Curtis L. Olson writes: > Jim Wilson writes: > > Yes it sure is strange. When David moved it to the main scene graph that > > fixed the problem, and just about eliminated the z-fighting between model > > objects. When I get a chance I'm going to take a look at > > sgCullandDraw() and the ssg source, just out of curiosity. > > There's nothing magic about ssgCullAndDraw() ... it just traverses the > scene graph and dumps out the corresponding opengl draw commands: > > do_needed_changes();
Make that do_needed_*STATE*_changes() > glBegin(); > do_opengl_draw_commands(); > glEnd(); > > repeat for each leaf node. > > There is really no performance hit with using multiple ssgRoots. > > The only thing slightly tricky is that each leaf node in the scene > graph can have an ssgSimpleState attached and ssg does 'lazy' state > changes. In otherwords, ssg keeps track of the current opengl states > and when a new ssgSimpleState is applied, it only changes the items > that are different from the previous state. OpenGL state change can > get expensive, so minimizing it can be a big performance win. > > As long as you understand what's going on inside of ssg (which is > pretty straightforward) it is not difficult to mix ssg drawing with > your own raw opengl drawing. The biggest thing to watch out for is > 'state' management. If you change state outside of ssg's state > changing mechanism, then you can throw ssg out of sync so it might not > set a state it needs to and you can get your ssg rendered stuff > screwed up. > > Regards, > > Curt. > -- > Curtis Olson IVLab / HumanFIRST Program FlightGear Project > Twin Cities [EMAIL PROTECTED] [EMAIL PROTECTED] > Minnesota http://www.menet.umn.edu/~curt http://www.flightgear.org > > _______________________________________________ > Flightgear-devel mailing list > [EMAIL PROTECTED] > http://mail.flightgear.org/mailman/listinfo/flightgear-devel -- Curtis Olson IVLab / HumanFIRST Program FlightGear Project Twin Cities [EMAIL PROTECTED] [EMAIL PROTECTED] Minnesota http://www.menet.umn.edu/~curt http://www.flightgear.org _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
