From b11eecd7e4bf9cd5d1cdf95a5e995a39c59ca4bf Mon Sep 17 00:00:00 2001
From: yum <yum.food.vr@gmail.com>
Date: Tue, 11 Nov 2025 17:04:08 -0800
Subject: cc energy compensation

---
 brdf.cginc     | 22 ++++++++++++++++++----
 lighting.cginc |  3 +--
 2 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/brdf.cginc b/brdf.cginc
index 46b28e8..3a0db4c 100644
--- a/brdf.cginc
+++ b/brdf.cginc
@@ -145,6 +145,20 @@ float4 brdf(Pbr pbr, LightData data) {
     dfg = float3(1, 1, 1);
   }
 
+#if defined(_CLEARCOAT)
+  const float cc_f0 = 0.04f;
+  float2 cc_dfg_uv = float2(pbr.cc_roughness, data.common.NoV_cc);
+  float3 cc_dfg;
+  [branch]
+  if (textureExists(_DFG_LUT)) {
+    cc_dfg = _DFG_LUT.SampleLevel(bilinear_clamp_s, cc_dfg_uv, 0).rgb;
+  } else {
+    cc_dfg = float3(1, 1, 1);
+  }
+  float cc_Ess = max(cc_dfg.y, 1e-4f);
+  float cc_energy_comp = 1.0f + cc_f0 * (rcp(cc_Ess) - 1.0f);
+#endif
+
   float3 F0_color = lerp(float3(f0, f0, f0), pbr.albedo.xyz, pbr.metallic);
 
   // Direct
@@ -152,12 +166,12 @@ float4 brdf(Pbr pbr, LightData data) {
     float3 remainder = 1.0f;
 
 #if defined(_CLEARCOAT)
-    float cc_f0 = 0.04f;
     float Fcc = F_Schlick(data.direct.LoH, cc_f0, f90);
     float Dcc = D_GGX(pbr.cc_roughness, data.direct.NoH_cc);
     float Gcc = G_GGXSmith(pbr.cc_roughness, data.direct.NoL_cc, data.common.NoV_cc);
     float DFGcc = Fcc * Dcc * Gcc;
     float3 direct_specular_cc = DFGcc * data.direct.color * data.direct.NoL_cc * pbr.cc_strength;
+    direct_specular_cc *= cc_energy_comp;
     direct_specular_cc = max(0, direct_specular_cc);
     specular += direct_specular_cc;
     remainder = saturate(remainder - direct_specular_cc);
@@ -203,9 +217,9 @@ float4 brdf(Pbr pbr, LightData data) {
     float3 remainder = 1.0f;
 
 #if defined(_CLEARCOAT)
-    float cc_f0 = 0.04f;
-    float Fcc = F_Schlick(data.common.NoV, cc_f0, 1.0f);
-    float3 indirect_specular_cc = Fcc * data.indirect.specular_cc * pbr.cc_strength;
+    float cc_single_scatter = cc_f0 * cc_dfg.x + cc_dfg.y;
+    float3 indirect_specular_cc = data.indirect.specular_cc * (cc_single_scatter * cc_energy_comp) * pbr.cc_strength;
+    indirect_specular_cc = max(0, indirect_specular_cc);
     specular += indirect_specular_cc;
     remainder = saturate(remainder - indirect_specular_cc);
 #endif
diff --git a/lighting.cginc b/lighting.cginc
index cb3160a..4e5a61b 100644
--- a/lighting.cginc
+++ b/lighting.cginc
@@ -198,7 +198,7 @@ void GetLighting(v2f i, Pbr pbr, out LightData data) {
   data.indirect.LoH_cc = saturate(dot(dir_cc, H_cc));
 #endif
   data.indirect.LoH = saturate(dot(data.indirect.dir, data.indirect.H));
-  float indirect_LoV = dot(data.direct.dir, data.common.V);
+  float indirect_LoV = dot(data.indirect.dir, data.common.V);
   data.indirect.LoV = saturate(indirect_LoV);
   data.indirect.double_LoV = saturate(2.0f * indirect_LoV * indirect_LoV - 1.0f);
 
@@ -214,4 +214,3 @@ void GetLighting(v2f i, Pbr pbr, out LightData data) {
 }
 
 #endif  // __LIGHTING_INC
-
-- 
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