I have a map and I’m trying to put some data on top of it, I’m building a texture and in those points where there is no data I make alpha = 0. I also need to control the data transparency. So I do a quad after drawing my background and I place my texture on it, but I’m getting the color of the quad thru the “holes” in the data, while the holes should be completely transparent.
How can I do it completely transparent on the “holes” and transparent on the data?..

This is not the discussion for this - use Codeing: beginners instead
The short answer to your question is alpha testing. See ALPHA_TEST state and AlphaFunc function.