All graphics APIs are the same: the texture V coordinate is an index into the image array. Thus, when V is 0, the first scanline passed to the API is addressed; when V is 1, the last scanline is addressed. Sometimes, art gets a little confused, because common loaders for JPG and PNG bitmaps return the data as the top scanline first, and the BMP/TGA formats are specified as the bottom scanline first (unless special bits are set in the TGA). In addition, the DDS texture format is specified as the bottom scanline first.
Now, what does this have to do with the price of bread in China? Well, I don't get the behavior I expect in some meshes. V should go from the bottom to the top, but it goes from the top to the bottom, even on images that are defined as bottom-scanline-first.
Is this a bug (i e, jME "should" work like the general graphics APIs), or is this a "feature"? Note: DXT compressed DDS images don't get flipped by the texture loader, even if you ask for it, so some art just can't work the way that jME works right now. I'd prefer to define that V=0 means first scanline, and leave it at that. Opinions, suggestions, etc?