It occurred to me that our 3-D modelers might not all be running plib cvs. Andy came up with an excellent improvement to the ac3d loader/optimizer (new optimizer actually) that incorporates logic to automatically split vertices in two so that they go into seperate normal calculations (averages). Briefly, the plib change gives us sharp edges automatically.
For the many aircraft models this change really helps. But for the models what were already designed to work around the problems with the earlier plib, they end up looking a little worse. I've gone through a few and for the most part they have square or sharp leading edges on the wings now. I'm bringing this up now because this is the version of plib that the next release of FlightGear will released for. Looking at my own models, this has proven to be a very difficult problem to deal with. Basically what you'll see is that a sharp edge is created whenever the angle between the normals of adjacent surfaces is greater than 46 degrees. Another way to describe the way this works is that a cylinder object will appear round if it has 8 or more sides. 7 sides will have sharp edges. This creates a serious problem for ac3d/blender modelers because you will need at least 4 surfaces to make up a leading edge. In practice you actually need 6 or more because wing edges are not perfectly round. At some point simgear and plib will have to be modified to support the ac3d 4 format or some similar scheme for setting the angle. Either that or we'll finally be able to move to a file format that actually supports normals "normally". For the time being though, I propose that we try to get this default angle to a higher value. From my testing 61 degrees seems to be a good number. 61 degrees means that a 6 sided cylinder will be smoothed. Anything less (e.g. 4 or 5 sides) will be sharp sided. Many of the aircraft models will still need some modifications to recover their rounded shapes at 61 degrees, but the process is much easier, with far fewer vertices, etc. Best, Jim _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
