message: fix incorrect test for occlusion rays
diff: extern RTCDevice uniform ispc_embreeDevice;
  #endif
  -struct Model {
  -
  +struct Model
  +{
  /*! the scene handle we can use to tell embree to trace rays against this scene */
  uniform RTCScene embreeSceneHandle;
  @@ -44,34 +44,36 @@ struct Model {
  //! volumes contained in the model
  uniform Volume *uniform *uniform volumes;
  uniform int32 volumeCount;
  -
  };
  /*! trace a ray (using embree where possible) */
  -inline void traceRay(uniform Model *uniform model,
  - varying Ray &ray)
  +inline void traceRay(uniform Model *uniform model, varying Ray &ray)
  {
  #if USE_EMBREE3
  uniform RTCIntersectContext context;
  rtcInitIntersectContext(&context);
  - rtcIntersectV(model->embreeSceneHandle,&context,(varying RTCRayHit*)&ray);
  + rtcIntersectV(model->embreeSceneHandle,
  + &context,
  + (varying RTCRayHit* uniform)&ray);
  #else
  rtcIntersect(model->embreeSceneHandle,(varying RTCRay&)ray);
  #endif
  }
  /*! determine if ray is occluded (using embree where possible) */
  -inline bool isOccluded(uniform Model *uniform model,
  - varying Ray &ray)
  +inline bool isOccluded(uniform Model *uniform model, varying Ray &ray)
  {
  #if USE_EMBREE3
  uniform RTCIntersectContext context;
  rtcInitIntersectContext(&context);
  - rtcOccludedV(model->embreeSceneHandle,&context,(varying RTCRay*)&ray);
  + rtcOccludedV(model->embreeSceneHandle,
  + &context,
  + (varying RTCRay* uniform)&ray);
  + return ray.t < ray.t0;
  #else
  rtcOccluded(model->embreeSceneHandle,(varying RTCRay&)ray);
  -#endif
  return ray.geomID >= 0;
  +#endif
  }
  /*! Perform post-intersect computations, i.e. fill the members of
  