I have a texture which is only grayscale. I want to render this texture on a quad in front of my scene. But I want to see through the white parts of the texture and not through the black parts. Can this be done by blending functions or do I need an alpha channel?
Ok, I inverted my texture. Now I can see through the black parts and have only the white parts on the screen. To switch this white parts to black I use the following blend function: