fix sampling direction of fog color from IBL

When sampling the fog color from the IBL we need to take into account
the IBL transform. This broke recently when the for calculation was
moved in user world coordinates.

shaders/src/fog.fs

@@ -45,7 +45,12 @@ vec4 fog(vec4 color, highp vec3 view) {
         // get fog color from envmap
         // TODO: use a lower resolution mip as we get further (problem we don't have mips!)
         float lod = frameUniforms.iblRoughnessOneLevel;
-        fogColor *= textureLod(light_iblSpecular, view, lod).rgb;
+
+        // when sampling the IBL we need to take into account the IBL transform. We know it's a
+        // a rigid transform, so we can take the transpose instead of the inverse, and for the
+        // same reason we can use it directly instead of taking the cof() to transfrom a vector.
+        highp mat3 worldFromUserWorldMatrix = transpose(mat3(frameUniforms.userWorldFromWorldMatrix));
+        fogColor *= textureLod(light_iblSpecular, worldFromUserWorldMatrix * view, lod).rgb;
     }
 #endif