I have been working on a space simulation, and I want to have ships which may have little boxes around them if they are selected, and I still need to know the screen coordinates otherwise. I have done everything according to spec in the OpenGL SuperBible, and just about every other refrence I can find. Since I dont want my feedback buffer to explode, what I do is I establish what the bounding box for the model is, and I render the front, back, top and bottom of that to the feedback buffer as a quadstrip. This is after using octree culling and so forth to cut down on the set of visible objects. I get really odd results from the feedback. I always get the X coordinate = 3 in any instance where the object is visible on screen, regardless of its location. The only difference I can see between my code and the available tutorials is that my code is doing feedback on a perspective view, rather than an orthoganal view. Has anybody else had a similar problem with the feedback buffers?
I fixed it- actually removed all feedback code and used gluProject() to get the information I needed.