PBRLighting now use the world normal to fetch irradiance instead of the reflection vector.

Also added some comment for the parallax fix to explain what it does and where it comes from

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

@@ -202,7 +202,8 @@ void main(){
     }
 
     vec3 rv = reflect(-viewDir.xyz, normal.xyz);
-    //prallax fix for spherical bounds.
+    //prallax fix for spherical bounds from https://seblagarde.wordpress.com/2012/09/29/image-based-lighting-approaches-and-parallax-corrected-cubemap/
+    // g_LightProbeData.w is 1/probe radius, g_LightProbeData.xyz is the position of the lightProbe.
     rv = g_LightProbeData.w * (wPosition - g_LightProbeData.xyz) +rv;
 
      //horizon fade from http://marmosetco.tumblr.com/post/81245981087
@@ -213,7 +214,7 @@ void main(){
 
     vec3 indirectDiffuse = vec3(0.0);
     vec3 indirectSpecular = vec3(0.0);    
-    indirectDiffuse = textureCube(g_IrradianceMap, rv.xyz).rgb * diffuseColor.rgb;
+    indirectDiffuse = textureCube(g_IrradianceMap, wNormal.xyz).rgb * diffuseColor.rgb;
 
     indirectSpecular = ApproximateSpecularIBLPolynomial(g_PrefEnvMap, specularColor.rgb, Roughness, ndotv, rv.xyz);
     indirectSpecular *= vec3(horiz);