Do possible to change colors of entity (materials) in real time.
Like my.red += 1 * time_step; The same with ambient, diffuse and specular,
F.e. to make a slider which one changes entity color.
Then with three sliders we'll be able to make all colors, like painting a car (basicly white) by player in the game (f.e. in paint-shop or something).
Maybe it's possible by .fx files or something, but that way will be more easy.