I believe I need alpha changes... In fact what I want to do is a kind of terrain editor for 2D textures.
I mean, let's say I paint something with alpha=0.2. Then, I move to another part of the texture, I choose alpha=0.4 and I start to paint. If I understood well, methods like
blend_texture need a "brush" that is in fact the same size as the original texture, so what is does is a blend between the two. Therefore, it is not possible to select a different blend I'm different regions... I would have to change brush alpha, changing then all the changes.
If setpixel lags for something larger than 50x50, then maybe is not good enough... I don't know. Do you have example of good use of setpixel and/or the GPU approach?
Thank you very much!