropy * .9 ) ,
rsqr = material.roughness * material.roughness;
vec3 tUp = mix( vec3( 0 , 0 , 1 ) , vec3( 1 , 0 , 0 ) , tDir ) ,
tint = M_NormalizeColor( material.cAlbedo );
rv.tangent = normalize( cross( tUp , normal ) );
rv.bitangent = normalize( cross( normal , rv.tangent ) );
rv.cSpecular = mix(
material.specular * .08 * mix(
vec3( 1 ) , tint , material.specularTint ) ,
material.cAlbedo , material.metallic );
rv.ax = max( .001, rsqr / aspect );
rv.ay = max( .001, rsqr * aspect );
rv.vgs = PBR_SmithGGXAniso( rv.nDotV ,
dot( camDir , rv.tangent ) , dot( camDir , rv.bitangent ) ,
rv.ax , rv.ay );
return rv;
}
vec3 PBR_Shade(
in T_PBRMaterial material ,
in T_PBRPrecomputed pre ,
in vec3 camDir ,
in vec3 normal ,
in vec3 lightDir )
{
float nDotL = dot( normal , lightDir ) ,
nDotV = dot( normal , camDir );
if ( nDotL < 0 || nDotV < 0 ) {
float nDotL = dot( normal , lightDir );
if ( nDotL < 0 || pre.nDotV < 0 ) {
return vec3( 0 );
}
vec3 tangent = cross( vec3( 0 , 1 , 0 ) , normal );
if ( length( tangent ) == 0 ) {
tangent = cross( vec3( 1 , 0 , 0 ) , normal );
}
tangent = normalize( tangent );
vec3 bitangent = normalize( cross( normal , tangent ) );
vec3 halfVec = normalize( lightDir + camDir ) ,
tint = M_NormalizeColor( material.cAlbedo ) ,
cSpecular = mix( material.specular * .08 * mix(
vec3( 1 ) , tint , material.specularTint ) ,
material.cAlbedo , material.metallic );
//vec3 Csheen = mix(vec3(1), Ctint, sheenTint);
vec3 halfVec = normalize( lightDir + camDir ) ;
float nDotH = dot( normal , halfVec ) ,
lDotH = dot( lightDir , halfVec ) ,
// Diffuse fresnel - go from 1 at normal incidence to .5 at grazing
// and mix in diffuse retro-reflection based on roughness
FL = PBR_SchlickFresnel( nDotL ) ,
FV = PBR_SchlickFresnel( nDotV ) ,
Fd90 = 0.5 + 2 * lDotH * lDotH * material.roughness ,
Fd = mix( 1 , Fd90 , FL ) * mix( 1 , Fd90 , FV ) ,
Fd = mix( 1 , Fd90 , FL ) * mix( 1 , Fd90 , pre.fv ) ,
// Based on Hanrahan-Krueger brdf approximation of isotropic bssrdf
// 1.25 scale is used to (roughly) preserve albedo
// Fss90 used to "flatten" retroreflection based on roughness
Fss90 = lDotH * lDotH * material.roughness ,
Fss = mix( 1 , Fss90 , FL ) * mix( 1 , Fss90 , FV ) ,
ss = 1.25 * ( Fss * ( 1 / ( nDotL + nDotV ) - .5 ) + .5 ) ,
Fss = mix( 1 , Fss90 , FL ) * mix( 1 , Fss90 , pre.fv ) ,
ss = 1.25 * ( Fss * ( 1 / ( nDotL + pre.nDotV ) - .5 ) + .5 ) ,
// Specular
aspect = sqrt( 1 - material.anisotropy * .9 ) ,
rsqr = material.roughness * material.roughness ,
ax = max( .001, rsqr / aspect ) ,
ay = max( .001, rsqr * aspect ) ,
Ds = PBR_GTR2Aniso( nDotH , dot( halfVec , tangent ) ,
dot( halfVec , bitangent ) , ax , ay ) ,
Ds = PBR_GTR2Aniso( nDotH , dot( halfVec , pre.tangent ) ,
dot( halfVec , pre.bitangent ) ,
pre.ax , pre.ay ) ,
FH = PBR_SchlickFresnel( lDotH ) ,
Gs = PBR_SmithGGXAniso( nDotL , dot( lightDir , tangent ) ,
dot( lightDir , bitangent ) , ax , ay )
* PBR_SmithGGXAniso( nDotV , dot( camDir , tangent ) ,
dot( camDir , bitangent ) , ax , ay );
Gs = PBR_SmithGGXAniso( nDotL , dot( lightDir , pre.tangent ) ,
dot( lightDir , pre.bitangent ) ,
pre.ax , pre.ay ) * pre.vgs;
vec3 Fs = mix( cSpecular , vec3(1) , FH );
vec3 Fs = mix( pre.cSpecular , vec3(1) , FH );
return nDotL * ( ( ( 1 / PI )
* mix( Fd , ss , material.subsurface )
* material.cAlbedo /* + Fsheen */)
* pow( 1 - material.metallic , 3 )
+ clamp( Gs , 0 , 1 ) * Fs * Ds );
}
vec3 PBR_Shade(
in T_PBRMaterial material ,
in vec3 camDir ,
in vec3 normal ,
in vec3 lightDir )
{
return PBR_Shade(
material ,
PBR_Precompute( material , camDir , normal ) ,
camDir , normal , lightDir );
}

13
shaders/scene.f.glsl
View file

@ -65,6 +65,7 @@ vec2 RM_Map( vec3 pos )
vec3 pointlight(
in T_PBRMaterial material ,
in T_PBRPrecomputed pre ,
in vec3 hitPos ,
in vec3 rayDir ,
in vec3 normal ,
@ -79,7 +80,7 @@ vec3 pointlight(
}
return lightColor * lPwr * PBR_Shade(
material , -rayDir , normal , lightRay );
material , pre , -rayDir , normal , lightRay );
}
@ -123,11 +124,15 @@ void main( )
-rayDir , normal , sunlightDir );
} else {
T_PBRMaterial mat = PBRMaterials[ mtidx ];
bc = sunlightColor * PBR_Shade( mat ,
T_PBRPrecomputed pre = PBR_Precompute(
mat , -rayDir , normal );
bc = sunlightColor * PBR_Shade( mat , pre ,
-rayDir , normal , sunlightDir );
bc += pointlight( mat , hitPos , rayDir , normal ,
bc += pointlight( mat , pre ,
hitPos , rayDir , normal ,
pl1Pos , pl1Color , pl1Power );
bc += pointlight( mat , hitPos , rayDir , normal ,
bc += pointlight( mat , pre ,
hitPos , rayDir , normal ,
pl2Pos , pl2Color , pl2Power );
}