Frederic Bouvier said: > Curtis L. Olson wrote: > > > Frederic Bouvier wrote: > > > > >I am leaning to a 4 level quality choice : > > > > > > 0 - actual state : clouds are making holes in mountains when seen from > > >below, > > > translucent surfaces are making hole in clouds underneath. > > > > > > 1 - clouds are blended with mountains > > > > > > 2 - translucent aircraft surfaces are blended with clouds but with > > > problem with underlying 3d static objects ( clouds between the > > >propeller > > > disc and 3d objects are not seen ) > > > > > > 3 - total correctness > > > > > >Perhaps 2 and 3 can be collapsed with no extra cost. There is already a > > >property to enable or disable the extra work. I will add quality on > > >rendering soon. > > > > > > > > > > Fred, > > > > At one point, clouds were drawn "back to front" with respect to > > altitude. This should avoid transparancy issues, except for things like > > trees, prop disks, and canopies that may get drawn earlier. Perhaps > > subsequent work on clouds caused this drawing order to be lost, but if > > we draw the clouds back to front based on altitude, it should reduce > > most or all of the issues you are working on without needing any sort of > > extra multi-pass effort. > > This simple scheme ( "back to front" ) works well with flat ground. It > begins to be tougher when things are going to interleave themselves. > What is back to front when you have a plane between cloud layers and the > viewer in that plane, a cloud layer in a valley, several static > objects with translucent faces ( like the bridges or any metallic > structure ) ? > > If we draw all clouds before the terrain and objects, depending > on the fact that we enable depth test or not, we will have clipped > mountains or no clouds blended with them. > > If we draw all clouds after the terrain and objects, we must use depth > test and then we have holes for canopy, trees or bridges ( without > alpha test, with it it's better but not perfect for half transparencies ) > > At the moment, I think we have the best overall result without extra > pass : we draw clouds above the viewer before the scene and clouds > below after. With extra passes, we can clear issues in their order > of annoyance, and it would be configurable to cope with the variety > of setup encountered in our user base. > > The main programming effort is done. I want to review the screenshot > rendering before releasing a patch. > BTW: do we respect a freeze period in case some annoying problem > show up and need a 0.9.4a release ? >
We first ran into this problem with the old back to front scheme when David did the first trees. But I'm wondering now why the prop disks are a problem. Shouldn't the aircraft model be on the bottom of the stack anyway? Generally there's nothing between it and the camera. Best, Jim _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
