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Lighting Help!

Still a noob and learning, please can someone help me?

I have created a 'massive warehouse' as a showroom. I want to setup sequence so when trigger is activated, the lights to the warehouse come on, one by one. I have set this up in sequencer, using visibility as my keyframes to turn each light on individually in order, one by one.

Here are the issues I am running into: - If i make the lights static, lighting is baked and the room is bright no matter what - If i make them stationary, then it tells me I can only use like 3 lights, all other have big red crosses through them. The scene is going to have like 12/15 lights from the ceiling. Also, once built, the room is still lit. When the lights turn on the room is definitely brighter, but it should be pitch dark. - If I use movable lights, all works well but worried about performance.

Ultimately this is a project for VR so I know performance cost is intensive with movable lights. This is all before I've added a shiny car inside the environment which is going to be high detailed with badass paint material for reflections etc. (using unreal automotive pack).

How should I go about doing this? Having a room, which is pitch black, become brighter through the use of 12/15 'floodlights' which will turn on one by one.

Product Version: UE 4.12
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asked May 17 '17 at 07:54 PM in Using UE4

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avatar image nebula42 May 17 '17 at 08:38 PM

Can someone help me on this now? Frustration is creeping in! Below is my level BP where 2 sequence events occur. First is doors slide open. Second is set of lights turn on using visibility (with sound effect when each light is on). When I press play in the sequencer, all looks good.

HOWEVER, if I go to hit play in the viewport etc, I can hear the sounds for each light turning on, but the actual light doesn't turn on! Any ideas?

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2 answers: sort voted first

First of all, if you're getting crosses on the lights then it means they are casting shadows. If you don't already know there's a pretty low limit to how many shadow casting lights can affect a single object, and having 15 of them would destroy performance so make sure cast shadows is disabled.

Regarding stationary and static lights, the performance impact of a stationary light over a static light is pretty small, what is more of an impact is having a movable light which I don't know the actual performance statistics on, so I can't say by how much. Either way, what you want is a stationary light. It will allow you to adjust the light during runtime which is what you're trying to achieve.

As for the light baking into the scene, there is no 'don't bake this into the lightmap' option as far as I can tell for lights, so the only thing I think you could do is set each light to have their intensity as 0, bake the lighting and then the lightmap should be dark and no longer have the lights bake into it. Why you would really need baked lighting unless you have windows or something affecting the interior ambient lighting I don't know. You can then use your method to enable the lights but this time rather than using visibility, you'll need to increase the intensity back to whatever you want it to be. You could also make this gradual, so it's a smooth transition on rather than a instant flash.

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answered May 17 '17 at 08:52 PM

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Geosmith Tech.
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avatar image nebula42 May 17 '17 at 09:45 PM

@2Awesome4You Thanks so much man, really appreciated. This makes perfect sense. I Set it up using stationary lights and intensity again, worked perfectly. Currently I only tested the environment with 3 lights, but will add more and be sure to turn off 'cast shadows' on any that I don't actually need.

Massive help for a beginner like me, once again, truly appreciated! I'm sure I'll have ALOT of questions to come!

avatar image Geosmith Tech. May 17 '17 at 09:47 PM

No worries! I'm happy to help. If you want slightly more info on performance, check out the guidelines for level designers here: https://docs.unrealengine.com/latest/INT/Engine/Performance/Guidelines/

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One static object can receive lightning only from 4 stationary lights. So, if you make more than 4 lights to not overlap for single mesh, it can do the job.

Anyway, I think 15 switchable lights is a lot for vr, maybe you need to simplify this scene.

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answered May 17 '17 at 08:25 PM

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avatar image nebula42 May 17 '17 at 08:29 PM

Thanks for your help man. Do you know have any way of creating stationary light where the scene is still completely dark until light is visible? Currently I can only do this with movable lights.

avatar image Geosmith Tech. May 17 '17 at 08:57 PM

Again regarding this, stationary lights have no limit to how many can affect the object, what matters is whether they cast shadows or not. Testing it on a 980 ti, over 100 stationary lights have little to no performance impact from a small distance, and when the camera is right in the center of these lights my FPS doesn't drop below 80.

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