Jim Wilson wrote: > This is not an ac3d file format problem as it does not show up on > converted models. Been thinking of a couple utilities that could be > used to improve ac3d output (I know David is going to suggest blender > :-)).
Just to be clear, I didn't use the ac3d program, just the file format. I do my 3D modelling in perl, remember? :) I suspect that this problem does happen in converted models; the reason you don't see it is that they rarely have a texture seam across a smooth boundary. That won't work here, as all the boundaries are smooth and there is, mathematically, no acceptable mapping of a single texture to a whole sphere. I use a cube face mapping, which works really well except for the texture seam issue. I should explain the problem a little better. What's happening is that there is no place to put a normal vector in the .ac file. The plib loader thus has to generate its own normals by averaging the normals of each polygon attached to a vertex. For vertices that are "inside" an object/texture, this works fine. But ones on the edge can't average in the normal of the polgon(s) that are on the other texture, as those are part of a different object in the .ac file. So what happens is that a vertex on one texture has a normal vector that is *different* from the normal of the same point on a different texture. This makes that polygon edge look sharp when lit. What's especially frustrating is that (1) I'm generating this file automatically, so I could export the normals explicitly if I wanted to, but the file format won't let me; and (2) it's a sphere! Generating normals is a ridiculously trivial operation -- they're just the coordinate of the vertex. I'll look around at the other formats plib supports. All that I require is that it be easy to generate (preferrably ASCII) and support named objects for the animation. The perl scripts that generated the ball are attached. The ball.pl script spits out the .ac file, while balltex.pl generates the texture Postscript in a very similar manner to the gauge stuff I posted earlier. Pass it an argument of north/south/east/west/top/bottom to tell it which texture to generate. Andy -- Andrew J. Ross NextBus Information Systems Senior Software Engineer Emeryville, CA [EMAIL PROTECTED] http://www.nextbus.com "Men go crazy in conflagrations. They only get better one by one." - Sting (misquoted) _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
