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 ? -Fred _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
