Daylight in game (DOOM 3)

Where to download the patch that makes daylight in the game.
Console commands, such as R_GAMMA - makes dark places light, and light ones just white ...
It is necessary that the dark places become light and the light ones remain so, that is, everything becomes normal with daylight, and then it is dark like in a black man's, why at all did that? what interest is wandering in the dark?