   occlusion culling
  I'd like some advices about possible culling solution to this matter:suppose you are in a 3d aircraft cockpit and you want to cull terrain parts which are occluded by the cockpit itself. Possible solutions ?With a 2d cockpit is rather simple, could use also scissor testing, but how can i deal with a 3d cockpit ?Thanks for any suggestion ...   
  define a simple shape that corresponds loosely to the shape of the cockpit glass. Basically, find a set of vertices that, when connected by lines,enclose the entire cockpit glass. The simpler the shape, the better.Knowing these points relative to your eye point, you can create a series of planes defined by your eye and any 2 adjacent points on this window-shape. These planes then become a viewing frustum against which you can do occlusion tests. Since plane tests with most bounding volumes are quite cheap, this sort of method isnt a problem provided you arent testing every single triangle.assuming you dont have trouble constructing the planes, the only real hurdle you might encounter is keeping things in the correct coordinate system (local to your plane, your pilot,or the world).gl   