   Point in Vision
  Hello,I been searching in google how to check if a point is currently viewable.I don't find much info really and I really want this to work :DI have a VECTOR3 point and I want check if the camera currently see it, I mean if there is no walls \ objects hiding it, not if its in the frustum.I thought it has something to do with the ZBuffer but I don't find anything about it too :(Thanks.   
  You've basically got two possibilities here:1. Occlusion queriesYou can set up a query, render your object/point (maybe a little tricky with a single vec3) and then wait for the results as to whether it was actually rendered.Not always supported on all GPU's and tends to be quite slow with high latency.2. Ray-tracingGenerate a ray between the world space camera and position (or whichever space suits) and walk the ray for intersections between the camera and the point. With a good heirarchical/early-rejection test it may not be too inefficient, but can be quite compute heavy.Don't bother trying to use the depth buffer as, even if you read it back, it'll almost certainly be too slow.hthJack   