We now have an extensive docs about occlusion query in Castle Game Engine.
We also fixed occlusion query for shapes with blending, and made it behave correctly when batching is used (right now, batching has to be disabled for the scenes that use occlusion query).
On a more general note: Sorry for the relative silence in the news in last 2 weeks. We’re busy making a few things at once, big (memory optimizations, Delphi compatibility, docking editor) and small (Android x86, editor gizmos improvements). I will gradually post about them 🙂