Is there any limit, regarding number of objects casting/receiving shadows at same time, or limit related to poly count of caster receiver? For example is it better to have whole level(static geometry never chenged during gameplay) as a one big chunk or as a bunch of small objects? Occlusion wise, is it done automatically or there are some commands for it? If level is one big chunk, parts not bisible are occluded better than if level is bunch of small objects?