I have already tried changing the ini settings and turning on dBuffer decals and all that. My material for the walls and floor have white as the emissive color. When I detach the color the decal is visible. How can I get the decal to show up over the emissive color because I need both to work together. I have had no help whatsoever with this and it is for a class project. Please help!
Could these links help?
thanks for the response but they deal with the Dbuffer Decal settings which I mentioned. This is something different where decals dont render properly with emissive materials.
Having the same issue.
I have lights which have a strong emissive value, when a decal is applied to the light, the decal is not visible.
If I find a solution, i’ll post it here.
not really what im getting at, I have strong lights, yes, but I can see the decal fine if I unpin the emissive color value I have for the material on my walls
NOTE: If mine is not the same issue, I will delete my posts to avoid steering the topic elsewhere.
Sorry, what I meant by lights was an actual light mesh lol.
So a material with an emissive value, like what you have there, with colour linked to emissive. I don’t mean actual light objects.
So if I put a decal over the mesh that has emissive material, the decal is visible, except for where the emissive material is.
Like this:
http://i.imgur.com/KqVR93w.jpg
With a very simple emissive material (this is the orange light material):
Ah, then yes we have the same problem. With that mesh you have there, do you want the decal completely covering it? or do you want some light to show through? or maybe parts of the decal to cover parts of it? I would say if u want it completely covered then just take off the emissive entirely, if u want some light to show through maybe try a very small value(like very small) in the multiply node so that some of the decal shows over it, yet that could make it grayish. Test it out and post some pics
I’ll have a video up soon showing off what I’m doing. 
Basically it is an alien growth that is dynamically generated throughout the level (kind of like what Natural Selection 2 does).
Right now it’s just in prototyping stages (2 days of work), and will more likely change how it is done later on for performance reasons, but the decals generate where the growth spawns (they are like green blobs with a decal underneath them).
The decal later on will eventually have gaps in the opacity mask to give a veiny like appearance so only bits of the light will show even when the decal is covering the surface of the emissive.
The good thing currently is that the blobs are set up to destroy the lights if they are nearby, and basically turn the emissive off (0), but if blood splatters on the light or some other decal appears on the light, I don’t want emissive to override the decal, like you see in that first image, and in your example.
I also tried placing a poly plane on the mesh just underneath the light with a transparent material, but this does nothing.
I also tried to set the plane to have an opaque material (no opacity) and make it so it was just hidden in game, but obviously that wasn’t going to work…and it didn’t 
I tried mucking around with the blend settings to no avail, tried a bunch of different things within the material itself to no avail.
I am wondering if maybe in the material editor, there is a node that gets a sample of the world around the material and applies that to the material or something. Even if there was a node like this, it would be pretty expensive in performance I would imagine.
Maybe a particle effect would be best for that where it uses the decal and expands outward and to different areas that you control.(that is if the particle effect doesnt get affected by it also lol) With mine Im thinking of bringing my decal into Zbrush and making a model from the alpha.
Not sure if you saw this yet, but this is what I was doing, but obviously when emissive was shining through the goop, it was kinda bad.
Yea can u put a vid of it doing that?
Ok so I thankfully found a workaround. It actually was pretty easy and I was surprised I didn’t think of doing it sooner. Its basically using the decal/picture as an opacity mask. Like you would do with foliage. The only issue I am having with it is that the other side of the box the material is attached to is black or the material is messed up on that face, but I dont need to worry about it since I have thought of a fix for that as well.
Here’s my new material to show what I mean:
I made the picture i had of a paint splatter into an alpha so I could change the color in unreal itself. Also not sure if connecting it to Normal does anything but what the heck. This is just a workaround and I would still like to know why the original process doesn’t work, but I would guess its most likely something not implemented in Unreal yet.
I found a work around, check the answer. Not sure if it can work for u since ur decal needs depth while mine can be flat.
Ah, I tried that with my decal, but it turns a strange bright green colour and seems to be really stretched when it is in the game world. However the decal inside the material viewer and Content browser looks fine.
It pretty much does this, with the tile pattern and all.
I think its because your putting it as a decal instance where as I put the texture on to a cube. The decal instance needs the texture to be set to Deferred Decal but I have mine set to normal and masked. This wouldn’t work for you since you need it to curve based on your geometry which is what a decal is supposed to do.
I was having this same issue in 2019 (version 4.21) and even though it is years later I figured I would post what eventually solved it. I set Decal Blend Mode to AlphaComoposite and that seemed to have the intended effect (covering the emissive color). Hopefully this works for others / will be helpful for someone.