i recently download the nehe''s opengl tutorials and found that the graphics in lesson17 ( which print text using texture ) is not quite right. The text didn''t become transparent and i can still see the black background. When i change the blending function to GL_ONE_MINUS_SRC_ALPHA, it work right ! Is it a hardware / software problem ? My display card is nVidia Riva 128zx

What you''re seeing is correct, that''s the nature of blending. If you want true transparency, you have to use masking with two or more images or use alpha channels like Targa .TGA files offer.

Jason