BTW recently it turned out that there are a few machines that will MAV when you try to do drawing operations directly on a texturebuffer (as seen with the Oval command). THerefor I'd suggest to draw to the backbuffer and then copyrect to the texturebuffer, and never ever draw to the texturebuffer directly.
BTW to set the transparency of a texture you will have to set the alpha channel manually, even if you used to copy black pixels to a masked texture. The transparency of black texels is only set autmaticly if you load a texture with the flag 4, contrary to a created texture.
This may be useful for you:
http://www.blitzbasic.com/codearcs/codearcs.php?code=1806
BTW to set the transparency of a texture you will have to set the alpha channel manually, even if you used to copy black pixels to a masked texture. The transparency of black texels is only set autmaticly if you load a texture with the flag 4, contrary to a created texture.
This may be useful for you:
http://www.blitzbasic.com/codearcs/codearcs.php?code=1806