How do I fade the entire screen? Not just a couple polys. I know that I can find which polys are on the screen and fade them through blending at the same time but is there a better way to do it?
quick thought answer :
-play with gamma if possible
-use a big quad on the screen and make it more and more opaque with the desired bmp/color.
-decrease your lights intensity
If blending from one scene to another, not just from the scene to a single colour, is what you want, then the accumulation buffer would be perfect for that.
Unfortunately, it’s not hardware accelerated (though it may be on some pro boards).
Then you can try copying the two scenes you want to blend to textures which are large enough and blend two quads (filling the entire screen) textured with those textures.