What you are seeing in the screenshot is just the reflection of the emissive materials. You can use emissive materials to light the environment only with static lighting, and for that you need to enable Use Emissive for Static Lighting in the object’s details panel.
That’s about it then i guess, considering the size of the meshes. Emissive lighting is quite weak and it doesnt generate bounced light so dont expect much from it really. What you can do however, create a tube light in front of that mesh and set that light’s Min. Roughness Value to 1. Now the light source will light the environment while the emissive takes care of reflections.
I have created light fixtures which light the room using emissive textures. However, it seems these lights have a very steep attenuation. I could not find a setting to adjust this value. How it possible to use these emissive lights to light my whole room? As as aside, is there much performance difference between using emissive materials vs point lights for this purpose?
I also have some other questions which I would be grateful if anyone could advise me.
Hi Jack. I have that setting enabled and the emissives are definitely lighting my map, just their effect is very short ranged. Increasing the intensity barely increases this.
Well it will increase the amount of light emitted but again, dont expect anything as good as a normal light source. Emissive also doesnt generate volume lighting samples, as far as i know so you’ll have problems with lighting skeletal and movable meshes if you want to go fully-emissive lighting.
Emissive would be the worst for that kind of setup really. Movable light sources would be the best, but if you want to use static lighting then use Stationary tube lights. You can change the intensity of stationary lights in run time so you can set the intensity to 0 whenever the wall is destroyed. Limitations are, you cannot have more than 4 stationary lights’ attenuation radius overlapping and bounced lighting(GI) still stays even though you set the light’s intensity to 0 to turn it off in game. So i would consider movable light sources if performance is managable.
Thats a shame. Are you implying the size of the meshes could be reworked to get a better effect? Failing that I will implement the tube light!
Interesting. I believe you are right, I just tested and the emissive light did not light my character.
The reason I decided to try fully-emissive lighting was that my walls eventually should be destructible, and having light in the texture I thought would allow for simpler destruction mechanics, simply destroy the mesh and the light also vanishes. I will find a way to work around that, it should not be too difficult to remove lights when the asset is destroyed.
Thanks for all your advice Jacky, its been very helpful. I think I have to go for movable light sources really if the environment will be destructible, else things might end up looking pretty bad once a few objects get destroyed. Do you know anywhere where I can look up more about performance guidelines? This is all new to me! How many dynamic lights can you get away with in certain situations etc…before performance takes a hit
Edit: For anyone else who reads this, I found it at Performance Guidelines for Artists and Designers | Unreal Engine Documentation
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Movable lights get more expensive if more than one light affect the same object but they are very cheap if they dont cast shadows.