Revert "Use f0 in fresnel schlick"

This reverts commit acdafc5566.

data/shaders/utils/getSpecular.frag

@@ -3,10 +3,9 @@
 vec3 getSpecular(vec3 normal, vec3 eyedir, vec3 lightdir, vec3 color, float roughness)
 {
     // Half Light View direction
-    vec3 f0 = vec3(0.040);
     vec3 H = normalize(eyedir + lightdir);
     float NdotH = max(0., dot(normal, H));
     float normalisationFactor = (roughness + 2.) / 8.;
-    vec3 FresnelSchlick = f0 + (1.0f - f0) * pow(1.0f - max(0., (dot(eyedir, H))), 5);
+    vec3 FresnelSchlick = color + (1.0f - color) * pow(1.0f - max(0., (dot(eyedir, H))), 5);
     return max(pow(NdotH, roughness) * FresnelSchlick * normalisationFactor, vec3(0.));
 }