> This is an optimization to avoid running really expensive shaders on > geometry that will be hidden from view. The GPU has an "early Z" > capability and won't run a fragment shader if it knows the result will > be discarded.
But that can't be all that is going on. In this case I'd expect that if I leave the pass out, the system would slow down. However, what actually happens when I remove the first pass is that the system runs just a bit faster, but I get z-ordering problems for distant objects which sometimes appear in front. Do we actually draw all the scenery in one go, or on a per-tile basis? Do we really not run the terrain fragment shader when the terrain is seen through the cockpit floor (my system seems to slow down even though no terrain is seen in the event and the framerate responds to my shader quality settings)? Much to my annoyance, coordinate systems for instance are discontinuous across tile boundaries, which leads for instance to artefacts when using 3d noise to create variations in the fog density, but I don't know if coordinate discontinuities have anything to do with what we draw. Somehow, this connects to the render bins, right? Thanks, for any help, I'd really like to understand this better (I am reading up the theory as we talk...), so I promise to (mostly) ask Flightgear specific things. * Thorsten ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
