-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Ben Axelrod wrote:
> Can normals per primitive and normals per vertex both be used in a > single shape? Not that I am aware of. > > If not, the only way I can imagine having a shape with some smooth > and some sharp edges is if there is one normal per vertex per face. > Just like the diagram in the VRML spec shows, if a vertex has 2 faces > connected to it, it needs 2 normals for a sharp edge, and either 1 or > 2 for a smooth edge. That's right, however, if you do not specify the vertex normals explicitly in the model, the vertex normals are calculated from the *face normals* using the crease angle. If the face normals have an angle smaller than the crease angle, the vertex normals will be an average of the two face normals. For sharp edges you will indeed have to duplicate the vertices to accommodate the different face normals (as explained here: http://www.songho.ca/opengl/gl_vertexarray.html) On the other hand, if you want only sharp edges, you can bind normals per face and save yourself this whole escapade. Honestly, it is simpler to export the vertex normals from whatever tool you are using to produce the data than to fidget with the crease angle - it is only a kludge to let the program guess the model author's intentions. Regards, Jan -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (GNU/Linux) Comment: Using GnuPG with Mandriva - http://enigmail.mozdev.org iD8DBQFJy+5tn11XseNj94gRAvHGAKCZxOcaPU9FnL73O06533yTtpSalwCg6GFc Kz6Y4w31hZgcHRjbDyna/jY= =dKWV -----END PGP SIGNATURE----- _______________________________________________ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
