fix rough material energy compensation

1 files changed, 18 insertions, 10 deletions

diff --git a/brdf.cginc b/brdf.cginc
index 8352c08..1cb4d33 100644
--- a/brdf.cginc
+++ b/brdf.cginc
@@ -136,6 +136,17 @@ float4 brdf(Pbr pbr, LightData data) {
   data.direct.LoH = 1;
 #endif
 
+  float2 dfg_uv = float2(pbr.roughness, data.common.NoV);
+  float3 dfg;
+  [branch]
+  if (textureExists(_DFG_LUT)) {
+    dfg = _DFG_LUT.SampleLevel(bilinear_clamp_s, dfg_uv, 0).rgb;
+  } else {
+    dfg = float3(1, 1, 1);
+  }
+
+  float3 F0_color = lerp(float3(f0, f0, f0), pbr.albedo.xyz, pbr.metallic);
+
   // Direct
   {
     float3 remainder = 1.0f;
@@ -169,8 +180,13 @@ float4 brdf(Pbr pbr, LightData data) {
     float G = G_GGXSmith(pbr.roughness, data.direct.NoL, data.common.NoV);
 
     float FDG = F * D * G;
+    FDG = FDG * dfg.x + dfg.y;
 
     float3 direct_specular = FDG * remainder * data.direct.color * data.direct.NoL * lerp(1.0f, pbr.albedo.xyz, pbr.metallic);
+    float Ess = max(dfg.y, 1e-4f);
+    float invEss = rcp(Ess);
+    float3 energy_comp = 1.0f + F0_color * (invEss - 1.0f);
+    direct_specular *= energy_comp;
     direct_specular = max(0, direct_specular);
     specular += direct_specular;
     remainder = saturate(remainder - direct_specular);
@@ -182,10 +198,9 @@ float4 brdf(Pbr pbr, LightData data) {
   }
 
   // Indirect
-#if defined(FORWARD_BASE_PASS)
+#if !defined(FURNACE_TEST_DIRECT) && defined(FORWARD_BASE_PASS)
   {
     float3 remainder = 1.0f;
-    float2 dfg_uv = float2(pbr.roughness, data.common.NoV);
 
 #if defined(_CLEARCOAT)
     float cc_f0 = 0.04f;
@@ -207,13 +222,6 @@ float4 brdf(Pbr pbr, LightData data) {
 
     // Standard PBR IBL using split-sum approximation
     // Specular lobe
-    float2 dfg;
-    [branch]
-    if (textureExists(_DFG_LUT)) {
-      dfg = _DFG_LUT.SampleLevel(bilinear_clamp_s, dfg_uv, 0).rg;
-    } else {
-      dfg = float2(0, 1);
-    }
     float3 f0_spec = lerp(f0, pbr.albedo.xyz, pbr.metallic);
     float3 ibl_specular_reflectance = f0_spec * dfg.x + dfg.y;
     float3 indirect_specular = data.indirect.specular * ibl_specular_reflectance;
@@ -223,7 +231,7 @@ float4 brdf(Pbr pbr, LightData data) {
     const float F = F_Schlick(data.indirect.NoL, f0_spec, f90);
     specular += surface_reduction * indirect_specular * F;
     remainder -= F;
-    
+
     // Diffuse is Lambertian, which is pre-integrated into the SH diffuse probe
     float3 indirect_diffuse = pbr.albedo.xyz * data.indirect.diffuse * remainder * (1.0 - pbr.metallic);
     diffuse  += indirect_diffuse;