I made the exact same guess. It's logical that this happens if polygons are packed without any border betyween them in the textures, and there's nothing else (other than creating a one-pixel border) you can do to prevent this. The problem being that this would require independant sets of texture coordinates for adjacent polygons (to have a delta of one pixel between the texture coordinates of a vertex for different polygons). And I don't see how you can do that (in the present state of b3d) without unwelding every vertex, which is not a very good idea. So better keep going in this way SSwift : cheating a little bit to minimize the artefacts.
If we had more than 2 texture coordinates sets in b3d, we could make "clever" processing to have adjacent polygons use different sets, thus allowing to have independant texture coordinates for each polygon, without duplicating the vertices. This way we would have perfect, sharp borders.
If we had more than 2 texture coordinates sets in b3d, we could make "clever" processing to have adjacent polygons use different sets, thus allowing to have independant texture coordinates for each polygon, without duplicating the vertices. This way we would have perfect, sharp borders.