More fine tuning calibration of roughness, and various visual fixes for PBR

jme3-core/src/main/java/com/jme3/environment/util/EnvMapUtils.java

@@ -428,12 +428,12 @@ public class EnvMapUtils {
     }*/
 
     public static int getSampleFromMip(int mipLevel, int miptot) {        
-        return Math.min(1 << (miptot + mipLevel * 2), 8192);
+        return mipLevel==0?1:Math.min(1 << (miptot - 1 + (mipLevel) * 2 ), 8192);
     }
 
     public static float getRoughnessFromMip(int miplevel, int miptot) {
-        float mipScale = 1.2f;
-        float mipOffset = 0.0f;
+        float mipScale = 1.0f;
+        float mipOffset = -0.3f;        
 
         return pow(2, (float) (miplevel - (miptot - 1) + mipOffset) / mipScale);
     }

jme3-core/src/main/resources/Common/MatDefs/Light/PBRLighting.frag

@@ -1,5 +1,5 @@
 #import "Common/ShaderLib/Parallax.glsllib"
-#import "ShaderLib/PBR.glsllib"
+#import "Common/ShaderLib/PBR.glsllib"
 #import "Common/ShaderLib/Lighting.glsllib"
 
 varying vec2 texCoord;

jme3-core/src/main/resources/Common/ShaderLib/PBR.glsllib

@@ -106,6 +106,7 @@ void PBR_ComputeDirectLight(vec3 normal, vec3 lightDir, vec3 viewDir,
     outSpecular = vec3(specular) * lightColor;
 }
 
+//https://knarkowicz.wordpress.com/2014/12/27/analytical-dfg-term-for-ibl/
 vec3 EnvDFGPolynomial( vec3 specularColor, float roughness, float ndotv ){
     float x = 1.0 - roughness;
     float y = ndotv;
@@ -128,7 +129,7 @@ vec3 EnvDFGPolynomial( vec3 specularColor, float roughness, float ndotv ){
     float delta = clamp(( d0 + d1 * x + d2 * y + d3 * x * x + d4 * x * y + d5 * y * y + d6 * x * x * x ), 0.0, 1.0);
     float scale = delta - bias;
  
-    bias *= clamp( 50.0 * specularColor.y, 0.0, 1.0 );
+    bias *= clamp( 2.5 / (roughness) * specularColor.y, 0.0, 1.0 );
     return specularColor * scale + bias;
 }
 
@@ -142,8 +143,8 @@ vec3 ApproximateSpecularIBL(samplerCube envMap,sampler2D integrateBRDF, vec3 Spe
 
 vec3 ApproximateSpecularIBLPolynomial(samplerCube envMap, vec3 SpecularColor , float Roughness, float ndotv, vec3 refVec){
     //TODO magic values should be replaced by defines.
-    float Lod = log2(Roughness) * 1.5 + 6.0 - 1.0;
-    vec3 PrefilteredColor =  textureCubeLod(envMap, refVec.xyz,Lod).rgb;    
+    float Lod = log2(Roughness) * 1.1 + 6.0 - 1.0;
+    vec3 PrefilteredColor =  textureCubeLod(envMap, refVec.xyz, Lod).rgb;    
     return PrefilteredColor * EnvDFGPolynomial(SpecularColor, Roughness, ndotv);
 }