Global illumination at runtime

Hello all:

I’ve run into the following problem, and I haven’t found a satisfactory solution yet. I have the following scenario: A large windowsless room with static lighting with a door to a smaller windowless room with a light that can be switched on/off. Now, the light that can be turned on/off can have its lighting built with lightmass, but when I switch off the light the lightmaps obviously persist and the room is somewhat illuminated when, in theory, there should be only light coming from the light in the large room.

What I want is nice illumination when the smaller room’s light is turned on (dynamic illumination from a movable light leaves much to be desired), but nearly no (or no) illumination when the light is turned off.

I’ve tried things like setting up a PP volume in the small room and setting GI to 0, but then the illumination in the large room is gone as well (and I can see the large room from the small one). Ideally I’d like to change perhaps the lightmaps or something like that using blueprints, but I don’t think that can be done, from what I’ve read.

Any ideas as to how achieve what I want? Is that even possible?


Hello Elaldogs,

Currently there is now way, without using baked lighting as in static or stationary, to have indirect lighting for movable lights. The reason for that is there is no option to calculate for light bounces.

There have been methods, like you mentioned, to use a combination of lights, GI, and PP volumes to achieve this effect. What you could do is have another light in your other rooms, turn off the shadows on this light, and illuminate your other room slightly using that method. This way you can adjust the settings within the light, instead of having the overall affect through PP and GI.

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Thanks for your answer . What I ended up doing was duplicating the actors affected, leaving the movility of one set as static and the other as movable, and controlling their visibility in a blueprint. Hardly an ideal solution, but at least it kind of works.