i guess i have to throw LP away and perform raytracing with sky on CPU (just rays - top/left/right/forward/backward) for every object that is moving , to learn if object is under indirect lighting or not..
just occlusion factor = 5results/5 = 0...1
My appologize for going OT here - but this one needs a comment
Note that this will be quite slow unless you have some kind of hierarchy in which you store your scene (and you're back to beginning - it can be Octree, KDtree, BVH, BIH, etc. - you will still have to build it (or pre-compute it for static scenes). Also note that you will get your results per object, which looks acceptable only for small objects.
E.g., you might be able to test 5 rays for some higher number of complex objects in scene without hierarchy but it will look bad (you could accumulate occlusion over time - but moving objects would blink) - e.g. you will need more rays (more samples), and so your performance will drop (a lot) - which implies the need of hierarchy for scene (this can accelerate the ray tracing process).
Hint. You could use short rays for computing occlusion (even though it won't be global then), with good hierarchy (read SAH KD-tree, Split-BVH, etc.) this gives you ability to compute tens of milions or even hundreds of milions rays per second on todays hardware.