1 files changed, 18 insertions, 24 deletions

diff --git a/yum_brdf.cginc b/yum_brdf.cginc
index c7424d0..7a4639f 100644
--- a/yum_brdf.cginc
+++ b/yum_brdf.cginc
@@ -7,6 +7,7 @@
 
 #include "filamented.cginc"
 #include "math.cginc"
+#include "pema99.cginc"
 #include "yum_pbr.cginc"
 #include "yum_lighting.cginc"
 
@@ -76,10 +77,6 @@ float computeDielectricF0(float reflectance) {
   return 0.16 * reflectance * reflectance;
 }
 
-float3 computeDiffuseColor(float3 baseColor, float metallic) {
-  return baseColor * (1.0 - metallic);
-}
-
 float computeSpecularAO(float NoV, float visibility, float roughness) {
   // Lagarde and de Rousiers 2014, "Moving Frostbite to PBR"
   return saturate(pow(NoV + visibility, exp2(-16.0 * roughness - 1.0)) - 1.0 + visibility);
@@ -144,6 +141,17 @@ float4 YumBRDF(v2f i, f2f f, const YumLighting light, YumPbr pbr) {
   }
 #endif
 
+  const float dielectric_f0 = computeDielectricF0(_reflectance);
+  const float3 f0 = lerp(dielectric_f0, pbr.albedo, pbr.metallic);
+  float2 dfg_uv = float2(NoV, pbr.roughness_perceptual);
+  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 direct_standard;
   {
     float remainder = 1.0f;
@@ -163,18 +171,10 @@ float4 YumBRDF(v2f i, f2f f, const YumLighting light, YumPbr pbr) {
     remainder -= Fcc;
     remainder = max(0, remainder);
 #endif
-
-    const float dielectric_f0 = computeDielectricF0(_reflectance);
-    const float3 f0 = lerp(dielectric_f0, pbr.albedo, pbr.metallic);
-    const float3 dfg = PrefilteredDFG_LUT(pbr.roughness_perceptual, NoV);
     const float3 E = specularDFG(dfg, f0);
     const float3 energy_compensation = energyCompensation(dfg, f0);
 
-    // Compute proper diffuse color with metallic blending
-    float3 diffuseColor = computeDiffuseColor(pbr.albedo, pbr.metallic);
-
-    // Fd_Burley already includes 1/PI, so multiply by PI to match Unity intensities
-    float3 Fd = diffuseColor * Fd_Burley(pbr.roughness, NoV, NoL_wrapped_d, LoH) * PI;
+    float3 Fd = pbr.albedo.xyz * (1.0f - pbr.metallic) * Fd_Burley(pbr.roughness, NoV, NoL_wrapped_d, LoH) * PI;
     Fd *= light.attenuation * pbr.ao * remainder;
 
     // Multiply by PI to match Unity intensities (same as Filament's implementation)
@@ -187,6 +187,7 @@ float4 YumBRDF(v2f i, f2f f, const YumLighting light, YumPbr pbr) {
 #endif
     direct_standard = color * light.direct;
   }
+  direct_standard = 0;
 
 #if defined(_MATERIAL_TYPE_CLOTH)
   float3 indirect_cloth;
@@ -256,8 +257,6 @@ float4 YumBRDF(v2f i, f2f f, const YumLighting light, YumPbr pbr) {
 #if defined(_BRIGHTNESS_CONTROL)
     cc_env_refl *= _Brightness_Multiplier;
 #endif
-
-    // Clearcoat Fresnel for view angle
     float Fcc = F_Schlick(cc_f0, NoV_cc).x * cc_mask * _Clearcoat_Strength;
     float3 indirect_specular_cc = Fcc * cc_env_refl;
 
@@ -266,19 +265,14 @@ float4 YumBRDF(v2f i, f2f f, const YumLighting light, YumPbr pbr) {
     remainder = saturate(remainder - Fcc);
 #endif
 
-    const float dielectric_f0 = computeDielectricF0(_reflectance);
-    const float3 f0 = lerp(dielectric_f0, pbr.albedo, pbr.metallic);
-    const float3 dfg = PrefilteredDFG_LUT(pbr.roughness_perceptual, NoV);
-    const float3 E = specularDFG(dfg, f0);
-
+    const float3 f0_spec = lerp(dielectric_f0, pbr.albedo.xyz, pbr.metallic);
+    const float3 ibl_specular_reflectance = lerp(dfg.xxx, dfg.yyy, f0_spec);
     float diffuseAO = pbr.ao;
-    float3 diffuseColor = computeDiffuseColor(pbr.albedo, pbr.metallic);
 
-    float3 Fr = E * light.specular * remainder;
+    float3 Fr = ibl_specular_reflectance * light.specular * remainder;
     remainder = saturate(remainder - Fr);
 
-    float3 Fd = diffuseColor * light.diffuse * pbr.ao * remainder;
-
+    float3 Fd = pbr.albedo.xyz * (1.0f - pbr.metallic) * light.diffuse * pbr.ao * remainder;
 
     indirect_standard += Fr + Fd;
   }