bsdfData.bitangentWS = cross(bsdfData.normalWS, bsdfData.tangentWS);
}
void FillMaterialIridescence(float thickness, inout BSDFData bsdfData)
void FillMaterialIridescence(float Dinc, float thicknessIrid, inout BSDFData bsdfData)
bsdfData.thickness = thickness;
bsdfData.Dinc = Dinc;
bsdfData.thicknessIrid = thicknessIrid;
}
// Note: this modify the parameter perceptualRoughness and fresnel0, so they need to be setup
if (HasMaterialFeatureFlag(surfaceData.materialFeatures, MATERIALFEATUREFLAGS_LIT_IRIDESCENCE))
{
FillMaterialIridescence(surfaceData.thicknessIrid, bsdfData);
FillMaterialIridescence(surfaceData.Dinc, surfaceData. thicknessIrid, bsdfData);
}
if (HasMaterialFeatureFlag(surfaceData.materialFeatures, MATERIALFEATUREFLAGS_LIT_CLEAR_COAT))
else if (HasMaterialFeatureFlag(surfaceData.materialFeatures, MATERIALFEATUREFLAGS_LIT_IRIDESCENCE))
{
metallic15 = GBUFFER_LIT_IRIDESCENCE;
outGBuffer2.rgb = float3(0.0 , surfaceData.thicknessIrid, 0.0);
outGBuffer2.rgb = float3(surfaceData.Dinc , surfaceData.thicknessIrid, 0.0);
}
else
{
if (HasMaterialFeatureFlag(bsdfData.materialFeatures, MATERIALFEATUREFLAGS_LIT_IRIDESCENCE))
{
FillMaterialIridescence(inGBuffer2.g, bsdfData);
FillMaterialIridescence(inGBuffer2.r, inGBuffer2. g, bsdfData);
}
if (HasMaterialFeatureFlag(bsdfData.materialFeatures, MATERIALFEATUREFLAGS_LIT_CLEAR_COAT))
}
//-----------------------------------------------------------------------------
// Iridescence
//-----------------------------------------------------------------------------
// Evaluation XYZ sensitivity curves in Fourier space
float3 EvalSensitivity(float opd, float shift)
{
// Use Gaussian fits, given by 3 parameters: val, pos and var
float phase = 2.0 * PI * opd * 1e-6;
float3 val = float3(5.4856e-13, 4.4201e-13, 5.2481e-13);
float3 pos = float3(1.6810e+06, 1.7953e+06, 2.2084e+06);
float3 var = float3(4.3278e+09, 9.3046e+09, 6.6121e+09);
float3 xyz = val * sqrt(2.0 * PI * var) * cos(pos * phase + shift) * exp(-var * phase * phase);
xyz.x += 9.7470e-14 * sqrt(2.0 * PI * 4.5282e+09) * cos(2.2399e+06 * phase + shift) * exp(-4.5282e+09 * phase * phase);
return xyz / 1.0685e-7;
}
// Evaluate the reflectance for a thin-film layer on top of a dielectric medum.
