If you wish to have part of your map dark while the rest in daylight, for example you are building a dungeon, mine etc, then you are are a bit stuck if that area also has visual access to the outside. These two screen shots illustrate the issue.
In the 1st we are in the mine, looking out. It is day and as a result the ambient lighting is bleeding into the mine. The rock assets are casting shadows, but it is not as dark as you might expect.
In this picture it is now night and the mine is as dark as you might expect one to be, however the view from the exit shows it is night. It is not possible to have a dark mine/cellar etc with a view outside as the ambient light affects the inside of the mine. The tint (sunrise/sunset) also affects the ambient light of all indoor built areas.
I think It would be very difficult to code this out as the game would have to somehow check for every possible gap in a built area.
However we have volumes and at present there are two volumes that affect the overall light in an area. The Sky volume, where you can adjust the time of day, and the post processing one, where you can play with things like saturation.
If your dark zone does not have a view into the outside then you can use the sky volume and just make it night, however as seen above this would also show a night scene if there is any view to the outside.
The suggestion is to add a darkness/lut or some other volume which would affect the ambient light in an area. Players could then place this in their dark area and reduce the ambient lighting to make that area darker, while at the same time still having the ability to have a bright outside view.
you could use a sky volume to make it night in the area only, or you could also maybe tweak with a global sky volume to make shadows more intense or more black.
Sadly, the problem with using the sky volume is that the sky changes to night when you enter the volume. I covered this in the original post >
If your dark zone does not have a view into the outside then you can use the sky volume and just make it night, however as seen above this would also show a night scene if there is any view to the outside.
So while you can use the sky volume if you have no view of the outside. You cannot do so if you have windows, doors etc that has any view of the outside as entering the volume will instantly switch that view to the time of day set by the volume.
The new dark volume would just adjust the ambient light within the volume and not change the time of day.
Sadly I tried this prior to posting the suggestion. Unfortunately the problem with using gain in the post process is that affects all lights, placed as well as ambient.
So if you reduce the gain it gets really dark. There is no light at all as placed lights, candles, spots and the sky whatever are also reduced in brightness.
Now 0.25 gain. The placed lantern, and the daylight sky have all darkened. I guess this is the expected behavior as gain is acting like the gamma setting in other software?
If we could have a lut/darkness volume placed lights and the sky/ambient light outside the volume would be unaffected and only the ambient light inside the volume would be reduced, or indeed increased.
I confess I do not know if this is possible as I have no experiance of the unreal engine other than fiddling with an early version of its map editor.
