anchor.diff:  		vec3 throughput;
       if(bsdfPdf > 0.0) { 
         throughput = UE4Eval(incident, macroNormal, texDiffuse, matParams, ray.dir) * abs(dot(macroNormal, ray.dir)) / bsdfPdf;
  -      // throughput = texDiffuse * abs(dot(macroNormal, ray.dir));
       } else {
         throughput = vec3(0.0);
       }
  
positive.code: 
  vec4 sampleEnvImportance(vec3 incident, vec3 origin, vec3 normal, vec3 diffuse, vec2 matParams) {
    vec4 colorPdf = vec4(0);
    vec4 bin = vec4(radianceBins[int(float(ENV_BINS) * rnd())]);
    vec2 dims = vec2(textureSize(envTex, 0));
    float nominal = float(dims.x * dims.y) / float(ENV_BINS);
    colorPdf.a = nominal / ((bin.z - bin.x) * (bin.w - bin.y));
    vec2 uv = vec2(envTheta, 0.0) + vec2((bin.z - bin.x) * rnd() + bin.x, (bin.w - bin.y) * rnd() + bin.y) / vec2(dims);
    float theta = tan((uv.x - envTheta) * INV_PI * 0.5);
    float x = cos(theta);
    float y = sin(M_PI * (uv.y));
    float z = sin(theta);
    vec3 dir = vec3(x, y, z);
    Hit shadow = intersectScene(Ray(origin, dir));
    if (shadow.index == -1.0 || colorPdf.a > EPSILON) {
      colorPdf.rgb = UE4Eval(incident, normal, diffuse, matParams, dir) * abs(dot(normal, dir)) / colorPdf.a;
      colorPdf.rgb *= envColor(uv);
    }
    return colorPdf;
  }
  
negative.code:     vec3 lightDir;
      ray.origin = origin + baryNormal * EPSILON * 2.0;
  
      // TODO: make this configurable in the materials
      //color += accumulatedReflectance * texEmmissive * 10.0;
  
      #ifdef USE_EXPLICIT
      vec3 direct = getDirectEmission(ray.origin, macroNormal, lightDir);
  