how detect the visibility of many objects

[issaksdu44]

hello

i have many objects with known centre of mass coordinates distributed on a plane.
the objects have 2 main shapes (cudic and cylindrical).

i previously calculated the distance between there centres of mass to detect if they intersect 2 by 2.

now all what i need is to know which object is visible to the others so i can calculate the view factor
related to each object with respect to only the visible onces.

I'm waiting your help. thank's