Fix T65298 Eevee: Principled BSDF doesn't use specular with metals

This does add some more register pressure as it passes a new vec3 down
the shading function. But for now we care more about accuracy than
efficiency.

1 files changed, 2 insertions, 1 deletions

diff --git a/source/blender/draw/engines/eevee/shaders/default_frag.glsl b/source/blender/draw/engines/eevee/shaders/default_frag.glsl
index c568b4d94be..64a1c725a6b 100644
--- a/source/blender/draw/engines/eevee/shaders/default_frag.glsl
+++ b/source/blender/draw/engines/eevee/shaders/default_frag.glsl
@@ -29,8 +29,9 @@ Closure nodetree_exec(void)
   vec3 dielectric = vec3(0.034) * specular * 2.0;
   vec3 albedo = mix(basecol, vec3(0.0), metallic);
   vec3 f0 = mix(dielectric, basecol, metallic);
+  vec3 f90 = mix(vec3(1.0), f0, (1.0 - specular) * metallic);
   vec3 out_diff, out_spec, ssr_spec;
-  eevee_closure_default(N, albedo, f0, 1, roughness, 1.0, out_diff, out_spec, ssr_spec);
+  eevee_closure_default(N, albedo, f0, f90, 1, roughness, 1.0, out_diff, out_spec, ssr_spec);
 
   Closure result = Closure(out_spec + out_diff * albedo,
                            1.0,