One Light Fades Another

Unity Engine
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1

I’m noticing that if I place a point light somewhere within the interior of my building model, and then place another one somewhere else in the building, the second light can affect the appearance of the first. None of the settings on the first light change, but it’s brightness/intensity kind of fades. This effect continues on already added lights, every time I add another one.

I don’t have a lot of knowledge about this, so it could be that there’s a very good reason why this happens.

Does anyone know what it is?

2

you can not impact that.

The lights are vertex lights and all vertices within a lights range are affected by the light.

if multiple lights are affecting a vertice, their impacts will sum up.

There is no possibility to alter this behavior technically (so not a unity thing) other than making your lights small enough to never overlap.

3

I get it. I figured at the points where the two lights intersect, the light would kind of “blend” together. Instead one actually kind of overrides the other.

Anyway - working on it.

Here’s what I’m talking about anyway just to clear it up. Watch the bottom-left and bottom-right rooms as I move the top-right light around.

http://www.nocturnalware.biz/temp/example.mov

4

They do blend, if you haven’t exceeded the number of lights that can affect a single object. For vertex lights this is 8. For pixel lights, it depends on what you have in the quality settings. Note that pixel lights aren’t going to work on the device anyway, so set everything to force vertex. If you have too many lights affecting an object, then you have to break it up into smaller parts.

Of course, dynamic lights aren’t the fastest anyway; if they’re not going to move, then it would be better to use lightmaps instead. Then you have no limitations on lighting. Having multiple dynamic lights all active on an iPhone isn’t going to be great for the framerate.

–Eric

5

Thanks. I’m pretty new to all this but it sounds like lightmapping is going to be my next area of research!