add basic clearcoat lobe

1 files changed, 59 insertions, 0 deletions

diff --git a/yum_brdf.cginc b/yum_brdf.cginc
index 52bc495..ab1730b 100644
--- a/yum_brdf.cginc
+++ b/yum_brdf.cginc
@@ -44,6 +44,22 @@ float3 specularLobe(YumPbr pbr, float f0,
   return (D * V) * F * PI;

 }

 

+#if defined(_CLEARCOAT)

+// Add a clearcoat specular lobe function

+float3 clearcoatLobe(float roughness, float f0,

+    float3 h, float LoH, float NoH_mesh, float NoV_mesh, float NoL_mesh)

+{

+  const float F = F_Schlick(f0, LoH);

+

+  // Normal distribution function with clearcoat roughness

+  float D = D_GGX(roughness, NoH_mesh, h);

+  // Geometric shadowing

+  float V = V_SmithGGXCorrelated_Fast(roughness, NoV_mesh, NoL_mesh);

+

+  return (D * V) * F * PI;

+}

+#endif  // _CLEARCOAT

+

 float4 YumBRDF(v2f i, const YumLighting light, YumPbr pbr) {

   const float3 h = normalize(light.view_dir + light.dir);

   const float LoH = saturate(dot(light.dir, h));

@@ -73,13 +89,49 @@ float4 YumBRDF(v2f i, const YumLighting light, YumPbr pbr) {
   const float3 E = specularDFG(dfg, f0);

   const float3 energy_compensation = energyCompensation(dfg, f0);

 

+#if defined(_CLEARCOAT)

+  // Clearcoat parameters

+  const float clearcoat_strength = _Clearcoat_Strength;

+  const float clearcoat_roughness = max(0.089, _Clearcoat_Roughness);

+  const float clearcoat_perceptual_roughness = sqrt(clearcoat_roughness);

+  

+  // IoR of 1.5 -> reflectance of 0.04

+  const float clearcoat_f0 = 0.04; 

+

+  // Use cc normal for clearcoat instead of detail normal

+  const float3 cc_normal = i.normal;

+  const float NoV_cc = max(1E-4, dot(cc_normal, light.view_dir));

+  const float NoH_cc = saturate(dot(cc_normal, h));

+  const float NoL_cc = saturate(dot(cc_normal, light.dir));

+#if defined(_WRAPPED_LIGHTING)

+  const float NoL_cc_wrapped = saturate((NoL_cc + light.wrapped) / (1.0 + light.wrapped));

+#else

+  const float NoL_cc_wrapped = NoL_cc;

+#endif

+  

+  // Calculate clearcoat DFG terms with cc normal

+  const float3 clearcoat_dfg = PrefilteredDFG_LUT(clearcoat_perceptual_roughness, NoV_cc);

+  const float clearcoat_E = specularDFG(clearcoat_dfg, clearcoat_f0);

+  const float clearcoat_energy_compensation = energyCompensation(clearcoat_dfg, clearcoat_f0);

+#endif  // _CLEARCOAT

+

   float3 direct;

   {

+    // Base layer

     float3 Fd = diffuseLobe(pbr.albedo, pbr.roughness_perceptual, LoH, NoL,

         NoV, f90);

     Fd *= (1.0 - pbr.metallic) * light.attenuation;

     float3 Fr = specularLobe(pbr, f0, h, LoH, NoH, NoV, NoL_wrapped_s);

+    

+#if defined(_CLEARCOAT)

+    float Fcr = clearcoatLobe(clearcoat_roughness, clearcoat_f0, h, LoH, NoH_cc, NoV_cc, NoL_cc_wrapped);

+    Fcr *= clearcoat_strength * clearcoat_energy_compensation; 

+    float clearcoat_factor = 1.0 - clearcoat_strength * F_Schlick(clearcoat_f0, NoV_cc);

+    float3 color = (Fd * NoL_wrapped_d + Fr * energy_compensation * NoL_wrapped_s) * clearcoat_factor + 

+                    Fcr * NoL_cc_wrapped;

+#else

     float3 color = Fd * NoL_wrapped_d + Fr * energy_compensation * NoL_wrapped_s;

+#endif  // _CLEARCOAT

 

     direct = color * light.direct;

   }

@@ -88,7 +140,14 @@ float4 YumBRDF(v2f i, const YumLighting light, YumPbr pbr) {
   {

     float3 Fr = E * light.specular * energy_compensation;

     float3 Fd = pbr.albedo * light.diffuse * (1.0 - E) * (1.0 - pbr.metallic) * pbr.ao;

+    

+#if defined(_CLEARCOAT)

+    float Fcr = clearcoat_E * light.specular * clearcoat_energy_compensation * clearcoat_strength;

+    float clearcoat_factor = 1.0 - clearcoat_strength * F_Schlick(clearcoat_f0, NoV_cc);

+    indirect = (Fr + Fd) * clearcoat_factor + Fcr;

+#else

     indirect = Fr + Fd;

+#endif  // _CLEARCOAT

   }

 

   return float4(direct + indirect, pbr.albedo.a);