1 files changed, 8 insertions, 0 deletions
diff --git a/brdf.cginc b/brdf.cginc
index a12c256..8714181 100644
--- a/brdf.cginc
+++ b/brdf.cginc
@@ -12,6 +12,10 @@ float pow5(float x) {
   return x2 * x2 * x;
 }
 
+float Fd_Lambertian(float NoL) {
+  return NoL;
+}
+
 // Schlick "An Inexpensive BRDF Model for Physically-based Rendering".
 // Equation 24.
 // f0: Reflectance at normal incidence. Typically around 0.04.
@@ -209,7 +213,11 @@ float4 brdf(Pbr pbr, LightData data) {
     direct_specular = max(0, direct_specular);
     specular += direct_specular;
 
+#if defined(F_OREN_NAYAR)
     float Fd = Fd_OrenNayar(pbr.roughness, data.common.NoV, data.direct.NoL, data.direct.LoV);
+#else
+    float Fd = Fd_Lambertian(data.direct.NoL);
+#endif
     float3 direct_diffuse = Fd * (1.0f - pbr.metallic) * pbr.albedo.xyz * data.direct.color;
     direct_diffuse *= layer_attenuation;
     direct_diffuse = max(0, direct_diffuse);