Fixe bug in pbr

native/source/Algorithm/MicrofacetGGX.c

@@ -35,6 +35,17 @@ float ggx_g_smith(float n_dot_v, float n_dot_l, float roughness)
     return ggx_g1(n_dot_v, roughness) * ggx_g1(n_dot_l, roughness);
 }
 
+float ggx_visibility(float n_dot_v, float n_dot_l, float roughness)
+{
+    float alpha = roughness * roughness;
+    float alpha2 = alpha * alpha;
+
+    float ggx_v = n_dot_l * sqrtf(alpha2 + (1.0f - alpha2) * n_dot_v * n_dot_v);
+    float ggx_l = n_dot_v * sqrtf(alpha2 + (1.0f - alpha2) * n_dot_l * n_dot_l);
+
+    return 0.5f / fmaxf(ggx_v + ggx_l, FLT_EPSILON);
+}
+
 vec3s ggx_sample_vndf(vec3s n, vec3s v, float roughness, float u1, float u2)
 {
     // Build local frame around n.