Fix reflection mip level constant on PBR textured scene.

src/6.pbr/2.2.2.ibl_specular_textured/2.2.2.pbr.fs

@@ -157,7 +157,7 @@ void main()
     vec3 diffuse      = irradiance * albedo;
     
     // sample both the pre-filter map and the BRDF lut and combine them together as per the Split-Sum approximation to get the IBL specular part.
-    const float MAX_REFLECTION_LOD = 4.0;
+    const float MAX_REFLECTION_LOD = 5.0;
     vec3 prefilteredColor = textureLod(prefilterMap, R,  roughness * MAX_REFLECTION_LOD).rgb;    
     vec2 brdf  = texture(brdfLUT, vec2(max(dot(N, V), 0.0), roughness)).rg;
     vec3 specular = prefilteredColor * (F * brdf.x + brdf.y);