I want to composite 2 images and display it on a plane. I want to have 75% of the first image and 25% of the second.
I am able to display the first image and the second separatly but I am not able to blend both with a factor that I control.
How can I do it?
There is a handy extension: envcombine. Check it out.
If you got an Nvidia card, try regcoms, they’re very useful.
Hows about very simple vertex alpha? Something like render the first image at 100% opacity and then the second at 25% opacity. The result would be 75% the first and 25% the second. Unless I’m missing something here…
My error was very stupid 
I use 0-1 not 0-255 value range when setting the alpha in the texture.