float3 EvalIridescence(float cosTheta1, BSDFData bsdfData)
{
float Dinc = 3.0 * bsdfData.Dinc;
// Indices of refraction
// Force eta_2 -> 1.0 when Dinc -> 0.0
float eta2 = lerp(2.0, 1.0, bsdfData.thicknessIrid);
float eta_2 = lerp(1.0, eta2, smoothstep(0.0, 0.03, Dinc));
float R0 = Sq((1.0 - eta_2) / (1.0 + eta_2));
//float eta_3 = 1.5;
// Evaluate the cosTheta on the base layer
float cosTheta2 = sqrt(1.0 - Sq(1.0 / eta_2)*(1 - Sq(cosTheta1)));
// First interface
float3 R12 = F_Schlick(R0, cosTheta1);
float3 R21 = R12;
float3 T121 = float3(1.0, 1.0, 1.0) - R12;
float phi12 = 0.0;
float phi21 = PI - phi12;
// Second interface
float3 R23 = F_Schlick(bsdfData.fresnel0, cosTheta2);
float phi23 = 0.0;
// Phase shift
float OPD = Dinc*cosTheta2;
float phi = phi21 + phi23;
// Compound terms
float3 R123 = R12*R23;
float3 r123 = sqrt(R123);
float3 Rs = Sq(T121)*R23 / (float3(1., 1., 1.) - R123);
float3 Cm = Rs - T121;
// Reflectance term for m=0 (DC term amplitude)
float3 C0 = R12 + Rs;
float3 I = C0;
// Reflectance term for m>0 (pairs of diracs)
for (int m = 1; m <= 2; ++m)
{
Cm *= r123;
float3 Sm = 2.0 * EvalSensitivity(m*OPD, m*phi);
I += Cm*Sm;
}
return I;
}
//-----------------------------------------------------------------------------
// PreLightData
//-----------------------------------------------------------------------------
float NdotV = saturate(dot(N, V));
preLightData.clampNdotV = NdotV; // Caution: The handling of edge cases where N is directed away from the screen is handled during Gbuffer/forward pass, so here do nothing
preLightData.iblPerceptualRoughness = bsdfData.perceptualRoughness;
float3 fresnel0 = bsdfData.fresnel0;
if (HasMaterialFeatureFlag(bsdfData.materialFeatures, MATERIALFEATUREFLAGS_LIT_IRIDESCENCE))
{
fresnel0 = EvalIridescence(NdotV, bsdfData);
}
if (HasMaterialFeatureFlag(bsdfData.materialFeatures, MATERIALFEATUREFLAGS_LIT_CLEAR_COAT))
{
// Handle IBL + multiscattering
float reflectivity;
GetPreIntegratedFGD(NdotV, preLightData.iblPerceptualRoughness, bsdfData. fresnel0, preLightData.specularFGD, preLightData.diffuseFGD, reflectivity);
GetPreIntegratedFGD(NdotV, preLightData.iblPerceptualRoughness, fresnel0, preLightData.specularFGD, preLightData.diffuseFGD, reflectivity);
iblR = reflect(-V, iblN);
// This is a ad-hoc tweak to better match reference of anisotropic GGX.
// TODO: the fit seems rather poor. The scaling factor of 0.5 allows us
// to match the reference for rough metals, but further darkens dielectrics.
preLightData.ltcMagnitudeFresnel = bsdfData. fresnel0 * ltcGGXFresnelMagnitudeDiff + (float3)ltcGGXFresnelMagnitude;
preLightData.ltcMagnitudeFresnel = fresnel0 * ltcGGXFresnelMagnitudeDiff + (float3)ltcGGXFresnelMagnitude;
if (HasMaterialFeatureFlag(bsdfData.materialFeatures, MATERIALFEATUREFLAGS_LIT_CLEAR_COAT))
{
float NdotH = saturate((NdotL + NdotV) * invLenLV);
float LdotH = saturate(invLenLV * LdotV + invLenLV);
float3 F = F_Schlick(bsdfData.fresnel0, LdotH);
float3 F;
if (HasMaterialFeatureFlag(bsdfData.materialFeatures, MATERIALFEATUREFLAGS_LIT_IRIDESCENCE))
{
F = EvalIridescence(LdotH, bsdfData);
}
else
{
F = F_Schlick(bsdfData.fresnel0, LdotH);
}
float DV;
if (HasMaterialFeatureFlag(bsdfData.materialFeatures, MATERIALFEATUREFLAGS_LIT_ANISOTROPY))
{
DV = DV_SmithJointGGX(NdotH, NdotL, NdotV, bsdfData.roughnessT, preLightData.partLambdaV);
}
specularLighting = F * DV;
#ifdef LIT_DIFFUSE_LAMBERT_BRDF
Sebastien Lagarde
7 年前