On one side I have an emmisive material that loses its glow in-game, whether its in-editor, standalone or build. I have no idea to what’s going on… I’ll upload two images here:
This is what it should look like. On the left we see a truck with an instanced dynamic material that has a scalar parameter of Emmision to 0.0. On the right, we have the Lamp which only has a standard emmisive material.
I have a few questions that would help clear things up. When you say your lamp is using a standard emissive material do you mean that you have assigned a material directly to it and are not using a dynamic material instance?
I suspect that something is influencing the light in-game which is why you lose your emissive value when playing. Would you mind sharing your blueprint in a screenshot for the lamp. Especially if it is interacting with the material at all.
Could you also provide a screenshot of the material graph for the lamp material.
Considering emissive values are working for other assets (like the truck) leads me to think that something is going on either in your material or your blueprint rather than this being a bug with the engine.
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There is nothing wrong with your material that I can see for the lantern(searchlight). My guess would be that you are using a dynamic material instance and the parameters are getting changed at runtime. Could you look at the blueprint for the searchlight and make sure you aren’t doing anything to the material at runtime.
The best way to narrow this down would be to get the searchlight static mesh put it into the level and then apply the material (not a material instance) of the Emmission_Yellow_1 material that you took a screenshot of.
If the emissive is glowing on the static mesh with the material applied then that should stay the same when you play in the editor. That would essentially be proof that something is going on in your blueprint.
It looks like the opposite is happening to the truck right? Where it has an emissive value until you play then it goes away. That can be tested in the same way as the spotlight. There is probably something in the blueprint accessing your emissive value and setting it to 0 on begin play. You can test this by using a basic material that doesn’t have parameters.
Basically, we have no reports of dynamic material instances being broken and I haven’t experienced it on my end with testing. I looks and sounds like you are setting those emissive parameters at runtime by accident. I can’t say for sure without being able to look at your blueprint.
You need to create a dynamic material instance either in construct or the event graph using the searchlight material as a base (or whatever material goes along with the asset). You can then access the parameters of the material and set them in Blueprint. Here is a video series tutorial that we provide for this kind of stuff: Intro to Materials: Dynamic Material Instances | 09 | v4.0 Tutorial Series | Unreal Engine - YouTube
